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LC77
User Manual
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Sencore LC77 User Manual

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LC77
“AUTO-Z”
CAPACITOR — INDUCTOR
ANALYZER
Operation, Application, and Maintenance Manual
SENCORE
3200 Sencore Drive, Sioux Fails, South Dakota 57107
1
Notes
Introduction
DESCR I PTION
Capacitor and inductor usage is extensive, encompas sing all facets of industrial and consumer electronics. Very few circuits lack either of these components. Be cause the transistor gave way to the IC, and the IC gave way to the LSIC, capacitor and inductor usage continues to increase rapidly since neither of these com
ponents can be physically incorporated into ICs on a broad basis.. Though they have changed some in phys ical size, capacitors still perform the same basic func tions. But in today's circuits, more than ever before, the tolerances and parameters of capacitors and induc tors are critical to proper circuit operation.
Capacitor value and tight tolerance is just one impor tant parameter. In today’s high performance circuits, leakage, dielectric absorption, and ESR are necessary indicators of a capacitor’s ability to perform properly in circuit. Inductors too, require tight tolerances and quality checks. Unless all of these parameters can be thoroughly analyzed, troubleshooting becomes a gues sing game.
The Sencore LC77 “AUTO-Z” takes the guess work out of capacitor and inductor testing. It provides automatic tests of capacitor value, leakage, ESR, and a patented dielectric absorption test. Inductors are automatically analyzed for value and quality with patented tests. The LC77 is a complete, automatic, microprocessor-control- led capacitor and inductor analyzer. Its features make it ideally suited for both single component analyzing in service or maintenance work, or for large volume
batch testing in a lab or incoming inspection.
Features
The Sencore LC77 “AUTO-Z” is a dynamic, portable, automatic capacitor and inductor tester. It is designed to quickly identify defective components by simply con necting the capacitor or inductor to the test leads and pushing a test button. The test result is readily dis played on an LCD readout in common terms. All capacitor and inductor test results may also be dis played as good/bad compared to standards adopted by the Electronic Industries Association (ElA). User de fined limits may also be programmed into the LC77 for the good/bad comparison.
In addition to testing capacitors for value up to 20 Farads, the LC77 checks capacitors for leakage at their
rated working voltage, up to 1000 volts. ESR is checked with a patent-pending test, and an automatic, patented test checks capacitor dielectric absorption. A patented inductance value test provides a fast, accurate test of true inductance. A patented ringing test checks coils, deflection yoke, switching power supply transformers, and other non-iron core inductors with a fast, reliable good/bad quality test.
Automatic lead zeroing balances out test lead capaci tance, resistance, and inductance for accurate readings on small capacitors and inductors. The LC77 is pro tected from external voltages applied to the test leads by a fuse in the TEST LEAD JACK and special circuitry which locks out all test buttons when voltage is sensed on the test leads.
Battery operation makes the LC77 completely portable for on-location troubleshooting in all types of servicing from industrial equipment to avionics to cable fault locating. An optional SCR & Triac tester extends the LC77 test .capabilities to provide a fast, accurate test of these components. The LC77 may be interfaced into any IEEE 488 Bus system for fully automatic, computer controlled testing in a laboratory or incoming inspec tion area.
Specifications
DIGITAL READOUT
TYPE: .45”, 6 digit, 7 segment LCD READINGS: Fully autoranged with auto decimal place
ment. One or two place holding zeros added as needed to provide standard value readouts of pF, uF, F, uH or mH.
ANNUNCIATORS: pF, uF, F, uH, mH, H, uA, mA, %,
V, kft, MA, OHMS, RINGS, SHORT, OPEN, WAIT, GOOD, BAD.
CAPACITORS (Out of circuit)
Dynamic test of capacity value is determined by measuring one RC time constant as capacitor is charged to 4-5 V through:
1.5 Megohms for 0 - .002 uF
15 Kilohms for .002 uF - 2 uF Values above 2 uF are charged with a constant current of:
60 mA for 2uF - 2000uF
416 mA for 2000 uF - 19.99 F Maximum voltage across capacitors larger than 2000 uF limited to 1.75 V.
ACCURACY: + / — 1% + /- lp F 4- /- 1 digit for values
to 1990 uF. 4-/ —5% 4 - / - .1% of range full scale for
values 2000 uF to 19.99 F. RESOLUTION AND RANGES: 1.0 pF to 19.99 F, fully
autoranged:
.1 pF —
IpF —
.00001 uF —
.0001 uF —
.001 uF —
.01 uF —
1.0 pF to
200 pF to
0.00200 uF to
0.0200 uF to
0.200 uF to
2.00 uF to
199.9 pF 1999 pF
0.01999 uF
0.1999 uF
1.999 uF
19.99 uF
6
.luF —
luF — 200 uF
10 uF —
100 uF —
.001F —
.01F — 2.00 F
20.0 uF
2,000 uF to
20,000 uF
0.200 F
to to
to to to
199.9uF 1,999 uF
19,990 uF
199,900 uF
1.999 F
19.99 F
CAPACITOR LEAKAGE
READOUT: User selectable between leakage current
and resistance. ACCURACY: + / - 5% + / -1 digit. APPLIED VOLTAGE: Keyboard entry; 1.0 to 999.9
volts in . 1 volt steps; accuracy +0 -5%. Short circuit
current limited to 900mA, power limited to 6 watts. RESOLUTION AND RANGES: .OluA to 20 mA, fully
autoranged:
.O luA —. 0.01 uA to 19.99 uA
.l uA — 20.0 uA to 199.9 uA
1 uA — 200uA to 1999uA
.01mA— 2.00 mA to 19.99 mA
CAPACITOR ESR (Test patent pending)
ACCURACY: +/ -5% + /- 1 digit. CAPACITOR RANGE: 1 uF to 19.99 F.
RESOLUTION AND RANGES: .10 ohm to 2000 ohms,
fully autoranged:
.01 ohm — 0:10 ohms to '1.99 ohms
.lohm — 2.0ohms to 19.9ohms
1 ohm — 20 ohms to 199 ohms
10 ohm — 200 ohms to 1990 ohms
CAPACITOR D/A (U.S. Patent #4,267,503)
ACCURACY: + /- 5 counts. RANGE: 1 to 100%.
CAPACITOR RANGE: .01 uF to 19.99 F.
RINGING TEST
A dynamic test of inductor quality determ ined by apply ing an exciting pulse to the inductor and counting the number of cycles the inductor rings before reaching a preset damping point. (U.S. Patent # 3,990,002) INDUCTOR RANGE: 10 uH and larger ,-non-iron core ACCURACY: -i- / — 1 count on readings between 8 and
13. RESOLUTION: + /-1 count. EXCITING PULSE: 5 volts peak; 60 Hz rate.
GENERAL
TEMPERATURE: Operating range: 32c to 104°F (0°
to 40°C) Range for specified accuracy (after 10
minute warmup): 50° to 86°F (10° to 30°C)
POWER: 105-130V AC, 60Hz, 24 watts max. with
supplied PA251 power adapter. Battery operation with optional BY234 rechargeable battery. 210-230V AC operation with optional PA252 Power Adapter.
AUTO OFF: Removes power during battery operation
if unit sits idle longer than 15-20 minutes.
BATTERY LIFE: 8 hours typical inductor testing; 7
hours typical capacitor testing. SIZE: 6” x 9” x 11.5” (15.2cm x 22.9cm. x 29.1cm) HWD WEIGHT: 6 lbs. (2.7kg) without battery, 7.6 lbs (3.4kg)
GOOD/BAD INDICATION: Functions on all tests. Re
quires user input of component type and value, or
input of desired limits.
IEEE: Requires the use of Sencore IB72 Bus Interface
Accessory..
The following interface codes apply: SHI, AH1, T8,
L4, SRO, RLO, PPO, DCO, DTC, CO. All readings are test accuracy 4-/-.1 count.
INDUCTORS (In or out of circuit)
A dynamic test of value determined by measuring the EMF produced when a changing current is applied to the coil under test. (U.S. Patent # 4,258,315) CURRENT- RATES: automatically selected
50 mA/uSec —
5 mA/uSec —
.5 mA/uSec —
50 m A/mSec —
5mA/mSec —
.5 m A/mSec —
.05 mA/mSec — 1.8H
ACCURACY: +/- 2% +/ - I digit RESOLUTION AND RANGES: .10 uH to 20 H, ful
autoranged
.01 uH — 0.10 uH
.1 uH —
1 uH —
.001 mH —
.01 mH —
.ImH —
1 mH —
.001H —
.01H —
OuH to 18 uH
18 uH
180 uH to 1.8 mH
1.8 mH : 18 mH to 180 mH
180 mH
20.0 uH 200 uH
1.000 mH
2.00 mH
20.0 mH 200 mH
1.000 H
2.00H
to 180 uH to to
to 19.99 H
to to to to to to to to to
19.99 uH
199.9 uH 999 uH
1.999 m il
19.99 mH
199.9 mH 999 mH
1.999H
19.99 H
18 mH
1.8 H
Specifications subject to change without notice
ACCESSORIES
SUPPLIED:
39G143 Test Leads 39G144 Test Lead Adapter 39G201 Test Button Hold Down Rod 64G37 Test Lead Mounting Clip PA251 AC Power Adapter/Recharger
OPTIONAL:
39G85 Touch Test Probe FC221 Field Calibrator
BY234 Rechargeable Lead Acid Battery
SCR250 SCR/Triac Tester CC254 Carrying Case CH255 Component Holder CH256 Chip Component Test Lead
IB 72 Bus Interface Accessory
PA252 220V AC Power Adapter/Recharger
7
Controls
1. COMPONENT TYPE select buttons. Use with TEST buttons (4), and COMPONENT PARAMETERS buttons (6) for component limit testing.
a. - e. capacitor type buttons - Use with other beige
color coded capacitor buttons (4a - d) and (6m - o).
f. SPARE - Provides a spare button to allow for
future component types and internal memory up dates.
g. - i. Inductor type buttons - Use with other blue
color coded inductor buttons (4e - f) and (6s - u).
2. LCD DISPLAY 2a. SHORT - Indicates that test leads, or component
connected to test leads, are shorted when LEAD ZERO OPEN button (9a) or CAPACITOR VALUE TEST button (4a) is pushed.
2b. OPEN - Indicates that test leads, or component
connected to test leads, are open when LEAD ZERO SHORT button (9b) or INDUCTOR VALUE TEST button (4e) is pushed.
2c. WAIT - Indicates internal circuits are discharg
ing after CAPACITOR LEAKAGE TEST button (4c) is released. Also indicates external voltage on test leads. All tests are locked out while WAIT indicator is on.
2d. DIGITAL READOUT - Indicates value of test
result. Last two digits are place holders and indi cate 0 on large readings. Displays error message if error condition exists.
2e. READING ANNUNCIATORS - Automatically
light to qualify the reading displayed in the DIGI
TAL READOUT (2d).
2f. GOOD - Indicates that component meets pre-de-
fined tolerances for the test selected by TEST but ton (4).
2g. BAD - Indicates that the component does not
meet the pre-defined tolerances for the test selected by TEST button (4).
3. A PPLIED VOLTAGE LCD DISPLAY - Displays the amount of leakage voltage to be applied to the TEST LEAD (10) when the CAPACITOR LEAKAGE button (4b) is pressed. Voltage is selected using COMPONENT PARAMETERS keypad (6a-l & 6r).
5. CAUTION INDICATOR LED - Blinks as a warning when leakage voltage is set to 25 volts or higher, as indicated on APPLIED VOLTAGE LCD DISPLAY (3). Voltage is only present at test leads when CAPACITOR LEAKAGE test button (4c) is depressed.
6. COMPONENT PARAMETERS keypad - Use to enter parameters for limit testing.
a-k. NUM ERIC INPUT - Use to enter numerical
value portion of parameters. Use with COMPO NENT PARAMETERS buttons (m-u).
1. CLR - Push once to clear NUMERIC INPUT entry. Push twice to clear all parameters and COMPO NENT TYPE switches (1).
m-G. CAPACITOR VALUE MULTIPLIER - Use
after NUMERIC INPUT entry (6a-k) to enter capacitor value. Push to recall entered value.
p-q. PERCENTAGE buttons - Use after
NUMERIC INPUT entry (6a-k) to enter compo nent tolerance. Push to recall entered value.
r. VOLTS - Use with NUMERIC INPUT (6a-k) to
select desired test voltage for capacitor leakage tests.
s-u. INDUCTOR VALUE MULTIPLIER - Use
after NUMERIC INPUT entry (6a-k) to enter in ductor value. Push to recall entered value.
7. PULL CHART - Provides simplified operating in structions and quick reference tables.
8. LEAKAGE Switch a. CURRENT - Selects readout of leakage current
in uA or mA when CAPACITOR LEAKAGE but ton (4c) is depressed.
b. OHMS - Selects readout of leakage in ohms when
CAPACITOR LEAKAGE button (4c) is depressed.
9. LEAD ZERO Switch
a. OPEN - Use with CAPACITOR VALUE button
(4a) and open test leads to balance out test lead capacitance.
b. SHORT - Use with INDUCTOR VALUE button
(4e) and shorted test leads to balance out test lead inductance.
4. TEST buttons a. CAPACITOR VALUE - Depress to test capacitor
value.
b. DIELECTRIC ABSORP - Depress to read per
centage of dielectric absorption.
c. CAPACITOR LEAKAGE - Depress to test
capacitor leakage after the capacitor working vol tage is entered with the COMPONENT PARAMETERS keypad (6).
d. CAPACITOR ESR - Depress to test capacitor
ESR.
e. INDUCTOR VALUE - Depress to test inductor
value.
f. INDUCTOR RINGER - Depress for ringing (qual
ity) test on coils, yokes/flybacks and switching transformers after selecting inductor type with COMPONENT TYPE switches (lg-i).
10. TEST LEAD INPUT JACK - Provides a connec
tion for attaching supplied test leads (17) or optional
CHIP COMPONENT TEST LEADS (30). Unscrew jack
for access to protection fuse.
11. POWER Switch
a. OFF - Removes power from all circuits.
b. AUTO OFF - Provides power for approximately
15 minutes after auto off circuitry is reset. Auto off is bypassed when LC77 is powered from the AC Power Adapter.
c. ON & BATT TEST - Turn unit on and reset auto
off circuitry. Remaining battery life is displayed in LCD DISPLAY (2d).
8
2 c v
WAIT
2b— OPEN
2a
-SHORT
Fig. 1 — Location of front panel controls and features.
O O O O O O S F m H m A K Q G ° 6 D
U . U . U . U . U . U .
Fig. 2 — LCD annuncia tors.
r in g s % n BAD
-------
29
Supplied Accessories
17. TEST LEADS (39G145) - Special low capacity cable with E-Z Hook® clips. Connect to TEST LEAD
INPUT (10).
18. 39G144 TEST LEAD ADAPTER (39G144) - Use to adapt TEST LEADS (17) to large, screw terminal capacitors,
19. TEST BUTTON HOLD DOWN ROD (39G201) - Use to hold CAPACITOR LEAKAGE button (4c) depre ssed when reforming capacitors.
20. TEST LEAD MOUNTING CLIP (64G37) - Use to hold Test Lead when not in use.
21. POWER ADAPTER (PA251) - Plugs into POWER
INPUT (16) to power unit from 105-130 VAC line. Also recharges the (optional) BY234 Battery when installed inside the LC77.
Fig. 4 — Supplied Accessories.
OPERATIO N
Introduction
Before you begin to use your LC77 “Auto-Z”, take a few minutes to read through the Operations and Appli cations sections of this manual and acquaint yourself with the features and capabilities of your instrument. After you have familiarized yourself with the general operation of the LC77, most tests can be performed with the information on the front panel.
AC Power Operation
For continuous bench operation the LC77 is powered from any standard 105-130V (50-60 Hz) AC line using the PA251 Power Adapter. When 220V AC operation is required, power the LC77 with the optional PA252 220 VAC Power Adapter. Connect the Power Adapter to the POWER IN JACK located on the rear of the
LC77, as shown in Figure 6. The power adapter serves as a battery charger to re
charge the (optional) BY234 battery when it is installed in the unit. The BY234 may be left installed in the LC77 at all times without danger of over charging. Connecting the Power Adapter bypasses the auto-off circuitry in the LC77 and allow continuous, uninter rupted operation.
------------------
Using an AC a dapter other than the PA251 or PA252 may cause damage to the LC77, may cause the optional b attery (if installed) to im
properly charge, or may cause measurement
errors on low values of components. Only use a Sencore PA251 or PA252 Pow er A dapter for AC operation.
To operate the LC77. from an AC line:
1. Connect the AC line cord of the power adapter to an adequate source of AC power.
2. Connect the power adapter lead to the POWER
INPUT JACK on the back of the LC77, as shown in
figure 6.
3. Push the POWER switch on the LC77 up to the ON & BATT TEST position and release. The WARNING
LED will momentarily blink to indicate it is operational
and the displays will reset and read zeros.
4. The LC77 is immediately ready for use. If precise measurements are required, allow the unit to operate
for 10 minutes to reach specified accuracy.
WARNING
------------------
Fig. 6 — Connect the PA251 to the 12 V DC input for
AC bench operation and to rechar ge the optional bat
tery.
-------:-------------
The CAUTION INDICATOR LED m ust
momentarily flash when the POWER switch
is first turned on and moved from the OFF to
the ON & BATT TEST position. Failure of the
light to flash indicates a problem with the
LED or safety circuits. DO NOT operate the LC77 in this condition, since it exposes the operator to dangerous voltages without adequate warning.
WARNING— :
............
..........
Battery Operation
The LC77 is designed to operate as a completely port
able unit with the optional BY234 rechargeable battery installed. The operation of the LC77 when it is battery powered is the same as when it is AC powered. The length of time the “Auto-Z” will operate before the bat tery needs recharging depends on several factors: 1. the test functions used; 2. temperature; 3. battery age.
Leakage tests place the heaviest current drain on the battery - greater currents result in shorter battery life
between recharging. Value tests place the least drain on the battery. For typical operation, the LC77 provides
approximately 7 hours of complete capacitor testing
(value, ESR, D/A and leakage), and 8 hours of complete
12
Notes
11
inductor testing (value and ringing). These times, of course, will vary with temperature and battery age.
As the temperature of the battery decreases, its capac
ity also decreases. The operating time between recharg ings decreases at the rate of approximately 1 hour for every 20 degrees F drop in temperature below 70°F. The BY234 battery is a sealed, lead-acid type which requires no maintenance other than recharging. As a battery ages, it will require more frequent rechargings. If used properly, the BY234 will provide several years
of service before needing replacement.
You can maximize the lifetime of the BY234 several ways: 1. Never allow the battery to deeply discharge. The LC77 has a built-in battery test and low battery shut off circuitry. Check the remaining charge period ically and recharge the battery before the low battery circuit shuts the unit off. 2. Keep the battery fully charged. The BY234 will not be harmed if it is left installed in the LC77 during AC operation. Instead, this will keep the battery fresh and ready for use and will actually lengthen its useful lifetime, 3. Recharge the battery before using it if it has sat idle for more than a couple of weeks. Lead-acid batteries normally lose some of their charge if they sit idle for a period of time.
Fig. 7 — The optional BY234 is installed in the LC77 for por table ope ration.
To install the optional BY234 Battery:
----------------
Observe these precautions when using lead- acid batteries:
X. Do not dispose of old lead-acid batteries in fire. This may cause them to burst, spraying acid
through the air.
2. Do not short the “ 4-” and “ — ” term inals to geth er. This will burn open internal connec tions, making the battery useless.
3. Do not charge 12 volt lead-acid batteries with a voltage greater than 13.8 VDC. High
charging voltage may damage the battery or cause it to explode.
4. Do not drop the battery. While lead-acid bat
teries are well sealed, they may break if dropped
or subjected to a strong mechanical shock. If the battery does break and the jelled electrolyte leaks out, neutralize the acid with baking soda and water.
5. Do not charge the battery below 0° C or above +40° C.
—WARNING.
---------
— ------
1. Open the BATTERY COMPARTMENT COVER lo cated on the rear of the unit by unscrewing the thumbscrew. Fold the cover down on its hinge.
2. Slide the battery end that does not have the connector attached into the battery compartment. (The wire should be facing out after the battery is in place.)
3. Connect the plug from the battery to the jack inside the battery compartment.
4. Close the battery compartment cover and tighten the thumbscrew to hold the door and batteries in place.
Not e: Rec harge th e BY234 overnight before usi ng it f or
the first time.
Battery Test
The LC77 has a built-in battery test feature which shows the remaining battery recharge. A reading of 100% indicates that the battery is fully charged. As the battery charge is used up, the reading will drop in 10% intervals. The low battery circuits will turn the unit off shortly after the battery test reading drops to 0%, and before the battery level drops too low for reliable operation. The LC77 never fully discharges the battery which helps extend the life of the BY234.
13
To perform the battery test:
A u to O ff
1. With a BY234 installed, move the POWER switch to the ON & BATT TEST position.
2. Read the percentage of remaining battery charge in the LCD DISPLAY, as shown in figure 8.
3. If the reading shows 0%, the unit may not operate, or operate for just a short time since the low battery circuit turns the LC77 off at this battery level.
To conserve battery charge, the LC77 contains an auto off circuit. This circuit keeps the batteries from running down if you should forget to turn the unit off, but keeps the “Auto-Z” powered up during use. The auto off circuit will shut the LC77 off after approximately 15 minutes if none of the front panel buttons have been pushed. Pushing any COMPONENT TYPE button, COMPO NENT PARAMETERS button, TEST button, or momentarily moving the POWER button to the ON & BATT TEST position will reset the auto off circuits. The auto off circuits are bypassed when the LC77 is operated from the PA251 AC Adapter/Charger.
To operate the LC77 using the optional BY234 bat tery:
1. Install the BY234 battery into the LC77 battery com partment.
NOTE: If you are using the BY234 for the first time, be sure to charge the battery before using the LC77. Though factory tested, the BY234 may not be charged when you receive it.
2. Push the POWER switch to the ON & BATT TEST position and release. The WARNING LED will momen tarily blink to indicate it is operational and the displays will reset and read zeros.
Fig, 8 — Push the Power switch to "On & Batt Test”
to r ead the remaining battery charge.
Recharging the Battery
The BY234 battery should never be allowed to remain discharged for more than a few hours, since this will shorten its lifetime. The battery must be recharged whenever the battery test reads 0%. However, you should recharge the battery more often than this to lengthen the battery’s lifetime and keep the LC77 ready for portable use at all times.
To recharge the battery, simply leave it installed inside the LC77 while the unit in connected to the PA251 AC Adapter/Charger and the Power Adapter is connected to a source of AC power. The charging time required to return the battery to 100% depends on how far it is discharged. The battery will trickle charge while the LC77 is in use and powered from the AC adapter, but it will recharge the quickest if the POWER switch is in the “OFF” position. Normally, a battery will com pletely recharge in about 8 hours with the POWER switch “OFF”.
3. The LC77 is immediately ready for use. If precise measurements are required, allow the unit to operate for 10 minutes to reach specified accuracy.
-----:---------
The CAUTION' INDICATOR LED must mom entarily flash when the POWER switch is m oved from the OFF to the ON & BATT TEST position. Failure of the light to flash indicates a problem w ith the LED or safety circuits. DO NOT operate the LC77 in this con dition, since it exposes the operator to dang er ous voltages w ithout adequate warning.
------
WARNING
---------
■■■■■
..........
Test Leads
The test leads supplied with the LC77 (39G143) are made of special, low capacity coaxial cable. Using any other cable will add extra capacity to the meter circuits, which may not be within the range of the lead zeroing circuits. Attempting to zero the leads with another, higher capacitance cable connected will cause the LCD DISPLAY to show the message error. This indicates that the value is beyond the zeroing limits of the LC77.
If the test leads ever require replacement, new leads (part # 39G143) may be ordered directly from the: SEN CORE SERVICE DEPARTMENT at 3200 Sencore Drive, Sioux Falls, SD 57107.
14
Test Lead Mounting Clip
A TEST LEAD MOUNTING CLIP (64G37) is supplied with the LC77. This clip is useful to hold the test leads out of the way when not in use, but keeps them ready and within reach at any time. The mounting clip may be attached on the top of the LC77, on the side of the handle, or wherever it is most convenient. To mount the clip, peel off the backing, place the clip in the desired location and press it firmly in place.
Fig. 10 — The 39G144 Test Lead Adapter allows large, screw-ter minal capacitors to be con nected to the LC77.
Fig. 9 — The test lead mounting clip holds the test leads out of the way, yet ready for use at anytime.
NOTE: Do not mount the TEST . LEAD MOUNT ING CLIP to the sides of th e “Auto- Z” as this will interfere
with the handle mov ement.
Test Lead Adapter
Some larger value electrolytic capacitors have screw terminals rather than the conventional wire leads or
solder terminals. To connect the LC77 to these capacitors you will need to use the supplied 39G144 TEST LEAD ADAPTER. The TEST LEAD ADAPTER converts the E-Z Hook® clips of the test leads to alligator clips which will clamp onto the large screw terminals. A mounting clip on the back of the LC77 stores the TEST LEAD ADAPTER when it is not in use.
To use the TEST LEAD ADAPTER:
1. Connect the red E-Z Hook® of the LC77 test lead to
the red TEST LEAD ADAPTER terminal.
2. Connect the black E-Z Hook® to the black adapter terminal.
3. Connect the red TEST LEAD ADAPTER lead to the “ + ” capacitor terminal, and the black lead to the terminal.
4. Test the capacitor in the usual manner.
Test Lead Fuse
A 1 amp, Slo-Blo (3AG) fuse is located in the TEST LEAD input jack on the front of the “Auto-Z”. This fuse protects the unit from accidental external voltage or current overloads. The fuse may need replacement if the following conditions exist:
BLOWN FUSE CONDITIONS:
- Display reads “OPEN” during inductor lead zeroing
- Display reads “OPEN” during inductance test
- Ringing test reads “0”
- ESR test reads “Error 7”
- No Leakage readings
- Readings do not change with test leads open or shorted Refer to the maintenance section, located at the back
of this manual for information on replacing the test lead fuse.
15
Leading Zeroing
The test leads connected to the LC77 have a certain amount of capacitance, resistance, and inductance which must be balanced out before measuring small value capacitors and inductors or before measuring
capacitor ESR. The test lead impedance should be zeroed when the LC77 is first turned on. It will remain zeroed as long as the unit is powered on. If the LC77 is battery operated and is turned off by the Auto Off circuits, however, the leads must be rezeroed.
6. Move the LEAD ZERO switch to the “Short” position, arid release when a “ — ” begins to move through the
display.
CAPACITOR-INDUCTOR ANAL’
COMPONENT TYPE
COMPONENT PARAMETERS
—IIr™
0000000
i B Q 0 0 0 0 0 0 0
To zero the test leads:
1. Turn the LC77 on by momentarily pushing the POWER switch to the ON & BATT TEST position.
2. Connect the test leads to the TEST LEAD INPUT
jack on the front of the “Auto-Z”.
3. Place the open test leads (with nothing connected) on the work area with the red and black test clips next
to each other, but not touching.
4. Move the LEAD ZERO switch to the “Open” position. Release when a “ — "begins to move through the display,
5. Connect the red and black test clips together.
Entering Component Data
S E N C O R E
AUTO - Z
TEST ICAO L£AD2£BO LEAKAGE
I CUKfltNT .
A WARNING: T** ic
optfra tf td by d v «n ia p«ri
oMy. i M U g * B utton 2!
• - *-• Ught
Fig. 11 — Th e impedence of the test feads is balanced out with the L EAD ZERO button.
CAPACI TOR - INDUCTOR ANALYZER
COMPONENT PARAMETERS
nu m e r i c i n p u t en t er / rec a l l
o
ALUMINUM
IYTICS
0
CEHAtffC
CAPS
0
COILS
OMPONENT TYPE
o
DOUBLE
TANTALUM
LAYER
LYTICS
YOKES &
FLYBACKS
5
0
SWITCHING XFQRME8S
[O
I ALL OTHER I CAPS
0
CAPS
SPARE
Fig. 12— Controls used for enter ing c ompo nent data.
To use the LC77 to perform the automatic Good/Bad tests explained later in this manual, you must enter data about the component under test into the LC77 “Auto-Z” (All component tests can be performed with
pF PL?
CLR
mh
PULL CHART F—
out entering component data if automatic Good/Bad test indications are not desired). The component data tells the LC77 the “ideal” parameters necessary to make the Good/Bad determination.
16
..........
mH
_______
The component data which can be entered into the LC77 includes: component type, value, tolerance and rated
working voltage for capacitors, and component type,
value, and tolerance for inductors and coils. These parameters are usually marked on the component, or
can be determined by looking the component up in a parts list or replacement guide. The Applications sec tion of this manual contains information on how to
identify capacitor and inductor types.
NOTE: All component d ata can be cleare d by pushing
the “CLR” button on the gray COMPONENT KEYPAD twice.
To Enter Component Type:
NOTE: The compo nent type swit ches t ell th e LC77 wha t
kind of component is b eing t este d.
1. Press the desired COMPONENT TYPE button. Use the beige color coded buttons when checking capacitors and the blue buttons when checking inductors.
2. A red LED indicator in the corner of the COMPO NENT TYPE button lights when that button is selected.
To Enter Component Value:
1. Enter a number, up to 3 significant digits, equal to
the value of the capacitor or inductor. (Example: “123”.
or “123000.”). Each digit will appear in the display as a key is pushed.
a. The LC77 rounds the entry down if yo u enter a
number having more tha n 3 si gnificant d igi ts (Exam
ple : “1239” bec ome s “1230”).
b. TheLC77accepts numbers up to 6places before the decimal. (Example: “10 000 0”). E ntries larger th an this reset to 0.
c. TheLC77 accepts numbers up to 5 pla ces aft er t h e
de cim al for numbers le ss than 1. (Exam ple: “0.00001”). Entries smaller than this re sult in “Erro r
2” . '
d. All unneces sary place holder dig its a re drop ped,
(Examp le: “.06 700” becomes “.067 ”).
e. Pu sh the “CLR” b utton once to clea r the va lue entry
a nd st art over.
To Enter Component Tolerance:
1. Enter a 1, or 2 or 3 digit number up to 100 which equals to the “ + ” value tolerance of the capacitor or inductor. Do not use a decimal.
2. Press the white “ + %” PERCENTAGE button.
3. Enter a 1 or 2 digit number up to 99 which equals to the value tolerance of the capacitor or inductor.
Do not use a decimal.
4. Press the white PERCENTAGE button.
5. To check the entered percentage, press the white “ -r %” or “ -%” button at any time.
SENCORE
COMPONENT TYPE
o G
G-O
G
2-
O
CAPAC ITO R- IND UC TO R ANALYZER
a
©ENCORE
COMPONENT PARAMETERS
H H Q E D ' '
□ □ □ 0 0 0 H
b
CAPACITOR • INDUCTOR ANALYZER
2. Enter the desired CAPACITOR VALUE MULTIP LIER or INDUCTOR VALUE MULTIPLIER.
a. The c apacitor value range is 1 pF to 19.9 F. The
inductor value range is .1 uH to 19.9 H. Ente ring
values beyond this ra nge causes an “E rror 2”.
b. The LC77 accepts non-convention al value n ota
tions, such as “.00001F”, 00002 uF” or “100000pF”
3. After entering the multiplier, the display momentar ily shows the entered value and multiplier before re
turning to a “0000” reading. The LC77 is now ready
for the next parameter entry.
4. To check the entered capacitor value at any time, push any beige colored CAPACITOR VALUE MULTIP LIER button. To check the entered inductor value push
any blue colored INDUCTOR VALUE MULTIPLIER
button.
5. To change an entered value parameter, repeat steps
1 & 2.
CAPACITOR - INDUCTOR ANALYZES
n n
COMPQUH
MT P AR AWTjERS
L UJ
0000
0000
□ □ □ 0
d
Fig. 13 — To enter compon ent data select the COMPO NENT TYPE switch which corresponds to the compo nent being tested (a). Next, enter the component value (b) and value tolerance (c). Finally, if te sting a
capacitor, enter the rated working voltage (d).
17
To Enter Leakage Voltage:
1. Enter the desired voltage from 1 to 999.9 using the gray keys on the NUMERIC INPUT keypad, A decimal, followed by one digit may be entered, but is not neces sary.
2. Push the white “V” key to enter the voltage. The voltage will appear in the APPLIED VOLTAGE LCD DISPLAY. For values greater than 25 volts the red CAUTION INDICATOR LED will blink.
NOTE: The voltage is appl ied to the component Test Leads when the CAPACITOR LE A K AG E test butt on is pus hed.
3. To enter a different voltage, repeat steps 1 & 2.
Error Codes
Error 3 - Entered Value Beyond Range Of Test - The component parameter entered via the keypad or IEEE is beyond the limits of the automatic good/bad test. The component may still be able to be tested, but not for a good/bad indication.
Possible causes:
1. Performing an ESR test with a capacitor value of less than 1 uF entered.
2. Performing a D/A test with a capacitor value of less than .01 uF entered.
3. Performing an INDUCTOR RINGER test with an inductor value of less than 10 uH entered.
E rror 4 - Value Beyond Zeroing Limit - The amount of inductance or capacitance at the TEST LEAD INPUT is beyond the range of the zeroing circuits. An open (greater than 20 Kilohms) or shorted (less than 1 ohm) test lead will cause the “OPEN” or “SHORT” annun ciator to come on, rather than produce an “Error 4”.
Several error conditions may occur while using the LC77 which cause an error message to appear in the LCD display. These are usually caused by small errors
in the operation of the LC77, although severely defec tive components may also cause certain error condi tions. The error conditions are explained below.
E rror 1 - Component Type Selection E rro r - This error occurs when a component test is attempted, and either an incorrect COMPONENT TYPE switch is selected for the test, or no COMPONENT TYPE switch is selected when required.
Possible causes:
1. Performing a capacitor test with an inductor COMPONENT TYPE
switch selected.
2. Performing an inductor test with a capacitor COMPONENT TYPE
switch selected.
3. Performing the INDUCTOR RINGER test without an inductor
COMPONENT TYPE switch selected.
4. Performing any component test with the “Spare” capacitor COM
PONENT TYPE button selected.
Error 2 - Entered Value Beyond Range of Unit -
The component parameter entered via the keypad or
IEEE is beyond the measuring range of the LC77.
Possible causes:
1. The capacitance at the TEST LEAD INPUT is greater than 1800 pF.
2. The inductance at the TEST LEAD INPUT is greater than 18 uH.
8. The resistance at the TEST LEAD INPUT is greater than 1 ohm.
Error 5 - ‘No Voltage E ntered - This error occurs when the CAPACITOR LEAKAGE button is pushed and no test voltage has been entered.
Error 6 - Invalid IEEE Command - An improper command was sent to the LC77 via the IEEE bus.
Possible causes:
1. Sending a command that is not recognized by the LC77.
2. Wrong command syntax.
NOTE: Ref er to the IEEE 488 Bu s Ope ration sec t i on of this manu al for infor mation on usi ng the “Auto-Z” with
IEEE contr ol.
E rror 7 - Component Out Of Test R ange - The com ponent under test exceeds the limits of the test which was attempted.
Possible causes:
Possible causes:
1. Entering a capacitance value greater than 19.9 Farads, or less
th an 1 picofarad.
2. Entering an inductance value greater than 19,9 Henrys, or less
th an .1 microhenrys.
3. Entering a leakage voltage greater than 999.9 volts.
4. Entering a tolerance percentage greater than 4-100%, or less than
- 99%. ,
5. Entering a tolerance percentage that includes a decimal.
NOTE: E ntering a leakag e voltage les s t han 1 volt wi ll
set th e leakag e supply to 0 volts.
1. Measuring ESR of a capacitor having a value less than 1 uF.
2. Measuring capacitance value on an extremely leaky capacitor.
3. Attempting a capacitor value test with 1 ohm to 2 Megohms of
resistance connected across test leads.
18
Capacitor Testing
S E N C O R E AU TO -Z
n n n n
U.U.U.U. m% n
NUMERIC INPUT ENTER / RECALL
(MODEL LC 77
Fig. 14— Controls used for capacitor p arameter tests.
CAPACIT OR - INDUCTOR ANALYZER
COMPONENT PARAMETERS
CLR
LEAKAGE
CURRENT
OHMS
PULL CHART
TEST
The LC77 “Auto-Z” checks capacitors for value from
1.0 pF to 20 Farads in 12 automatically selected ranges. The automatic features of the LC77 “Auto-Z” allow you to perform two levels of automated capacitor testing: basic parameter testing, and automatic good/bad test ing. For basic parameter testing, you simply connect the component to the test leads and push the test button. The LC77 measures the capacitor and displays the test result. You must look up the values of leakage, ESR and dielectric absorption in a table to determine if the capacitor is good or bad.
For automatic good/bad testing, you first enter the parameters of the capacitor before performing the test. Then the LC77 will display the test results alofig with
a good/bad indication of the capacitor. Only selected parameters need to be entered into the LC77, depending upon which tests you desire a good/bad readout for.
Capacitance M easurement Accuracy
The LC77 measures the RC charge time as the capacitor
is charged through a precision resistor. This gives the
most accurate measurement of true capacity available.
Capacity values measured with the “Auto-Z” may or may not exactly match readings on other instruments
which use a different measuring technique. Bridges, for example, measure capacitive reactance using an AC
signal. Capacitive reactance changes with frequency. Therefore, two bridges operating at different frequen
cies will give different capacity readings.
Electrolytic capacitors may normally read up to 50% higher than their marked value when measured with the LC77. This is because electrolytics are marked ac
cording to their value as measured on an AC-type im
pedance bridge. The value of an electrolytic changes
greatly with the measurement frequency. This should cause no problem in determining if an electrolytic capacitor is good or bad, since most electrolytic capacitors have up to 80% value. The capacitor should read close to its marked value, or within tolerance when checked with the LC77. In addition, electrolytics most commonly fail due to leakage, dielectric absorption, or ESR. When an electrolytic does change value, the value drops far below the marked value.
The LC77 “Auto-Z” is designed to measure capacitors out of circuit. Impedances found in the circuit will upset the “Auto-Z” readings. Capacitors can not be checked in circuit accurately or reliably with any test method. Capacitors in circuit however, may be tested by unsol dering one lead from the circuit. When doing this, be sure to remove power from the circuit. If the unit is AC
powered, unplug the AC line cord. Whenever possible,
remove the capacitor completely from the circuit to test it.
19
WARNING
Measuring Capacitor Value
When checking capacitors, remove the capacitor from circuit if possible. Otherwise, make sure the power is removed from the cir cuit and the AC line cord to the unit contain ing the capacitor is unplugged. Always con nect the capacitor to the LC77 test leads be fore depressing the CAPACITANCE VALUE test button.
_______
___
_____
Measuring Small Capacitance
Values In Noisy Environments
The sensitive “Auto-Z” measuring circuits may be af fected by large, outside signals (such as the AC fields
radiated by some lights and power transformers) when
small capacitance values are being measured. Special
circuits in the LC77 help minimize noise pickup and
stabilize the readings.
Measurements of small value capacitors in noisy envi
ronments may be further improved by grounding the
LC77 case to earth ground. When possible, power the
LC77 with the PA251 AC Adapter/Charger connected
to a properly grounded AC outlet. The PA251 Adapter/
Charger maintains the third wire ground shield and
keeps the noise away from the measuring circuits inside the “Auto-Z”.
To Measure Capacitor Value:
1. Zero the test leads, as explained on page 16.
2. Connect the capacitor to the test leads. If the capacitor is polarized, be sure to connect the black test clip to the terminal of the capacitor and the red test clip to the “ + ” capacitor terminal.
3. Depress the CAPACITOR VALUE button.
4. Read the value of the capacitor in the LCD DISPLAY.
NOTE : Th e “SHORT” annunciator appearing in t he LCD di splay when the CAPACIT OR VALUE butt on is
depressed indicates a res istance of 1 ohm. or less at the test leads. Check t he test leads. If they are no t s horted, the capacitor is bad.
Some capacitors will cause the display to read “Error
7”. These capacitors have too much leakage current to allow the LC77 to make a value check and should be considered bad.
Capacitor Parameter Testing
The LC77 checks capacitors for capacitance value, leak age, dielectric absorption and Equivalent Series Resis tance (ESR). These tests are made directly using the beige colored TEST buttons. Simply connect the compo nent to the test leads, push the desired TEST button, and read the test result in the LCD display. You can determine if the component is good or bad by comparing
the measured ESR and leakage values to the standard
values listed in the tables in this manual and on the Pull Chart underneath the LC77.
NOTE: Except for the cap acitor lea kage te st, no compo
nent parameters need to be enter ed to perf orm any capa citor para meter test. I f any blue Inductor COMPO
NENT TYPE butto n is select ed, error code “Error 1”
w ill appear in the LCD readout when you atte mp t to make a capacitor test . Push the “CLR" key on the gray
NU MERIC KEYPAD twice to clear any p arameter s.
The following procedures provide all the necessary in
formation required to perform the capacitor parameter tests. A more detailed description of each of the capacitor tests and failure modes can be found in the Applications section of this manual.
Fig. 15 — To measure capacita nce, connect the
capacit or to the te st ieads and push the CAPACITOR
VALUE button. The amount of capacity appears in the LCD display.
Measuring Capacitor Dielectric Absorption
Dielectric Absorption is often called “battery action” or “capacitor memory” and is the inability of the capacitor to completely discharge. While all capacitors have some minute amounts of dielectric absorption, electrolytics may often develop excessive amounts which affect the operation of the circuit they are used in.
20
To check a capacitor for dielectric absorption, press the
DIELECTRIC ABSORPTION button and compare the
value to the chart. A fully automatic good/bad test may
also be used to test for dielectric absorption. This test is explained in a later section.
charts. The capacitor is good if the measured leakage is be low the amount shown in the chart. A fully automa tic good/bad test may also be used to check capacitors for leakage. This test is explained in a later section.
To measure capacitor dielectric absorption:
1. Connect the capacitor to the test leads. If the capacitor is polarized, connect the red test clip to the “ + ” capacitor terminal and the black test clip to the
terminal.
2. Depress the DIELECTRIC ABSORPTION button. A
will appear and slowly move through the display
indicating that the test is in progress.
3. Read the percentage of dielectric absorption on the display.
4. Compare the measured D/A to the amount listed in
Table 1 for the capacitor type you are testing to deter
mine if the capacitor is good or bad.
NO TE: Depending on the capacitor’s value, type and
actual D/A, the LC 77 may, in a few cases, take up to 10
seco nds to displa y a reading.
Maximum Allowable Percent Of D/A
Capacitor type Maximum % of D/A Double Layer Lytic Meaningless. D/A may normally
be very high.
Aluminum Lytic
Tantalum Lytic 15%
15%
CAPA CIT OR- IND UCT OR ANALYZER
COMPONENT PARAMETERS
“ i
1
5
9 0
2
=5'l
7 j
6
" I
H M I f I ”
— . — —
i.. H *>; \ loicu-ci’wc
j[ | I 1! li Trr —
MH mw fl
CLR I
A WARNING. .
op ei a tv d b y s * e ef tn f
1000 vofts id imnJs wftev.
Bo not capaeiim ut
i&a kage t«st.
tAPAC-iTO*
Pr&ssmg leakage to-
rj
D
1
Fig. 16— To test capacitor leakage, enter the working voltage of the capacitor.
To measure capacitor leakage:
1. Connect the capacitor to the test leads. If the capacitor is polarized, connect the red test clip to the “ + ’’ capacitor terminal and the black test clip to the
terminal.
2. Set the LEAKAGE switch to the “Current” position to read the leakage of the capacitor in uA or mA.
i
Ceramic
All others
Refer to the Applications section of this manual for capacitor type identification.
Table 1— Maximum amounts of Dielectric Absorption.
10%
0%
Measuring Capacitor Leakage (In microamps)
Capacitor leakage occurs when some of the voltage from one plate flows (leaks) through the dielectric to the other plate. The amount of leakage current through the dielectric depends on the voltage applied across the plates. For this reason, always check a capacitor for leakage at (or as close as possible to) its rated voltage. Voltages up to 999.9 volts may by applied with the LC77.
To check capacitors for leakage, enter the working vol tage of the capacitor and press the CAPACITOR LEAK AGE button. Compare the measured leakage current to the maximum allowable amounts in the leakage
3. Enter the normal working voltage of the capacitor as explained earlier in the section “Entering Compo nent Parameters” on page 16.
-----------
-------
WARNING
-------------------
The LC77 is designed to be operated by a tech nically trained person who understands the shock hazard of up to 1000 volts applied to the test leads during the capacitor leakage test. DO NOT hold the capacitor in your hand, or touch the test leads or capacitor leads when making the leakage test.
4. Depress the CAPACITOR LEAKAGE button and
read the amount of leakage in the LCD display.
5. Compare the measured leakage to the maximum allowable amount listed in the Leakage Charts on pages 23 and 24 for the type, value, and voltage rating of the capacitor you are testing.
NOTE: By enter ing the Com ponent Type and Value
p aramet ers for th e capac itor, the LC77 will a utomati
call y display the measured leakage along wi th the same
good!h ad indic atio n as the L eakage Charts.
21
Voltage will be applied to the capacitor as long as the
CAPACITOR LEAKAGE button remains depressed,
and the leakage readings will decrease as the capacitor continues to charge. Some capacitors may take a few seconds to charge up to the applied voltage and may cause the display to overrange with a flashing “88.88 mA” display. Continue to depress the CAPACITOR LEAKAGE button until the leakage reading drops below the maximum allowable amount listed in the Leakage Chart.
When the CAPACITOR LEAKAGE button is released, the LC77 discharges the capacitor through a low value, high wattage resistor. The LC77 contains safety circuits which sense the voltage across the test leads. Therefore, when you release the CAPACITOR LEAKAGE button after checking a large value capacitor, or after applying a high leakage voltage, the display may show “Wait -
- - until the voltage is gone from the test leads. All data input and test buttons will be locked out until the display returns to “0000”.
LEAKAGE IN PAPER, MICA AND FILM CAPACITORS
Paper, mica and film capacitors should have extremely small amounts of leakage. Measuring any leakage when checking these types of capacitors indicates a bad component. The leakage reading may take 1-2 seconds
to show an accurate display while the capacitor charges,
LEAKAGE IN CERAMIC CAPACITORS
Leakage in ceramic capacitors is generally very low. Ceramic disc capacitors, however, may have small amounts of normal leakage. Ceramic disc capacitors
with voltage ratings above 50 WVDC should have less than 1 uA of leakage. Some discs with working voltages less than 50 WVDC may have a lower insulation resis tance, and therefore may show somewhat more leakage, depending upon manufacturer. In general, a 10 WVDC ceramic disc capacitor may show as much as 16 uA of leakage, and 25 WVDC ceramic disc may read up to
2.5 uA of leakage and still be considered good.
LEAKAGE IN ALUMINUM ELECTROLYTICS
Because of their larger value and higher leakage
characteristics, aluminum electrolytic capacitors may take several seconds to charge. The LC77 display may overrange (flashing 88.88 mA display) indicating the
charging current is greater than 20 mA while the
capacitor is charging. Table 2 shows the approximate time that you can expect the LC77 to overrange for a given capacitor value and applied voltage. After the LC77 stops overranging, the current will drop in prog ressively smaller steps as the capacitor charges. When the cap is fully charged, the leakage readings will change just a few digits up or down. You do not need to wait until an electrolytic capacitor is fully charged to determine if it is good. Simply keep the CAPACITOR LEAKAGE button depressed until the leakage reading falls below the maximum amount shown in the Leakage Charts.
Capacity (uF)
Table 2 — Meter Overrange time versus capacitor
valu e and applied voltage.
LEAKAGE IN TANTALUM ELECTROLYTICS
Tantalum electrolytic capacitors have much lower leak age than aluminum electrolytics of the same size and voltage rating. Therefore, tantalum lytics will give a leakage reading in a much shorter time than an aluminum lytic - typically within 2 to 5 seconds. Com pare the measured leakage with the amounts shown in the leakage charts to determine if the capacitor is good or bad.
LEAKAGE IN NON POLARIZED ELECTROLYTICS
Electrolytic capacitors which are non-pol arized should be checked for leakage in both directions. This requires that you measure leakage twice, reversing the LC77 test lead connections for the second test. The maximum
allowable leakage for a non-polarized electrolytic in either direction is twice that of a similar polarized elec
trolytic of similar capacitance value and voltage rating.
Leakage charts
The following leakage charts list the maximum amount of allowable leakage for the most common aluminum electrolytics and dipped soiled tantalum capacitors. These charts are also duplicated on the pull chart below the LC77. Good capacitors (as far as leakage is con
cerned) will measure lower than the amounts shown in the Leakage Charts. When measuring leakage, you do not need to wait for the readings to drop to zero or to its lowest point. The capacitor is good for any leakage reading which is lower than the amount shown in the chart.
Leakage values shown in Table 3 for aluminum elec trolytic capacitors are the worst-case conditions, as
specified by the Electronic Industries Association (EIA) standard RS-395. The values are determined by the formulas: L = 0.05 x CV (for CV products less than
1000) or L= 6 x square root of CV (for CV products
greater than 1000. (The CV product is equal to the
capacitance value multiplied by the voltage rating).
The tantalum capacitor leakage values listed in Table 4 are for the most common type of tantalum capacitors — dipped solid, type 3.3. These values are specified by EIA standard RS-228B, following the formula: L = 0.35
Maximu m Allowable Leakage (in Micro amps)
Standard Aluminum Electroiytic Capacitors
Capacity
in uF
1.5 V 3.GV 6.0V | 10V
1.0
1.5
2.2
3.3
4.7
6.8 10
15 5 5
22 33 47 68
100
150
220 330
470
680 192 271 383
1000 1500 2200 3300
4700 5Q 4
6800 10000 15000 22000 33000 47000
560C -:' 1739
68000
1000C0 1 2324
15000. 23-3
220 0CC ! 3 ^ 7
5 5 j 5 5 5 [ 5 5 5 5 5 5 5 5
5 5 5
5
5 10 I 20
8 15
11 17 33
25 35
V
232 285 *02
•345 422 697
606 735 1039
900 1C30 • 1541 1335 1593
|
1916'
5 5 5 5 5
5 ; 5
5
7
23
50
: 225
329 . :465 600 735 849 345
487 689
V2 1008
£57 12 >2 1565
■c?3
18 33 2570 2253
2459, 3*76 4490 5499 6350
2'< 0 3256 4648 £C25 437-
5 | 5
5 5 5 5 I 5 fi 5 | 8
7 10 14
J
30 45
218 281 267
319
569
:• : 844
1470
1300
2
j 30
3185
3B32
5592 6333
\#
5 5
5
11
•17 25 33 41 24 34
50 232
232 205 329
345 422 411 495
735
890 10 9C 1259 '.090 1301 ' '1593 1840
189“ 2324 2814 3447 4:13
494 S 6060 6997 7823 9256
eooc
7346 9000 3899
20V
15 V
5
5
5
5
5
5 5 5 5 7 9
10 13
ll
15 19
17
22 28
35 47 235
22'
192
268 330
345 398 44 5
457
504 552 65 3
606 703 782
S3C 1039
'335 1541
2212
1916 2324
2583
2S46
3286
3447
3980 4574
422 1 5C 33
5617 6504 . 7695 ,L 9198
8485 .9487
7345
25 V 35V
247
357
545
’ ■63 1407 1723 2039 2437 2057 2434 24-4 3000 3674 4450 5450
7039
x square root of CV. In a few applications outside of
consumer service, tantalum capacitors other than type
3.3 may be encountered. Refer to the manufacturers’ specifications for the maximum allowable leakage for these special capacitor types.
50V 100 V
5 5 5 5 5 j 8 5 5 e l 11 | 22 5 6 e
8 12 12 18 25 26 38 39 199
234 244 243 231 4-1 ?S3 350 355 424 435 526 529 645 770 920
925 <122 1375 ■643 2324 1665 1990
2927 3550
4347 5255 S293 6448
.. 8400
5
8 j 17 33
17
520
7 7"!
■.*06 1342
2903 41-3 3499
4243
5195
7707
i
j
1
\
|
200V 300V
5
23 34 22* . 271 50
2G8 232 32 3 402 281 338
.157
345
582 712
495
70Q
600
849 . :. 1039; • 1200
735
1033 ■ 1273
aso
1259 .1541 1780
^030 154 1 1888
1 34-3
isc:
155 5
2213 2710 3129
1357
2683 3236 4025
2814
398-3 4874
3447
5517 R937
4943 S G3C
643 5
7348
B899
j .
10 15
47
400V
20 25
15 23 30 38
44
33
5C .. 213 244
225
329
437
: 597
857.
2253
3236 3795
4374
5S7 0 6S93 7125
■'8570.
260
■ 313.
■ ■ 379 ■ 465
• 563 689 823
, 990 1106 ■ 1212
1470
t
2180 2602
4648 5628
8227
■ 9895
500V 600V
.....
19 9
291 ■ 319: 411 350 ■383. 424
' 520 563
629
' 771 ■ -844
• 920
■ 13 42 1643
'
1990
~ 2437
2909
3499 4243; 519 6 .. 5692
6293- 6893
7707
9198
I
...
1000V
30 50 45
232
218
- . 281
267.
345
• 495
465
600
689
890
1090
-cos
1301
• .. 1565 1470 1897 1800
2324
2180
2814 2670 3447 3186 4113 3332
4948 4648
. 6000
. . 7348
■ 8899
.8443
i
735
:
NOTE: No industry stand ards are available for component va lues in the shaded areas. These values have been
extrapolated from existing st anda rds and manufactur er s data. Ail vaiues not sh ade d are based on existing EIA
industry stand ar ds.
Table 3 — Maximum allowable leakage for aluminum e lectrolytics per EIA standards.
23
Dippe d Solid Tantalum Capacitors
Capacity 1,5V
1.0
1.5
2.2
3.3 4,7
6.8 10 15 22
33
47 68
100 150
220
330 470
680 1000 1 SCO
2200 3300 4700 6800
1.0
1.0 1.0 1.0 1.0 1.0
1.0 1.0 1.0
1.0 1.0 1.0 1.0 1.0
1.0 1,0 1.0
1.0 1.0 1.0 1.5 2.0
1.6
2.2 2.2 2.2 2.5 3,0
2.8 2.8
3.4 3.4 3.4 5.0 7.5
4.0
5.0 5.0 5.0
10 10 10
15 15 15
20 20 20 20
24 24
29 29
35 35 35 43 43 43 43 53 52 52 52 52 64 64
76 76 76
91
1000 0 111- 111
15000
. 136
22000
33000
47000 240
g
o
100000
150000
200000
164 201 201 201
289 350
■V: .V 429
■ 495 495
3,0V 6.0V
1.0 1.0
1.6
4.0
20
64
91
.V-' 111
136
• 164
240 ' 240 239
'. 350
■ 429
10V
1.6 2.0 2.5
2.6 3.0 5.0
4.0 10 10 . 15
20 20 25
24 24
29 29 35
64
91 91
r i
136
136
164 134 201
20 1 246
240 289 350
259 353
350 429 429 425 535 606 573 5 G2 495 495
Maximum Allowable Leakage (in Microamps)
15V
1,0
1.0
1.0
1,0
1.0
1,5 2.0 2.6 2.5
15
15 20
20
20
20 20
29
.' 41
35
43
64
78
76
93
' M
-36 166 192 214 254 303
294
605
25V 35V 50V
20V
1,0 1.0 1.0
1.4
1.0
1.0 1,8 1.2 2.0 5.2 7.3
1.5 2.2 2.0 3,0
2.5
3.0
3.0 4.0
7.0 5.0
4.0
9.5 10 10 12
■ 15 10 11 15 15 16 20 15 17 20 20- 19 21 23 26 31 28 32 38 34
46
49 55 65
61 68
73 82
90
W
’.G7
120 1- 12 170
144 171 204
129 157 175
1.0 2.0
3.0 6.5
5.0
17 21 25
25 30
45 54
38
54
80 96
97
■ 19 142
2C 7
100 V 20 0V 300V
1.0 3.5 4.9 6.1 4,3
6.4
3.5
7.6 11 13
9. 1 13
7.8
9.6
65 78
11 | -16 14 19 23
. 16 23
14
20 28
17
24 34 29 35 49 43 61
37
52
45
54 90 1 1C 127 76 91
111 133 192 154 23 2
r e
2C1 28 4 24 C 339 239
247
35 C 42S
■73
307 367
449
537
763 1107 959
11 CO
513 635 753 1073
1356 157C
252 25C
31S 375 450
284 339
455 540 645 913 1291
408
553 655
495
734 78 3 S71
■- 734
; ^ 1565
400V
7.4
6.1
9.0 10
9.0
11 13
16 18 19 22 25
28 33 35 40 42 48
41 50 58
61 70 74 86
73 90
500 V
7.0 7.8 '9.6 11 14
8.6
' 12 13 16
15 17
.27
104
;: i16
14
20
30 37 45 54 65
78
96
-,-;■ 127
600V 1000V
8.6
16 20 19 24 22 27 33 43 40 52 49 64 59 76 71 91 86 111
105 136
■v. 164
142 156 201
107 131 152 170. 1 8 6 24 0
;;V - 224
■29 158 183 '57
' 19 2 221
' '235
284
.348
416 480 500
408
606-
435
742
605
£99
839 11C1
:2'4 ' 1518 15 S" 19-7 234 3
1917
271 0 3130
2210
271 328 402
577 700 • 783
857 •. 959 1038 1272 1422
1825
2214 2475 J27--1 3031 3320
204
V 247 : r- ” ; 303
367
271 350 332 429 402 519
• .450 •4 92
■ 537
■•645
583 75S
- 707
• 913
. 357 1107
1050. . . 1356
. . :1161' 1272 1642
1557
. ' 2011
1697
' 1859
' 23S 3
.•'2041. 2236
2711
■ 3500
3500
3830
; 51 91
11
29 35
289
636
2886
4287
NOTE: No i n du s t ry standa r ds a re availab l e for com p onen t val u es in th e shad ed ar eas . These valu e s h a v e b een extra pola t ed from existing standards
an d ma nufa c t urer s da t a . All values not sh aded ar e based on existing EIA ind u st r y st anda r ds.
Table 4 — Maximum allowable leakage for solid tantalum electrolytics per EIA sta ndards.
Measuring Capacitor Leakage (In Ohms)
Yet, as far as the circuit is concerned, the DC loading is the same.
The LC77 uses a regulated DC power supply to provide
At times it is useful to know the amount of capacitor leakage in terms of resistance. For example, it is often easier to visualize what effect a 1 Megohm resistor will have on a high impedance circuit than it is to translate to effect of a capacitor having 1 microamp of leakage.
voltages for checking capacitor leakage. Because a DC voltage is used, the leakage currents can easily be con verted to a resistance. Placing the front panel LEAK AGE switch in the “Ohms” position allows the LC77 to display leakage current in ohms.
24
To measure capacitor leakage in ohms:
1. Connect the capacitor to the test leads. If the
capacitor is polarized, connect the red test clip to the
“ + ” capacitor terminal and the black test clip to the
terminal.
2. Set the LEAKAGE switch to the “Ohms” position to
read the leakage current in ohms.
3. Enter the normal working voltage of the capacitor as explained earlier in the section “Entering Compo
nent Parameters” on page 16.
•WARNING-
The LC77 is designed to be operated by a tech nically trained person who understands the shock hazard of up to 1000 volts applied to the test leads during the capacitor leakage test. DO NOT hold the capacitor in your hand, or touch the test leads or capacitor leads when making the capacitor leakage test.
4. Depress the CAPACITOR LEAKAGE button and read the amount of leakage resistance in the LCD dis play.
8 ■
PF
+ %/
MH
‘J u
■-%
mH
COM P O N E N T T YPE
*
in i£S :
_
| vOuts 8
©
«
f*
1
2
S
6
0
. 9
•1 '1
' I
4
CLft
•
m
CfflAWlC
CAPS COU.fe
Fig, 17 — Piace the LEAKAGE switch in the “ohm” position to measure leakage resistance.
Measuring Capacitor ESR
Fig. 18— Depress the ESR button and r ead the amount
of ESR in the LCD display.
To measure capacitor ESR:
1. Zero the test leads, as explained on page 16.
V
2. Connect the capacitor to the test leads. If the capacitor is polarized, be sure to connect the black test clip to the terminal of the capacitor and the red test clip to the “ ~r ” capacitor terminal.
3. Depress the CAPACITOR ESR button and read the amount of ESR in ohms on the digital display.
4. Compare the measured ESR to the value listed in the following ESR tables for the capacitor type, value,
and voltage rating of the capacitor you are testing.
NO TE: By e ntering the com ponent type, wor king vol
tage, and val ue parameters for the capacitor, the LC77 will automatically display the measu red ESR al ong with the same goodlbad indication as the ESR tab l es.
Equivalent Series Resistance (ESR) occurs when a capacitor develops abnormally high internal resistance. The LC 77 tests capacitors for abnormal amounts of in ternal resistance using a patent pending ESR test.
To test a capacitor for excessive ESR, simply press the CAPACITOR ESR button and compare the measured ESR to the maximum allowable ESR listed in Table 5 for aluminum electrolytic capacitors, and Table 6 for tantalum capacitors. A fully automatic good/bad test may also be used to test capacitors for excessive ESR. This test is explained in a later section of this manual.
25
Maximum Allowable ESR (in Ohms)
Standard Aluminum Electrolytic Capacitors
CAPA CITY
in u F 1.5V 3.0V 6.0V j 10 V
1.0
663 653
U Z
1.5
2.2 332 302 302 J 302 2H
3.3 201 ! 23'1 201 1 201
4.7
6.8 98 j SS 98 | 96
10 15 22 30 * 30 30 j 30 21 21 33 20 20 20 j 20 47 68
100 6.63 6.63 6.63 6.63 150 4.42 4.42 4.42 4.42 3.10 3.10 220 330 470 680 .976 .976 .976
1000 .663 .663 .663
1500 2200 3300 4700 680C
10000 .066 .066 15000
22000 .030 j .030 33000 47000 .014 .014 .0 ^ 56000 { .012 . . -.012 68C00 ] .010 ’ .010 010 .010
i42
14 1 j 14‘
66 i - 65
U
j 44
14
9.76 9.76
3.02 3.02
. 2.01 2.01
1:41
.
1- 4 1
.442 .442 .302' .302
m
*
.098 .098
.020 .020 020
c
3
663 663 442 | 442 | 310 310 | 310 | 221
141 j 141 99 99
66 1 66 46 46 46 I 33
44 j 44
'A
14 j 14 9.88 9.88
9.76 9.76 6.83 6.83
3.02 3,02 2. 11 2.11 | 2.1 1 ] 1.51
2.01 2.01
1.41 1.41 .988 [ .986 j .988 1 .706
.442 ,442 j .310
.302 .302 | .211 j .211 [ .211
.201
p i
.141 .141 .099 1 .099 .099 .098 .098 .06 3 .0 6fc .066 .066 .045 .0*8
.044 .
C30
.01 2 .0-2
15 V | 20V 25V | 35V
464 ! 464
141 141
68
31 31
14 14
4.64 4.64 4.64 | 3.32 3.32 2.65
1.41 | 1.41 j 1. 41 j 1.01
.976 .683 [ .683 { .683
.464 1 .464 ! ,464 .332
.663
j
.201 j .141 | .141 ,141
.0 31 .02’
.030 .C20 .0-4
.CM
.0-0
464
j
464 332 332 265
211 | 211
68
.310 | .310
.03-
C2-. C“4 .014
.010
j
151 151
141
j
101 101 80 80 80 99 j 71 68
j
49
31 j 22 21
j
14 ; 10
9.08 | 7.06 6,83 I 4.68
3.10 ! 2.21
.488 .488 | .390 .390 .390
.221 .221 .151 .15'
.1 01 .07 1 .07'
.C SS .049 .C-iS .035
.043 .033 .033 .03 1 .02^
.022
.015
.010
O'C
i ■
50 V 100 V 200 V 300V
265 265
177 177 177
221
121 121 12 1 121'
71 56 49 39 33 27 27 22
18 18
15 12 12 12
15
10 8.04 8.04 8.04
7.06 5,65 5.65 5.65
4.88
3.90 3.90 3.90
2.65 2.65 2.65
1.77
2.21 1,51 1.21 | 1.21
1.01 | .804 j .804 .706 | .565 .565 .565
.332 j .265 .265 .£•35 • .265 .265
.1 01 .03 0 .080 .030
.022 .CI S .010
..........................
.1.77
.177
.177 .121
■ .121
.056
.056
.C3S .027 .C27 .027 .016
.018
C 12
012
i
..................-.........
56 56 56 56
56 39 39
27
18 18 18 18 18
1.77 1.77 1.77 1.77 1,2.1
,804 | .804 .804
.17 7 .177 .177 .177
• - . .• .121
.05 6 .056 .03 9 ■■ ...039 .039 .039
.018
■012
400V 500V 600 V
265 265 265
177
8.04 8.04 8.04 8.04
5.65 5.65 5.65 5.65
3.90 3.90 3.90 3.90
1.21 1 . 21
.565 .390 .390
.121 .080 .030 .080 ;; r .080
.C 27 .018 .012
177 177 177 121 121 121
80 80 80 80
39 3S 27 27
12 12
2.65 2.65 2.65
• .565 .565 .565
■ -121
.056 .056
• .027, : . : : .027
.018 .012
39
27
12
. 1.21
.804
.350 .390
. .265.
.121
.018 .012
/ 121
1000V
1.77
.265
.177
'
.121
• ; .056
.039 .027 .01 8 .012
56
39
27
12
'
NOTE: N o industry standards are available for component values in the shaded area. These values have been extrapolated from existing standards
and manufacturers data. AH values not shaded are based on existing EIA industry st and ard s.
Table 5 — Maximum allowable ESR for aluminum electrolytics per EIA standards.
Capacitor Automatic
Good/Bad Testing
microprocessor memory. The tables and formulas in the “Auto-Z” memory are the same as those printed in this
manual, and are based on EIA standards and manufac The LC77 “Auto-Z” can automatically display a “good/ bad” indication for capacitor parameter tests. The au
tomatic tests are much faster than manual parameter tests, since you do not have to look up the result in a chart, or interpolate between listed values. The LC77 compares the measured values of dielectric absorption, leakage, and ESR to tables and formulas stored in its
turers' data. Not every parameter for some capacitor
types are specified by EIA standards or manufacturers’
data. The LC77 will not produce a “good/bad” display
for capacitor parameters not covered by industry ac
cepted standards. The capacitor types and parameters
which will produce a “good/bad” indication are listed
in Table 7.
26
Maximum Allowable ESR (in Ohms)
Dipped Solid Tantalum Capacitors
CAPACITY
in uF
1.5V
3,0V 6.0V
133
1.0
88.4
1.5
2.2
60.3 60.3 60.3 36.2 36,2
3.3
40.2
4.7
28.2 28.2
6.8
19.5 -19. 5 19.5 11.7 11.7
10
13.3 13.3 13.3 7,96 7.96
8.84
IS
22
6.03 6.03 6.03 3.62 3.62
4.02
33 47
2,82 2.82 2,82
68
1.95
100
1.33 1.3 3 .
150
0.88 0.86 0,88 0.88 220 0.60 0.60 0.60 330
0.40 0.40 0.40 0.40 0.40 470
0.28 0,28 0.28 0.28 680
0.20 0,20 0.20 0.20
1000
0.13 0.13
1500
0.09 0.09
2200
0.06
0.04
3300 4700
0.03
6800
0.02 0.02 0.02 0.02 0.02
133 133 79.6 79.6
88.4 88.4
40.2 40.2 24.1 24.1
28.2 16.9
8.84 8.84
4,02
4.02
1.95 1,95
1.33 -
0.13
0.09 0.05 0.09
0.06 0.06 0.06
0.04 0.04 0.04 0.04
0.03 0,03
10V 15V 20V 25V
53.1 53,1
5.31 5.31
2,41
1.69 1,17 1.17
0.80 0.80
0.60
0.13
0.03
— y— ■- -~-
l
35V
79.6
53.1
36.2 36.2 30.1
24.1
16.9 16.9 16.9
11.7 11.7 11.7 11.7
7.96 7.96 7.96
5.31 5.31 5.31 5.31 . 5.31. v* 5.31 j 5.31 '. ■ 5.31' /.
3.62 3.62 2,41
2.41
1.69 1 .69 1.69
1.69
1.17
0.80 0.80 0,88 0,88 0.53
G.88
0.60
0.60
0.40
0.26 0.28
0.28
0.20 0.20 0.20
0.13 0.13
0.09 0.09
0.06 0.06 0.06 0.04
0.04
0.03 0.03 0.03
0.02 0.02
66.3
79.6
53.1 44.2
24. 1
20.1 14,1 14.1 i
3.62
2.41
2.41
1.17 1.17 ■••!
1.17
0.80
0.60
0,36 :;.3C : -■ a36-'-: j'VM fe.:'.
0,40 0.24
0.17 0.17 . " .c: i7” .]. - 0:if7-:.
0;12
0.06
0.13
0.05 0,05 0.05, 0;05>
0.04
0.02 0,02
.0.01 : ■ Q-0-!: ■
0.01
100 V | 20QV
50V
66.3 .-65.3 ’ i . 6S.3 . • 66.3' | -. 66.3 ' 56.3 -.66,3 j 56.3 .'44-.2; j' 44.2 '44.2' -I'.- 44;2- ■
44.2
30.1 - p 30:i 30.?.. f 3G.1- ..j ■ 30:s-- j ' 30.1-!' ‘
30.1
'2 0 1 .' j; '20,V'.“ 2 0.l' j 20.5. -j ■ 2 D .T y j 20.1
20.1
7.Si 796 j 7.55 .
3 62 3.S2 '
2.41 ‘“V iV ■
\c = I . 1.6 9.. } ■ .-1.S9' '■ •' 1 59-.. j 1.69
3.62 ; 3.52 ; 3.52.
2.41 ■
' p 7
0.80 0.80 •' '■ ■ MD ■ 5-80:^;!... 0.S0
e.=:; ■ 0.53 !; p s f >'i0,5*7>
r..~. ' . 0.24-V
0.12
0.0s !.--a:os.
C L'.; ! !& pf
■jc :; j- c.0&:/;. ^ 0 0 2 ; .0.02 ."'!
.[■'
oo& :
q:p i;
’ .ffiOi
400V
300V
; .1 ^ . - |-„v«-.1 ■ ) : 14.2 R f
71.7 ■ | 11,7 J 11.7 ■■■
■ .7.96." 7,96..
7S5
. . 2.41 1 . -2.V41- ' ;
■.
■ Vi?.5 -...; S 1.17
3,35 v ■ i' ■ .036./; ■
.. o !if !!j .0:12^ !!
•;s.3 8. ^ e . 6 8
!;■ Q.B4 k";
;> p ;6^vl :! !sf e p2^
.o!fi2!':'j- ^ i l 2 >'.
.! ='
5Q0V | S00V
■■■ 442 . j ■■ 44.2 '- [-..±4.2 i
.' s . 3 r ; '
3.62:.' 3.62 ■
■2.41 ■■■■'. ■
1.69'" - 1.59
.. ''0:80 ^;;:
.>d!pB>;-
■ 0.01; .'.
■ 11.-7. --
7.S6 "
3.31. !;,!
■2.4v;;.. 241
'•'■1:17-. •’
. !.4S 3 ::'
w Ql36.:;.'
;;>!o:17 S '
■ -0.0& . ,0.0,5 ..>:
Y
C.01'--
j
1000V
. .-30.1
20.1 ;
f ' -
' \ \ T
. 796
;. 531 !
- 36 2
■ . 1.69 1,17 -
■ C80
; 053: '-
':p .36,;:
" ! ' P #
0.03 e,05;:;
:v 0.04^!
■ ■■■- -0.0.1 • ' •
1
NOTE: No industry standards are available for component values in the shaded areas. These values have been extrapolated from existing standards and manufacturers data. Ail values are based on existing EIA industry standards.
Table 6 — Maximum allowable ESR for dipped solid tantaium electrolytics per EIA standards.
27
CAPACITOR TYPE
TESTS TO PERFORM
Value Leakage D/A ESR Aluminum Lytic Double Layer Lytic
Tantalum
Ceramic All other caps
X
X
X
X
X
X X X
X
X
X
X
X X
(paper, film, mylar, etc.)
Table 7 — The LC77 will provide an automatic good/bad test of the capacitor parameters sh own here.
To perform an automatic good/bad test, you must enter the capacitor type, capacitance value, and voltage rat ing of the capacitor to be tested so the LC77 can deter mine the good/bad limits. If you desire to grade capacitors according to value, you must also enter the desired “ + ” and value tolerances. The value toler ances, however, do not need to be entered for automatic good/bad tests of leakage, ESR, or dielectric absorption.
TEST
Cap. Value X Cap. Leakage X Cap. ESR Cap. D/A
CAP
VALUE
X X
+ % ;
-% CAP
VOLTAGE
X X X X X X
COMPON.
TYPE
X
NOTE: The leakage test function may requir e from 4 to
8 di splay updates for the leaka ge value to settl e before a good/bad indication is di sp la yed.
X
Table 8 — These parameters must be enter ed into the
“Auto-Z” fora complete good/bad test of a capacitor.
To perform an automatic good/bad capacitor test:
1. Zero the test leads.
2. Connect the capacitor to the test leads.
3. Place the LEAKAGE switch in the “Current” posi tion. The LC77 will not give a good/bad reading with the switch in the “Ohms” position.
4. Enter the component type, value, and voltage rating of the capacitor to be tested. (Refer to the section “En tering Component Data” on page 17.)
5. To grade capacitors according to value, enter the “ + ” and value tolerance.
6..Push the desired capacitor TEST button.
7. Read the test result in the LCD along with the good/ bad indication.
Fig . 20 — The LC77 provides an automatic good/bad indic ation of each capacitor parameter.
8. The display m ust show a “good” reading for all of the tests listed in table 7 under the type of capacitor being tested.
28
Inductor Testing
Fig. 21 — Controls used for inductor testing.
The LC77 “Auto-Z'" measures the true inductance of coils using a fast, reliable patented test. Coils from
.luH to 19.99 H are automatically measured for value by connecting the test leads and pressing the test but
ton. A patented Ringer test dynamically checks the “Q”
of the coil and provides a proven good/bad check.
Balancing Out Lead Inductance
The LC77 test leads have a small amount of inductance which must be balanced out for greater accuracy when measuring inductor values smaller than 1000 uH, This lead inductance is balanced out with the LEAD ZERO switch.
To balance out test lead inductance:
1. Connect the test leads to the TEST LEAD INPUT JACK on the LC77.
2. Connect the red and black test clips together.
3. Move the LEAD ZERO switch to the “Short” position, and release when a begins to move through the display.
4. The test lead inductance will automatically be ba lanced out for all subsequent inductance tests as long as the “Auto-Z” remains on.
Fig. 22 — Connect the test leads together and push
the LEAD ZERO button to “Short” to balance out the
test lead impedence when checking small value induc tors.
NOTE: Z eroing or not zeroing t he test lead s will not affect t he Ringer test.
Inductor Value Testing
lower the Q of the coil, causing the LC77 display to read “BAD” and show less than ten ring’s.
Inductors are tested for value with the LC77 by simply
connecting the inductor to the test leads and pushing
the INDUCTOR VALUE button. No component type
switches need to be selected to measure inductance value. Make sure none of the beige capacitor type but tons are selected, or the LC77 will only display “Error
1” when the inductor test button is pressed.
NOTE: On ly the blue co l or codedLC77 bu ttons are us ed for i nduct or value testing .
To m easure inductance value:
1. Zero the test leads.
2. Connect the inductor to the test leads.
3. Push the INDUCTOR VALUE button.
4. Read the inductance value on the LCD display.
NO TE: The LC77 display will read “OP EN” if the com
ponent conn ected to the test leads has more than 20
kilohms of resista nce when the INDUCT OR VALUE button is pressed. Check the co nnections to the inductor. If you are testing a multitap coil or transformer, be sure
yo u are connected to the proper taps. If the connection s
are good, the inductor ha s an open wi nd ing and is bad.
In addition to air core coils and RF chokes, vertical deflection yokes, horizontal flyback transformers and
switching power supply transformers are reliably checked with the Ringer test. The LC77 automatically
matches the coil impedance to the necessary testing
parameters for the inductor type when the proper induc
tor COMPONENT TYPE switch is selected. Simply
select the component type and press the INDUCTOR RINGER test button to obtain the good/bad indication. Refer to the Applications section of this manual for more details on inductor types.
t v ,'-:;
COILS
, |Q r
bp mb.
1°
1 YOKES & SWITCHING 1 FLY BACK S XFORMERS
'o
u
L B m 21
: 5 I. a ll OTi- .rr,;; >
i ,PS | I CAP., i
'C <rtli 'Srti
I
o
Inductor Automatic Good/Bad Testing
The LC77 provides two good/bad tests for inductors. The first good/bad test is the patented Ringing test which checks for shorted turns (low Q) in the inductor.
The second LC77 good/bad test compares the actual measured value of an inductor to a user-entered value and tolerances. Both tests will display a good/bad read out along with the measured parameter.
NO TE: The blue color co ded TEST and COMPONENT TY PE Select bu ttons are used for inductor go odlbad tests.
Checking Inductors
With The Ringer Test
A shorted turn in many coils will go unnoticed with a value test, since the shorted turn changes the induc tance value only a small amount. The patented Ringer test, however, provides a fast and accurate good/bad indication of non-iron core coils larger than 10 uH by checking their quality or “Q” factor. The Ringer test is sensitive enough to detect even a single shorted turn
on a coil. The “Auto-Z” measures Q by applying a pulse to the coil and counting the number of ringing cycles until the ringing dampens to a preset level. A good coil will indicate “GOOD”, and 10 or more rings will be shown in the LC77 LCD display. A shorted turn will
111
Fig. 23 The inductor COMPONENT TYPE switches match the Ringer test circuits to the inductor impe dance.
FUSE
To perform the Ringer test:
1. Connect the coil to the LC77 test leads.
2. Select the proper inductor COMPONENT TYPF switch.
3. Push the INDUCTOR RINGER button.
4. Read the condition of the coil as “GOOD” or “BAD” in the LC77 LCD display.
Sp ecial Notes On Using Th e R inging T est:
1. Do no t ring c oils and transform ers hav ing lamin ated, iro n cores, such as pow er transforme rs, filt er chokes and
audio outp ut transformers . The iron core will abs o rb
the ringing ener gy and p roduce unreliable t est resul ts.
2. Good coils b elow 10 uH may not read “GOOD ” because the small i nduc tance value may not allow th e coil to rin g. Compare the nu mber o f ring s to a known good coil.
The patented S enco re Ringing test is bas ed on th e Q of the coil. Howe ver, the readin gs on the “A uto-Z” may not agree with the Q readings obt ain ed using a “Q Mete r” or bridg e . This is becaus e the Ringin g tes t h as been simp lified to provide a simple goo d/bad test, rather th an a frequency d ependent reactan ce!resistan ce ratio.
Testing Inductor Values Using The Good/Bad Test
The LC77 will automatically compare the measured value of an inductor to its marked value and display a good or bad result, based on the component being in or out of tolerance. In order for the “Auto-Z” to compare the marked value to the measured value you must prog ram the inductance value and tolerance into the LC77 using the NUMERIC KEYPAD. Then when you push the INDUCTOR VALUE button, the measured induc tance value will be displayed along with a good/bad reading based on the programmed tolerance.
IEE E 488
BU S OPE RA T IO N
All of the LC77 “Auto-Z” tests may be totally automated or incorporated into an automated test system through the use of the IEEE 488 General Purpose Interface Bus (GPIB). The LC77 is interfaced to any IEEE system or controller using the (optional) IB72 IEEE 488 Bus In terface accessory. The IB72 makes the “Auto-Z” a fully compatible IEEE instrument.
As an IEEE compatible instrument, the LC77 may have either of two functions. As a “listener” it can receive instructions from the IEEE 488 bus controller to change functions or ranges. The LC77 listener functions pro vide complete automation, as the controller is able to send any values or tolerances needed for good/bad test ing comparisons and the controller can select any of the “Auto-Z” test functions.
As a “talker” the LC77 can send readings back to the IEEE 488 bus controller as the controller requests them.
Fig. 24 — The LC77 wili provide a good/had test of inductance vaiue if the marked value and tolerance is
programmed in.
To Use The Good/Bad Inductance Test:
1. Zero the test leads.
2. Connect the inductor to the test leads.
3. Enter the marked value, along with the “ + ” and
tolerance of the inductor to be tested. (Refer to' the
section “Entering Component Data” on page 17.)
Connecting The LC77
For IEEE Operation
The IB72 IEEE 488 Bus Interface accessory must be connected to the LC77 “Auto-Z” for IEEE operation. The IB72 acts as a translator between the GPIB signals
and the microprocessor inside the LC77 “Auto-Z”. The IB72 connects to the INTERFACE ACCESSORY JACK located on the back of the LC77. The standard GPIB
cable then connects to the IB72.
4. Push the INDUCTOR VALUE button.
5. If the measured inductance value is within the prog rammed value tolerance the “GOOD” annunciator will come on.
6. If the measured inductance value is outside the prog rammed value tolerance, the “BAD” annunciator will come on.
Fig. 25 - The IB72 IEEE 488 Bus Accessory interfaces
the LC77 to any GPIB system for automated operation.
31
When using the LC77 in a Bus system only operate the LC77 from its PA251 AC Adapter/Charger. The PA251 AC Adapter/Charger prevents the auto-off circuits from removing power from the LC77 during an automated test. If the auto-off circuits shut the “Auto-Z” down, the bus controller may become hung up in the middle of its program.
Each instrument in an automated bus system must be assigned its own address in order for the controller to send instructions to or receive readings from one instru ment at a time. The address of the LC77 is set with a group of m iniature slide switches on the back of the IB72. Refer to the IB72 instruction manual for details about addresses and setting these switches.
Sp ecial Note On IEEE Programs
The computer p rograms or softwar e used to automa te a sy stem must be written for the sp ecific application being performed. Th e amount of programming required de
pends on the type of IEEE 488 c ontroller used and what
you wa nt the automation to accomplish. Most IEEE 488
progra mming is d one in the BASIC computer lan guage,
although any other l anguage compatible with y our con trol ler can be used as we ll. The exa mples covered in this section are writte n in BASIC, since it is the most c om monly used co mputer language for GPIB application s.
Sending Data To The LC77
To connect the LC77 to an automated GPIB sys
tem:
1. Remove power to the LC77 and to the IB 72.
2. Set the Bus Address slide switches on the back of
the IB72 to the address you have assigned to the LC77.
3. Connect the male DIN connector on the IB72 to the
Interface Accessory Jack on the back of the LC77.
4. Connect the AC power adapters to the LC77 and to the IB72 and connect them to AC outlets.
5. Confirm that power has reached the units by check ing the power LED on the IB72 and the digital readout on the LC77.
6. Follow the instructions for your controller to load and run the software.
As a ‘listener”, the LC77 accepts commands from the controller. These commands can be used to select a function or to send parameters to the LC77 for good/bad comparison testing. The commands sent to the “Auto-Z” during bus operation duplicate the front panel pushbut tons. Follow the same programming sequence and range limits as for manual (non-IEEE) operation.
The listener codes consist of one, two or three charac ters, and relate to the function being selected or the data being entered. Most listener codes consist only of the code characters. The listener codes used to enter data for good/bad testing consist of a number, followed by the character code.
Most controllers send information over the bus by means of a “print” statement. The information to be sent is usually placed into a variable, and the variable is then printed to the bus, along with the address of the instrument. Study the information with your con troller for details about sending information to instru ments.
The codes may be sent by the controller as either upper or lower case (capital or small) letters.
Fig. 26 - The LC77’s ad dress is selecte d by the Bus
Address switches located on the rear of the IB72.
All data sent to the LC77 must end with a linefeed character, to be recognized by the LC77. Some control lers automatically add this character to the end of every string of data, while others have a special function which adds the linefeed when activated with a software command. If your controller has neither of these op tions, you can add a linefeed character by storing the character in a variable and then adding this variable to your data before sending it to the bus.
Fig. 27 shows how the linefeed character can be stored in a string-variable called “LF$”. This variable can then be combined with the function stored in “LIS- TEN$” before being sent to the bus.
32
100 LF$*CHR$(I0 ): REN CHR$(10> IS A LINEFEED
Value Multipliers:
110 LISTEN $=LISTEN$+IF$: REM ADDS THE LINEFEED TO THE DATA 120 PRINT L ISTEN?: REM SENDS THE STRING TO THE BUS
Fig. 27 - Use th is routine to add a linefeed c haracter to the end o f data statements sent to the LC77.
The data or listener codes sent to the LC77 fall into four groups: 1. Component Type Commands, 2. Value Multipliers, 3. T est Function Commands,
and 4. G eneral Com mands. All listener codes are
listed in Table 9. They are also listed in section 12 of the Simplified Operating Instructions on the pull-chart under the unit for ready reference.
Component Type Commands
Aluminum Lytics ALM Double Layer Lytics DBL
Tantalum C a ps TAN
Ceramic Caps CER
All Other Caps AOC
Spare SPR Coils COL Yokes & Flybacks YFB Switching Transformers SWX
Value Multipliers:
(to be preceeded by numeric value) pF,uF, F, UH, MH, H ,+%, — %,V
Test Function Commands
Capacitor Val ue CAP Capacitor Le akage (current) LKI Capacitor Le a kage (ohms) LKR
Dielectric Absorption D/A
Capacitor ESR ESR
inductor Value iND Inductor Ringer R1N
General Commands
Lead Zero Open LDO Lead Zero Short LDS No Function NFC Control Panel On CPO
These GPIB listener codes let the controller send com ponent data information to the LC77 including the ideal component value and value tolerance limits. The codes duplicate the non-IEEE operation of the component parameters keypad for entering component data.
COMPON E N T PA RA M ETERS
NUMtRiC: WPOI ENfER JRFCALi
PF
CLR
/uH
mH
J :t A VS. 7 C D r\
Fig . 28 - During IEEE operation the Value Multiplier Codes allow component data to be entered into the LC77.
As with manual operation each Value Multiplier Com mand includes a number, followed by the listener code. There are four types of Value Multipliers for IEEE programming: 1. Capacitor value, 2. Inductor Values,
3. Percent tolerance, and 4. Capacitor voltage. The first three are only used for LC77 automatic good/bad com parisons. The capacitor voltage code also sets the LC77 power supply to the selected voltage for the leakage test.
When sending a component value to the LC77 it is not necessary to send long strings of zeros to establish de cimal readings. Instead, use the value multipliers uF
(microfarads) pF (picofarads), and F (farads) for capacitors and uH (microhenries), mH (millihenries),
and H (henries). For inductors the characters may be sent in upper or lower case. For example, “uF”. “UF”, or even “Uf” will all produce the same results. The
LC77 also ignores any blank spaces between listener
code characters. This means that “10UF”, “10 UF” and
even “10 U F” work equally well.
Table 9 - IEEE control codes for t he LC77.
Component Type Commands:
These codes duplicate the front panel COMPONENT TYPE switches and must be sent to the LC77 if you want the test results to be compared to the tables and
calculations associated with the LC77 microprocessor. As in non-IEEE operation, the LC77 uses these to estab lish the good/bad limits for the leakage, ESR, dielectric absorption, and coil ringing tests. The good/bad results may be in error if the wrong Component Type Command
is sent.
Note: The LED’s on the COMPONE NT TYPE switch
w hic h indicate if the sw itch i s selec t ed DO NOT li ght
whe n the L C7 7 is und er I EEE contro l.
The complete Value Multiplier code consists of the cor rect numeric value, the Value Multiplier, and the End Terminator. The following examples show valid com mands, with the End Terminators not shown:
33
4.7 uF
(enters capacitor value of 4.7 microfarad)
100 pF
(enters capcacitor value of 100 picofarads)
15 V
(enters leakage voltage of 15 volts) 20 + %
(enters value tolerance of -t- 20%)
5H
(enters inductance value of 5 Henrys)
Setting The Leakage Voltage:
The leakage power supply must be set to the desired voltage before selecting a leakage test with the LKI or the LKR codes. The supply can be set to the nearest tenth of a volt. The listener code simply consists of the
desired voltage followed by the letter V and the End Terminator. For example, “100V” sets the supply to produce 100 volts when a leakage function is activated.
The highest voltage which can be programmed into the LC77 is 999.9 volts the lowest is 1 volt. Attempting to
enter a voltage higher or lower than this range will produce an “Error 2” condition.
The amount of component data which needs to be en tered with the IEEE Value Multiplier codes for a good/ bad test depends on the LC77 function. The chart in Table 10 shows the component parameters needed for each good/bad test. Sending additional data to the LC77
will not affect the tests.
TEST
Cap. Value X Cap. Leaka g e Cap. E SR Cap. D/A
Ind. Value Ind. Ringing
CAP
VALUE
X X X
IND -f% -% CAP
VALUE VOLTAGE
*
*
X X
X
* *
X
COMPON.
TYPE
X X X X X X
X = Must be entered for good/bad results.
*= Tolerances are set to zero percent at power-up.
Table 10 - These para meters must be entered for the
LC7 7 to produce a good /bad te st result.
NO TE: The LC77 wil l send go od/bad indicators back to the cont roller for each reading if al l necessary i nfor mation has been supplied. To stop the LC77 from send ing the “G” or the “B” as pa rt of its returned data, simply send a zero value reading, s uch as “0pF“. Th e other V alue Multipliers (such as percentage s or volt age) will remain in the L C77 memory u ntil changed or unt il
power is remove d from th e unit.
The plus and minus component tolerance limits must be sent in the correct form. First, the number must be a whole number, with no decimal. Then, the percen tages must be within the allowable range. The largest negative number allowed is 99 percent (-99%), and the largest positive number allowed is 100 percent (+100%).. Numbers that are outside this range, or that contain a decimal, produce an “Error 2” condition.
The leakage power supply only applies power to the
test leads after one of the two leakage functions have been selected with the LKI or LKR listener code. The power supply automatically removes voltage from the test leads when the controller sends any other listener code, or when any front-panel button is pressed.
------------------
WARNING
------------:-----
The warning LED on the front of the LC77 will flash as a reminder that a shock hazard
of up to 1000 volts may be applied to the test leads when a leakage test is selected. Use ex treme caution when the LED is blinking.
NO TE: When not u sin g a lea kag e test, send the lis tener
code “OV” to the LC77 to prevent a ccid entally applyi ng a voltage to the test lead s .
Test Function Commands:
One of the seven listener Test Function Codes must be sent to the LC77 before the controller can request a
reading. The selected function is cancelled by any other
listener code sent to the LC77, meaning that a Test Function Command must be the last listener code sent before a reading is requested.
The LC 77 will remain in the last function selected until
it receives another test function command or listener
code. The controller can select an LC77 test, go on to
other instruments on the bus, and then come back to
the LC77 at a later time to request a reading. This
allows tests which require longer times, such as
capacitor leakage, to be used without slowing the oper
ation of other instruments on the bus.
34
TEST
CAPACITOR
VALUE
CAPACITORS
LEAKA GE j
functions with a Test Function Command or when
changing component parameters with a Value Multip lier Command, since any listener code clears the cur rent function. Sending the “NFC” command when the
LC77 is not in a test function has no effect.
DIELECTRIC
ABSORP
INDUCTOR 1
VALUE I
CAPACITOR
ESR
INDUCTOR
RINGER
Test Function Commands
Capacitor Value CAP Capacitor Leakage (current) LKI Capacitor Leakag e (ohms) LKR
Dielectric Absorption D/A Capacitor ESR ESR
Inductor V alue IND
Inductor Ringer RIN
Fig. 29 - The LC77 TEST functions are selected via IEEE using t he Test Function Commands.
The LC77 starts a test from its beginning every time it receives another Test Function Code. Therefore, if the LC77 has been preset to a function for a delayed reading, make certain that the controller does not re send the code just before a reading is taken.
General Codes:
The four general listener codes activate special func
tions when sent to the LC77. The codes let the controller instruct the LC77 to compensate for the test leads, clear a function, or return control of the LC77 to the front- panel switches.
The LC77 must subtract residual effects of the test leads when testing ESR, and small capacitor or inductor values. The Lead Zero (LDO) and Lead Short (LDS) listener codes duplicate the operation of the front-panel LEAD ZERO button to null out the effects of the re sidual resistance, capacitance, and inductance of the test leads and test fixture. The leads must be shorted before sending the LDS command and opened before sending the LDO command. If not, the test lead impe dance will not be compensated for.
NOTE: The leads can be nulled man ually before turnin g
control of the LC77 over to the automated system, Simply
follow th e pr oce dur es f or manually nulling the effects
of the leads, as explai ned on page 16. The LC 77 will reme mber the correc t compensation u ntil the power is
turned off.
----------------
IMPORTANT
-----------------
Do not disconnect or connect any components to the LC77 after performing any capacitor or inductor test without first sending a No Function Command (NFC) or other command first to clear the test function. The LC77 may be damaged if a charged capacitor, or static voltage is connected to it. Also, a severe shock hazard may exist to the user if a capacitor is removed after a leakage test without first being discharged.
The front-panel switches are automatically disabled whenever the LC77 receives its first GPIB command through the IB72. As a reminder of this, any LEDs
associated with the COMPONENT TYPE switches will
turn off as soon as the LC77 receives a GPIB command.
The panel will remain locked out for all functions until the Control Panel On (CPO) code is sent or until power
to the LC77 is removed.
NOTE: One exce p tion is the capacitor leakag e function. Depressi ng any. of the fron t-panel switches will unlatch
the le akage pow er supply.
Reading Data From The LC77
The LC77 will send data to the controller through the
IB72 IEEE 488 Bus Interface accessory whenever the
controller sends the correct talker address and a “Talk”
command. The data returned over the bus will be the
same as the reading appearing in the LCD display.
Error messages will also be returned over the bus. The
error codes will be the same as the codes during manual
(non-bus) operation, and are listed on page 37.
NOTE: Most controllers automaticall y co mbine the
“Talk” com mand with the instruct ion containing the
add ress, so there is not a s eparate step required in the pro gr am. Con sult the. manual for the c ont roller you are
u sing for informatio n on its oper ation.
Once addressed, the LC77 sends a reading over the bus
every time it updates the reading on the LCD display.
The softwear in the controller determines how many
readings are recorded. Some applications only need a
single reading, while other applications may require
collecting several readings in a row,
The No Function Command (NFC) cancels any test that
is in progress and places the LC77 into the standby
.node (no button pressed.) You only need to send “NFC”
f you want to clear a test. For example, you may wish
o turn off the capacitor value test function while you remove one component and replace it with a different one. It is not necessary to send “NFC” when changing
The only difference between collecting a single reading or collecting a series of readings is in the controller software. If only one reading is desired, the controller will trigger the talker function, and then w ait until one reading is received. Then the controller sends a bus instruction which causes the LC77 to stop sending read ings.
35
One way to stop the LC 77 from sending readings is to
simply address a different instrument on the bus with the controller. The LC77 will remain in the test func tion, but the readings will not be sent to the controller until the LC77’s talk address is again selected by the controller.
A second method to stop the LC77 from sending read ings is to send any listener code, including the No Func tion Code (NFC), to the LC77. This will both stop the readings and place the LC77 into its standby mode. Always use this method if a different component is going to be connected to the LC77.
NOTE : Th eLC77 will retu rn a C ontr ol Pan el O n(CPO)
he ader if it is addre ssed to talk but has not re ceived a
valid listener code. A No Functio n Command (NFC) is re t urned if the LC 77 has rece ived a va lid li sten er code, but has not been given a T est Function Command .
Numerical Data Field: The 11 spaces following the Header (characters 4 through 14) contain the numerical results of a talker function. The values returned from
a test function are in scientific notation, allowing any value to be represented with the same number of characters. Error codes appear as a single digit (from
1 to 7) without the scientific notation.
N OTE: The L C77 does not need (nor does it respond to) the special “GET” (group-execute-trigger) command
used in some contr olle rs. It w ill begin sending resul t s
as soon as the talk command is complete.
Data Format
All data returned from the LC77 falls into a standard data format. Each data string is 17 characters long and contains information in four data fields. The software can keep the entire string of characters together, or it can separate the data into three parts for calculations or processing.
CAPXXX • XXXEXXXG CR LF
Header Numeric Data Field I End
j Terminator
Good/Bad Indicator
Fig. 30 - The da ta form at returned by the LC77 is a
string of 17 characters long.
Good/Bad Indicator: The single space following the Numerical Data Field (the fifteenth character) is re
served for the results of the automatic LC77 good/bad tests. The single letter “G” or “B,J appears in this pos
ition when the LC77 has sufficient information to deter mine if the reading is good or bad. If a piece of data
(such as the tolerance or ideal value) is missing, the
position occupied by the Good/Bad Indicator is left
blank.
NO TE: A leakage test function may requ ire from 4 to 8
re adings for the leakage to settl e before providing a good!
bad in dicati on.
End Terminator: All data ends with both a carriage return (ASCII decimal 13) and a linefeed (ASCII deci
mal 10) character, as recommended by the IEEE 488
standard. Many controllers respond to either character,
while others only respond if the linefeed is present. A
few controllers, however, may stop accepting data when
the carriage return character is sent, leaving the LC77
hung up waiting to send its last (linefeed) character. If
this happens, you may need to put an extra GET or
INPUT statement into your program to'let the LC77
send its last character into an unused variable. Refer
to the manual for the specific controller that you are
using for information on the end terminator it acts on.
Separating Data Fields
The four fields of the data string are: 1. Header, 2. Numerical Data Field, 3. Good/Bad Indicator, and 4. End Terminator. Each field has the same number of characters for all test functions, allowing the same sub routines to process any returned data. Here are the details for each field of data.
Header: The first three characters identify the test function which produced the reading. The three charac ters sent back from the instrument are usually the same as the test function commands used to select a function when the LC77 acts as a listener. These codes let the software identify the source of the data, confirm that the correct function is producing readings, or label the data for future retrieval.
In certain cases, the Header identifies some special con ditions, such as errors or shorted or open components. The controller software should test for these conditions before processing readings for accurate test results, as explained in the section “Error Testing” on page 37.
The BASIC commands needed to separate the three
fields of information into separate variables are LEFT$
and MID$. The LEFTS command can collect the three
characters of the Header if they need to be compared
to information within the program. The MID$ com
mand is used to separate the Numerical Data Field and
the Good/Bad Indicator from the other results.
2000 REM SUBROUTINE TO SEPARATE DATA INTO 3 PARTS
2010 HEAD$* LEF T$(RES ULT $,3): REM FIND HEADER
20 20 ANSW ER=VAL(MID$(R ES U L T$ , 4 ,1 1 )): REM VALUE
20 30 G00D$=MID$(R ESULT S,15 ,1 ): REM FIND GOOD/BAD ;
20 40 RETURN: REM JUMP BACK TO MAIN PROGRAM
Fig, 31 - The formatted data returned by the LC77 car
be easily s eparated into string-var iables using simple BASIC commands.
36
For example, the controller could place a reading from the LC77 into a string-variable called RESULTS. The subroutine in Figure 31 can then separate the header into the string-variable HEAD$, the Numercial Data into the numerical-variable ANSWER, and the Good/
Bad Indicator into the string-variable GOOD$.
Line 2010 moves the first 3 characters into the header variable. Line 2020 selects the 11 characters, starting at the fourth position, and then converts the result to a value (with the VAL statement) before placing it into ANSWER. Line 2030 selects the fifteenth character and moves it to GOOD$. This subroutine can be used to separate data from any reading into the three main parts.
Most errors cause the LC77 to return a header with the three letters “ERR’'. A simple test for this header allows the program to be alerted to the error. The value of the Numerical Data Field tells the controller which of seven errors have occurred. The error codes are sum marized in Table 11. Refer to the section entitled “Error Codes” for a more detailed explanation of each error condition. The program segment listed in Figure 32 tests for errors and then prints a message which indi cates its cause.
200 GOSUB 2000: REM SEPARATE DATA INTO PARTS
Program languages other than BASIC have similar commands which can separate the data into its different fields.
Advanced Programm ing Ideas
After the data has been separated, there are many things your program can do to process it. This section
explains how to add these refinements to your BASIC programs. In each case, we will refer to the short sub routine listing in Figure 31, with a GOSUB 2000 state ment, resulting in the LC77 reading being stored in the variables HEAD$, ANSWER, and GOOD$.
Error Testing
Your controller software should test for error conditions (often called “error trapping”) after every reading has been collected from the LC77 to avoid an error from causing unexpected results. The software can either report the error or skip over it, but should do one or the other without crashing the program. If your prog ram is particularly advanced, it may test for the type of error (as indicated by the error number returned in the Numerical Data Field) and then branch to different parts of the program which can take the correct action
to compensate for the error.
210 IF HEAD$<>"ERR" THEN GOTO 300: REM NO ER ROR FOUND
220 ON ANSWER GOT O 230,240,250,260,270,280,290
230 PRINT "COMPONENT TYPE SELECTI ON ERROR"; GOTO 300
240 PR INT " VALUE BEYOND RANG E OF UNIT": GOTO 300
250 PRINT "VALUE BEYOND RAN GE OF TEST”: GOTO 300
260 PRINT "VALUE BEYOND ZEROING L IMIT": GOTO 300
270 PRINT nN0 VOLTAGE ENTERED": GOT O 300
280 PR INT “INVALID IEEE COMMAND’': GOTO 300
290 PRINT "COMPONENT OUT OF T EST RANGE" : GOTO 300
300 __(Rest of Program)
Fig, 32 - A simple BASIC subroutine allows any errors
to be identified,
Line 210 in Figure 32 causes the program to jump over the error messages for any header except “ERR”. The next line takes advantage of the ON..GOTO function of BASIC which sends the program to line number 230 if ANSWER = 1, to line 240 if ANSWER = 2, etc.
Error
Description
1 Co m p o n e n t Type selection error
2
Entered value b e yo n d r ange of unit
3
Entered value be yo n d r ange of test Value beyond zeroi ng li mit
4
N o v o lt a g e entered
5
Inv alid SE EE command
6 7
Component out of test range
Table 11 - Error codes returned by the LC77 during IEEE oper ation.
NOTE: Er rors d etected by the LC77 do not cause a ser vice request (SRQ) on th e bus. The LC 77 does n ot re spond to seri al or parallel polls because e rrors are sent as part of the nor mal data string, instead o f with a servi ce request.
Good/Bad Results
The string-variable GOOD$ in Figure 31 will contain a single ASCII character, either G or B. The contents of GOOD$ can be tested with simple IF statements and used to produce any desired output. If the Good/Bad Indicator Field is blank, the program can indicate that the result is not available because the LC77 has insuf
ficient data to make a comparison. If the field contains the letter “G” or “B”, the controller can print a message concerning the quality of the part. Figure 33 lists a BASIC subroutine which can be used to check the good/ bad test result.
37
iAO GOSU B 2000: REM SEPARATE DATA INTO PARTS
150 IF G00D$**‘ " TRE N PRINT "NO GOOD/BAD TEST”
160 IF GOOD$=,,G” THEN PRINT "THE RESULT IS GOOD”
170 IF G00D$* "B” THEN PRINT "THE RESULT IS BAD"
180 ...(Rest of Program)
Fig. 33 - Thi s subroutine can be used to read the result of the L C7 7 automatic good/ bad test
Shorted Capacitors:
The LC77 automatically senses if a capacitor is shorted
before performing a capacitor value test. If a short is detected, the LC77 sends the letters “SHT” as the Header Field of the returned data and displays “Short” in the LCD display. Adding one line of program code will test for this condition. This line should appear be
fore any part of the software program which depends
on a value reading, so that the value test will be skipped in case of a shorted capacitor. The program section
listed in Figure 34 tests for shorts, prints an error mes
sage on the CRT, and jumps to line 400, which handles the error.
200 GOSUB 2000: REM SEPAR ATE DATA INTO PARTS
210 IF HEAD$=,,SHT“ TH EN PRINT "CAP IS SHORTED": GOTO 400
220 ...(Rest of Program)...
400 . ..(Err or Handling Function s)
Fig. 34 ~ The LC77 returns a “SHT” data Header when a shorted capacitor is test ed. This sample subr outin e
checks for the short indicati on.
Making Leakage Tests With IEEE:
When testing for leakage on large capacitors, the first reading returned by the LC77 may be outside the nor mal leakage limits because the capacitor is charging. In the case of electrolytics, several readings may be needed before the capacitor drops to a “good” level, since an electrolytic also goes through a re-forming process every time it is charged from zero. This means that the controller software should ignore the first few readings in order to accept a meaningful reading.
There are several ways to handle this in the software. For example, the program could place the LC77 into the leakage function (with the “LKI” listener code) and then set a softwear timer to insert the correct delay
(based on the normal charging time of the capacitor)
before reading the leakage value. During this time, the
controller could work with other instruments on the bus to keep the delay from slowing down other steps in the automated system. Rather than a fixed time delay, the software can be written to ignore a certain number of readings before recording the one which is to be checked for value.
In either case, the controller can base its decision on whether the capacitor is good or bad by using the Good/ Bad Indicator in the returned data. For the automatic good/bad test to function the capacitor’s value, voltage, and type must be sent to the LC77 prior to the test. This allows the LC77 microprocessor to compare the leakage readings to the internal formulas and tables. The program steps listed in Figure 36 can be used to report on the capacitor’s condition. The program then
jumps to line 200 for further testing. If GOOD$ contains
neither a “G” nor a “B” then the steps from 140 to 199 take the steps needed to work with a non-good/bad test.
100 ...(Program with leaka ge delay)
Open Inductors:
The LC77 automatically senses if an inductor is open (or if the test leads are not connected to the coil) before performing an inductor value test. If an open is de tected. the LC77 sends the letters “OPN” as the header and displays “OPEN” in the LCD display. One addi tional program line will test for this condition. Place
this line before any portion of the program which de pends on an inductor value reading, so that the value test will be skipped in case of an open inductor. The program section listed in Figure 35 tests for opens,
prints an error message on the CRT, and jumps to line
300, which handles the error.
100 GOSUB 2000: REK SEPARAT E DATA INTO PARTS
110 IF HEAD$** ‘OP N” THEN PRINT "COIL IS OPEN: GOTO 300
120 ... (Rest of Program)...
300 ...(Error Handling Functions)
Fig. 35 - Open tesi leads or an o pen ind uctor cause the LC77 to return the data header “OPN ". This simple
subroutine may be used to check for an open condi
tion.
110 GOSUB 2000: REM SEPARATE DATA INTO PARTS
120 IF GOOD$-*'G‘* THEN PRINT "LEAKAGE IS OKAY": GOT O 200
130 IF GOOD$='‘B‘’ THEN PRINT " LEAKAGE IS BAD": GOTO 200
140 ...(Progr am steps for no G/B test) ...
200 ...(Rest of Program)
Fig. 36 - The good/bad indicator Fi eld Returned by the
LC77 can be checked to test capaci tor leakage.
Making ESR Tests With IEEE:
The capacitor test for Equivalent Series Resistance (ESR) may cause unexpected program errors if your software does not handle the returned data correctly. Remember that ESR tests are only valid on electrolytic capacitors with values larger than 1 microfarad. Also remember that some caspacitors may have such high levels of ESR that the value is above the measuring range of the test. Therefore, make certain that your
software tests for the following conditions:
1. An “ERR 1” occurs if any component type other than ALM, DBL, or TAN has been sent to the LC77 in its listener mode.
38
2. An “ERR 3” occurs if the capacitor under test meas ures less than. 1 microfarad.
3. An “ERR 7” occurs if the amount of ESR is above 2000 ohms.
4. The leads must be zeroed (either manually or by using the “LDS” listener function) before making ESR tests, or the added lead resistance may cause erroneous results.
Programming Examples
Line 10000 will be unique to each controller. Refer to the manual for the specific controller you are using for details on how it sends data to the IEEE bus.
The steps listed in Figure 37 send all the information needed by the LC77 to test an aluminum electrolytic capacitor with an ideal value of 50 uF, a working vol tage of 15 volts and a tolerance of + 80% and -20%. The
primary address of the LC77 is 8. Each “GOSUB 10000”
line sends the data to the unit.
It would be impossible to write a program, that would work for every LC77 user. First, there are numerous types of bus controllers. Additionally, dozens of per sonal computers (PC’s) can be converted to bus control lers by adding a GPIB control card or expansion device. Each PC could use any of several different GPIB cards. But in addition to hardware differences, the application of the LC77 will be different for each bus system. For example, a Reliability Lab will run different tests than an Incoming Inspection System will.
Several programming hints are provided in this section to help you get your LC77 bus system up and running. The first examples are “building block” programs which allow you to plug the specific details for your controller into an LC77 “Auto-Z” test program. Two complete programs are included at the end of this section. Those programs are ready to run, provided you have the same hardware for which they were written.
Sending Listener Codes
The specific steps needed to send listener codes to in
struments on the bus depend on the controller you are
using. Some controllers only require the addition of a
special code (such as a control character) into a standard
PRINT statement. Most, however, require several addi
tional initialization steps to tell the controller’s micro processor which expansion slot or memory location con tains the interface card, the address of the instrument being addressed, which method is used to address the
talkers or listeners, and so on. This doesn’t have to complicate programming, however,
if you use subroutines to take care of all these details.
You simply debug these subroutines once, and call them
each time you send information over the bus. Your
main program places a couple of pieces of information
into variables before turning control over to the sub routine which, in turn, handles all the details of com
municating with the bus.
Fig. 37 shows an example of a program which uses a
subroutine at line 10000 to send information to any
instrument on the bus. This subroutine needs two pieces
of information; the listener address of the instrument
and the data to send to it. The primary address is placed
into the variable ADDRESS, and the data into the
string-variable CODE$ before calling the subroutine.
Once ADDRESS has been loaded, it does not need to
be changed unless the controller needs to work with a
different instrument. This is the reason line 100 is the
only one which uses the variable ADDRESS.
100
110 CODE$="5Q UF’
120
130
140 GOSUB 10000
150
160 GOSUB 10000
17 0
180 GOSUB 100 00
190
200
Fig . 37 - This sa mple program uses a s ubroutine to si mplify sending data over the bus to the LC7 7. The
subrouti ne called up is unique to each controller.
ADDRESS=8 : REM PRIM AR Y ADDRESS OF LC77
REM I DEAL VALUE
GOSUB 10 000:
CODE$= " 1 5V” :
C0DE $ = “ ALM":
C0DE $ = M8 0+ %" :
CODE$=*’ 20-% ":
GOSUB 1000 0
REM SEND V ALUE TO L C 7 7
REM WORKING VOLTAGE
REM CAPACI TO R TYPE
: REM POSITI VE TOLERANCE
: REM NE GATIV E TOLERANCE
Sending Talker Codes
As with sending listener codes, all the steps needed to
transfer information from the LC77 back to the control
ler can be done in a subroutine which is called every time the program requests a reading. In the example listed in Figure 38, the subroutine is at line 12000. The listener subroutine is still at line 10000.
Some controllers require a different talker and listener address, but these addresses can be calculated by the program. The subroutine at line 10000 calculates the necessary listener address, while the subroutine at line
12000 calculates the needed talker address from the value already stored in the variable ADDRESS. Thus, it is not necessary to place a new value into the AD DRESS variable.
The last line of the subroutine starting at line 12000 includes an INPUT statement which collects the LC77 reading and places it into the string-variable RE
SULTS. RESULT$ is then processed through another
subroutine to separate the data into its three parts.
39
210 C0 DE$ «"CAP" : REM LISTENER CODE FOR CAP VALUE
220 GOSUB 100 00: REM SEND CODE TO UNIT
230 GOSUB 120 00: REM REQUEST READING FROM UNIT
240 CVALUE $=RESULT $ : REM TRANSFER FROM SUBROUTINE
250 C 0DE$*"LKI” : REM LISTENER CODE FOR LEAKAGE
260 GOSUB 1000 0: REK SEND CODE TO UNIT
270 GOSUB 12000: REK REQUEST READING FROM UNIT
280 LEAK $ =RESU LT$: REM TRANSFER FROM SUBROUTINE
290 CODE$2c"D/A " : REH CODE FOR DIEL ECTRIC ABSORB.
300 GOSUB 100 00: REM SAME AS BEFORE
310 GOSUB 12000
320 DA$“ RESULT$
330 CODE$=” ES R": REM CODE FOR ESR TEST
340 GOSUB 10 000
350 GOSUB 12000
360 ESR$*=RESULT$
Fig. 38 -A subrouti ne can b e used to simplify reading
the data sent over the bus b y the L C77. The subroutine
called is unique to each controller.
Sample Program s
The two sample programs which follow are ready to run. However, they will only work for the type of bus
controller stated in the open remark section of the prog ram. Use them as a guide for connecting the LC77 into your IEEE bus system.
1 REM THIS PRO GRAM ALLOWS THE DSER TO ENTER THE
% REM STANDARD VALUES FOR ANY CAPACITOR, SENDS THE
3 REM VALUE S TO THE LC77, AND THEN SHOWS THE RESULTS 4 REM AS GOOD OR BAD. COPY RIGHT (C) SENCORE FIELD 5 REM APPLICATION DEPA RTMENT , 1987. THIS PROGRAM MAY
6 REM MAY BE USED AS IS OR MODIFIED BY ANY LC77 OWNER
7 REM WITHOUT FURTHER PERMISI ON FROM SENCORE, ISC.
10 REM
20 D$ = CHR$ (4): REM DOS COMMAND CHARACTER
30 Z$ = CHR$ (26): REM IE EE CARD COMMAND CHARACTER 40 Q$ = CHR$ (17): REM SCREEN TO 40 COLUMNS 50 G$ = CHR$ (7): REM RINGS BELL 60 FOR X = 1 TO 19 :BL$ = BL$ + " NEXT X: REM
FOR MS 20 BLANK SPACES 70 DATA ALM,DB L,TAN,CER,AOC 80 FOR X = 1 TO 5: READ CT$(X): NEXT X
1000 REM ******* INPUT D ESIRED VALUES ******* 1010 HOME : GOSUB 10200: REM SE LECT PRIMARY ADDRESS 1020 REM ******* BEGIN IDEAL INPUT ******* 1030 HOME : VTAB 7: IN VERSE : HTAB 6: PRINT " ENTER
IDEAL VALUES: NORMAL
1040 PRINT : HTAB 6: INPUT ” VALUE: " ;V$ 1050 V = VAL (V$): REM CONVERT TO NUMERIC VALUE 1060 IF V = 0 GOTO 1020: REM ZERO VALUE NOT ACCEPTED 1070 VTA B 9: HTAB 16: PRINT V;" 1080 VTAB 11: HTAB 1: INVERSE : PRIN T "MULTIPLIER:";:
NORMAL : PR INT ” [1] PF, [2] UF, [3] F ";: GET K$
1090 MU $ * ”F":VM = 1 1100 IF K$ = “ I" THEN MU$ = "PF “:VM = IE - 12 1110 IF K$ - *,2" THEN MU$ = "UF“:VM = IE - 6
1120 IF K$ < "1" OR K$ > ”3" GOTO 1080: REM REPE AT UNTIL
VALID
1130 VTAB 10: PRINT BL$;BL$: REM COVER WITH BLANK
SPACES
1140 VTAB 9: HTAB 25: PRINT MU$: REM ECHO SELECTION TO
SCREEN
1150 V$ = STR$ (V) + M U$: REM PREPARE STRIN G TO SEND TO
METER 1160 HTAE 6: INPUT " +%: ";PP$ 1170 PP = V AL (PP$): REM REMOVE NON-NUMERIC CHARACTERS 1180 PP$ = STR$ (PP) + "+ Z ": REM PREPARE STRIN G TO SEND
TO METER 1190 HTAB 6: INPUT " -%: ";PN$ 1200 PN = VAL (PN$): REM R EMOVE NON-NUMERIC CHARACTERS 1210 PN$ = STR$ (PN) + 1220 HTAB 6: INPUT " VO LTAGE: " ;VT$
1230 VT = VAL (VT$) : REM REMOVE NON- NUMERI C CHARACTERS
1240 VT$ = STR$ (VT) + "V" 1250 PRINT ; PRINT " ARE THESE VALUES CORRECT? (Y/N)
1260 IF = "y" THEN K$ = MY" 1270 IF K$ C > "Y" TH EN 1020 1280 HOME : VTAB 7: INVERSE : HTAB 6: PRINT " SELECT
1290 PRINT 1300 HTAB 6: PR INT ”[1] ALUMINUM LYTIC"
1310 HTAB 6: PRINT "(2] DOUBLE LAYER LYTIC” 1320 HTAB 6: PRINT ”[3] TANTALUM LYTIC" 1330 HTAB 6: PRINT "f4] CERAMIC CAP"
1340 HTAB 6: PRINT "[5] ALL OTHE R CAPS" 1350 PRINT : HTAB 6: PRINT "SELECT NUMBER FOR TYPE:
1360 IF ASC (K$) < 49 OR ASC (K$) > 53 THEN PRINT
1370 TY$ = CT$( VAL (K$)): REM SELECT TH REE-LETTER
1380 VTAB 19: HTAB 6: INVERSE : PRINT'” SENDING VALUES
1390 GOSUB 10000: REM TURN ON IEEE CARD 1400 PRINT LA$;Z$;V$: P RINT LA$;Z$;PPS: PRINT
1410 REM --LA$=LISTEN ADDRESS, Z$=CONTROL-Z
1420 REM ******* BEGIN TAKING READING ******* 1430 FG = 0: REM RESET "COMPONENT BAD' FLAG 1440 GOSUB 10100: REM RETURN COMMUNICATIONS TO
1450 HOME : VTAB 14: H TAB 6: INVER SE : PRINT " TAKING
1460 GOSUB 10000: REM TU RNS ON IEEE CARD 1470 DA$ = "D/A": GOSUB 10500 1480 ZD$ = RZ$ 1490 DA? = "CAP": GOSUB 10 500 1500 ZV$ = RZ$
1510 DA$ = "LKI": GOSUB 105 00
1520 ZI$ = RZ$
1530 DA$ = "ESR": GOSUB 10500
1540 ZR$ = RZ$
1550 DA$ = "NEC": GOSUB 10500: REM CANCEL PANEL
1560 GOSUB 10100
1570 REM ******* PRINT RESUL TS *******
1580 HOME : REM CLEARS SCREEN 1590 PRINT " THE RES ULTS OF T HIS TES T ARE:": PRINT 1600 PRINT "IDEAL VALUE: ";V$
1610 RE$ = ZV$: REM LOAD VALU E INTO SUBROU TINE
1620 GOSUB 2000: REM S EPARATE DA TA INTO PARTS
1630 IF HE$ = "ERR" THEN GOSUB 2100: GOTO 1710
1640 IF HE$ = "SHT" THEN PRINT "CAPA CITOR IS SHORTED":
1650 PRINT " MEASU RED VALUE: "AN
1660 GOSUB 2200: REM GET GOOD/BAD RESULT
1670 PC = 100 * (AN - (V * VM)) / (V * VM): REM
1680 PC = INT (10 * PC) / 10: REM SET DECIMAL AT ONE
1690 PRINT " THE VALUE D IFFE RED BY "PC"%"
1700 PRINT : PRINT “THE LEAKAGE TESTED AT "VT" VOLTS”
1710 RE$.= ZI$: REM LOAD L EAKAGE INTO SUBROUTINE
1720 GO SUB 2000: REM SEPARATE DATA INTO PARTS
1730 IF HE$ = “ERR” TH EN GOSUB 2100: GOTO 1770
1740 LK = AN * 1E6
GET K$
CAPACITOR TYPE: NORMAL
GET K$: ..PRINT K$
G$;G$: GOTO 1280: REM ACCEPT ONLY 1 THROUGH 5
CODE
TO Z METER : NOR MAL
LA$;Z$;PN$: PRINT LA$;Z$;V T$: PRINT LA$;Z$;T Y$
KEYBOARD
READINGS NORMAL
VARIABLE
GOTO 1920
CALCULATE PERCENTAGE PLACE
VARIABLE
40
1750 PR INT " WAS ”LK" MICROAMPERES." 1760 GOS UB 2200: REM GET GOOD /BAD RESULTS 1770 PRINT : PR INT "D/A TEST: " 1780 RE$ = ZD$: REM LOAD D/A RESULTS INTO SUB ROUTINE
VARIABLE 1790 GOSUB 2000: REM SEPARATE DATA INTO PARTS 1800 IF HE$ = "ERR” THEN GOSUB 2100: GOTO 1840 1810 AN = INT (10 * AN) / 10: REM SET DEC IMAL TO 1
PLACE 1820 PRINT " DIELECTRI C ABSORPT ION: "AN"%." 1830 GOSUB 2200: REM GET GOOD/BAD RESULT 1840 PR INT : PRINT "ESR TEST:” 1850 RE$ = ZR$: REM LOAD ESR VALUE INTO SUBROUTINE
VA RIABLE 1860 GOSUB 2000: REM SEPARATE INTO PARTS 1870 IF HE$ = "ERR" THE N GOSUB 21 0 0 : GOTO 1900 1880 PRINT " SERIE S RESISTANCE: " AN” OHMS."
1890 GOSUB 2200: REM GET GOOD/BAD RESULTS 1900 GB$ - " GOOD "; IF FG - 1 THEN GB$ - " BAD " 1910 PRINT : PR INT "THE CAP ACIT OR IS ";: INVERSE : PRINT
GB$: NO RMAL
1920 PRINT : PRINT "END OF RESULTS, PRESS ANY KEY " ;:
GET K$
1930 H OME : VTAB 9: HTAB 6; IN VERSE : PRINT " SELECT
NEXT OPTION : ": NORMAL 1940 PRINT : HTAB 6: PRINT "[1] ENTER NEW VALUE" 1950 HTAB 6: PRINT "[2] MA KE ANOTHER TEST" 1960 HTAB 6: PRINT “[3] REPEA T PRINTOUT" 1970 PRINT : HTAB 6: P RINT "SELECT NUMBER OPTION:
GET K$ 1980 IF K$ < "1" OR K$ > "3" THEN PRINT G$: GOTO 1930 1990 ON VAL (K$) GOTO 1020,1420,1570 200 0 REM # # # # # SUBROUTINE SEPARATES DATA //##### 2010 HE$ = LEFT$ (RE$,3): REM FIND HEADER 2020 AN - VAL ( MID$ (RE$,4,11)): REM FIND NUMERIC
VA LUE 2030 GD$ * MID$ (RE$ ,15,1): REM FIND GOOD/BAD RESULT 2040 RETURN 2100 REM #######SUBROUTINE FOR ER ROR HANDLING#######
2110 PRI NT G $;"Z-METER ER ROR #”AN" DETECTED:" 2X20 ON Ab4 GOTO 2130,21 40,2150,2160,2 170,2 180,2190 2130 PRINT "COMPONENT TYPE SELECTION ERROR": RET URN 2140 PRINT " VALUE BEYOND RANGE OF UNIT": RETURN 2150 PRINT "VA LUE BEYOND RANGE OF TEST": RETURN 2160 PRINT "VALUE BEYOND ZEROING LIMIT": RETURN
217 0 PRINT "NO VOLTAGE ENTERE D": RETURN
21 80 PRINT "INVALID IEEE COMMAND": RETURN 2190 PRI NT "COMP ONENT OUT OF TEST R ANGE”: RETURN 22 00 REM H W i t SUBROUTINE TESTS GOOD/BAD RESULT
######
2210 IF G D$ =■ “ " THEN PRINT "NO GOOD/BAD TEST" 2220 IF GD$ = "G" THEN PRINT "THE RESULT IS GOOD" 2230 IF GD$ - MB" THEN PRINT "THE R ESULT IS INVERSE
: P RINT ” BAD M: NORMA L :FG = 1 2240 RETURN 9997 REM
***** ********** ***********************************
9998 REM THE FOLLOWING SUBROUTINES APPLY TO
ADDRESSING THE APPLE-BRAND IEEE-488 CONTROLLER CARD
FOR THE APPLE // COMPUTER.
9999 REM
10000 REM #//### SUBROUTIN E ENABLES BUS ##### 10010 PRINT D$
10015 PRINT D$;”IN/M”: REM CARD IS IN SLOT FOUR 10020 PRINT D $;"PR#4": REM TURNS ON SLOT FOUR 10030 PRINT "LFl”: REM ENABLES LINEFEED FOR EOF
CHA RACTER 10040 RETURN 10100 REM ##### S UBROUTINE RETURNS TO KEYBOARD ##//#// 10110 P RINT D$;"PR#0 ": REM RETURN S OUTPUT TO CRT 10120 PRINT D$;"IN#0": REM RETURNS INPUT TO KEYBOARD 10130 RETURN 10200 REM ##### SUBROUT INE FINDS TALK/LISTEN ADDRE SSES
mu
10210 REM RETURNS TALK ADDRESS IN VARIAB LE TA$ 10220 REM R ETURNS LISTEN AD DRESS IN VARIABL E LA$ 10230 VTAB 7: HTAB 6: INVERSE : IN PUT " ENTER PRIMARY
ADDRESS:";K$: NORMAL 10240 AD » VAL (K$) 10250 IF AD < 1 OR AD > 30 THEN HOME : VTA B 9: PRINT
G$;G$;" ADDRESS MUST BE BETWEEN 1 AND 30": FOR X - 1
TO 500: NEXT X: GOTO 10230 10260 LA = AD + 32: REM CALCULATE LISTEN ADDRESS 10270 LA$ = "WT" + CHR$ (LA) 10280 TA - AD + 64: REM CALCULATE TALK ADDRESS 10290 TA$ = "RD" + CHR$ (TA) 10300 RETURN 10500 REM ##### SUBROUTIN E COMMUNICATES WITH BUS
#####
10510 REM DATA MUST BE IN DA$ BEFORE CALLING 10520 REM LISTEN AND TALK ADDRESSES ARE IN LA$ AND TA$ 10530 I -■!: REM SET LOOP COUNTER TO NORMAL 10540 IF DA$ = "LKI" OR DA $ = "LKR" THEN-I = 3 : REM
TAKE THIRD LEAKAGE READING
10550 PRINT LA$;Z$;DA$: REM SE ND LISTEN ADDRESS AND
COMMAND 10560 FOR N - 1 TO I 10570 PRINT T A $ ; Z $ ; : REM SEN D TALK ADDRESS 10580 INPUT RZ$: REM COLLECT READING IN RZ$ 10590 NEXT N 10600 RETURN
Fig. 39 — Sample program using the Apple lie as a cont roller wit h an Apple IEEE-488 controller card installed. To
use the Apple lie with a differen t control card change lines 10,000-10,600 accord ingly.
41
15
This sample program is written for the Fluke 17XXA Instrument controller. It illustrates the bus operation of the LC77 and command syntax needed to automatically analyze a capacitors or
inductors. Writ te n by Sencore, this program may be used 'as i s or may be modified as needed by any IC77 owner without any further permission from Sencore, Inc.
LC77 i s at IEEE address 10
6 0 | ** * ** * ** * ** a- ** * * * * ** * * * * * ** * * * * * * *** *★{
100 DIM C(10),C$C12) 110 TIMEOUT 0
120 INIT
130 CLS=CHR$(27)+' 12 J ' 140 PRINT CPOS(Q,0)+CL£ 1000 ! *** Enter Capacitance Test Data ***
1010 PRINT. CLS 1020 PRINT CPOS(5,30)+<1 Aluminum Lytic1; 1D30 PRINT C P O S C d ^ O ) * ^ Double Layer Lytics'; 1040 PRINT CPOS(7,3D)+*3 Tantalum caps1; 1050 PRINT CPOS{8,30)+*4 Ceramic caps'; 1060 PRINT CPOS(9,30)+'5 All other caps'; 1070 PRINT CPOS(11,30)+'Enter the capacitor type*;\IHPUT C(1) 1080 ! C{1>=capacitor type 1090 IF C (1)<>1 AMD C(1)<>2 AND C<1><>3 AND CC1)<>4 AND C(1)<>5 THEN 1010 1100 PRINT CL$+CPOS(8,0)+'Enter the capacitor working voltage1 ;\INPUT C(2) 1110 ! C(2)=capacitor working voltage 1120 PRINT CL$+CPOS(8,0>+'Enter the capacitor value (.01uF)'; 1130 INPUT CS(D) 1140 ! C$C0)=capacitor value
iiaCi ('K»«i uL*>-fCKUai£>J0^ T -e n te r trte ca p a c it or to l e ra n c e1;\ i m J i !;(*()
1160 ! C(4)=capacitor tolerance 2000 ! *** IC77 Lead Zero *** 2010 LC$*CHR$(27)+' [2K'\C$(5)=LC$\C$C4)=LC$ 2020 C$(2)-LC$\C$(3)=LC$ 2030 PRINT 310, >CPO' 2040 PRINT CL$+CHRS(7) 2050 PRINT CPOS(8,22)+'Open then leads and touch the screen’ 2060 WAIT FOR KEY\K%=KEY 2070 PRINT CL$+CHR$(7%> 2080 PRINT 310 , 'IDO' 2090 INPUT 310,2$ 3000 ! *** LC77 Test Data Set-up ***■ 3010 PRINT CL$+CHR$(77.) 3020 PRINT CP0S(8,10); 3030 PRINT 'Hook the leads to the capacitor to test and touch the screen1' 3040 WAIT FOR KEY\K%=KEY 3050 PRINT CL$+CHRS(7%) 3060 T1$=MID(1 ALMDBLT ANCERAOC , (C(1 )*3 %)-2%,35! ) 3070 C$(6>=*‘ 3080 FOR J%=1 TO LEN(C$(0>) 3090 T2$-MID(C$(0),J%,1%) 3100 IF INSTR(1%, 'upfUPF' ,T2$) THEN C${6)=C$C6>+T2$ 3110 IF INSTR(1%,'„0123456789',T2$) THEN C£{7)=C$(7)+T2S 3120 NEXT JX 3130 PRINT 810,11$ 3140 PRINT 310,C(2);'V* 3150 PRINT ai0,VAL(CS(7));C$(6)
3160 PRINT S10,C<4); 3170 PRINT ai0,C(4);1
4000 ! *** Capacitor Value Test Routine *** 4010 PRINT 310, 'CAP' 4020 INPUT 310,C$(t) 4030 I F MID(C$(1),15%,1X)='G‘ THEN C$<8)='Good' ELSE C$<8>='Bad' 4040 I F LEFT(C$(1),3)<>'ERR' THEN CS(1)=MID(CS(1),4%,11%) 4050 Z1$=MID{' FuFpF',(INT(VAL(RIGHT(C$(1), 10%))/6?D*2%)+1%,2%) 5000 ! *** Capacitor Leakage Test Routine *** 5010 PRINT S)10 ,'LKI' 5020 INPUT 310,C$(2) 5030 IF LEFT(C$(2),3%)='ERR' THEN C$(2)=CNR$(27>+'t2K'\GQT0 8010 5040 I%=INSTR(1%,C$(2),1 -') 5050 IF i%<4% OR I%>10% THEN I%=3% 5060 C$(2)«NUMS(VAL(MID<C$(2), ISS +1%, 10%-1%))) 5070 PRINT 310, 'LKR1 5080 INPUT ai0,C$C3) 5090 C$(3)=NUM$(VAL(HID(C$(3),4%,?%))} 5100 IF VAL(C$<3))=8888 THEN C$(3)=CHR$<27)+<t5m8888'+CHR$(27)+‘[m* 5110 IF C(1) =2 THEN 6060 6000 ! *** Capacitor Delectric Absorption Test Routine *** 6010 PRINT 810, 'D/A1 6020 INPUT aiO,C$<4) 6030 S F MID<CS(4),15%,1%)='G' THEN C$<11)='Good‘ ELSE CS<11)=*Bad' 6040 IF LEFT{C$(4>,3%)='ERR> THEN C$(4)=LC$\GOTO 6060 6050 C$<4)sNUM$(VAL(MID{C$(4},4%,7%))) 6060 IF C(1 )>3 THEN 8010 7000 ! *** Capacitor ESR Test Routine *** 7010 PRINT S10,'ESR‘ 7020 INPUT 310,C$(5) 7030 I F KID(C${5),15%,l/O^'G* THEN C$( 12)-'Good' ELSE C$(12)='8ad' 7y4u L3>iD)=NU(iiiv ALi«iutt;st;3j,4X,rx))) 8000 i *** Display Results on Screen *** 8010 PRINT CLS 8020 PRINT 810, 'CPO' 8030 PRINT CPOS(4,25)+*Vatue 8040 PRINT CPOSC4,65)+C$C8) 8050 PRINT CPCS{5,25)+'Leakage ( c urrent )--- 8060 IF C$(2)<>LC$ THEN PRINT 'uA<;CPOS(5,65);CS(9) 8070 (PRINT CPOS£5,65)+C$(9)
8080 PRINT CPOS<6,25)*'Leakage (resistance) -• *;C$(3);
8090 IF C${3)<>LC$ THEN PRINT CHRS (24);!CPOS(6,65);CS(10) 8100 PRINT CPOS(7,25)+'Dielectric Absorption - l;C£(4); 8110 IF C$(4)o LC$ THEN PRINT ;CPOS(7,65);C$(1l) 8120 PRINT CP0S(8,25)+'ESR 8130 IF C$(5)<>LC$ THEN PRINT CHR$<24);CPOS<8,65);C$<12> 8140 PRINT CPOS(14,25)+'Touch the screen to rerun the program' 8150 WAIT FOR KEY\K%=t<£Y 8160 PRINT CHR$(7%)
8170 GOTO 13 0
.............
. . . . . . . . . . . . . . . l;CS(5);
';VAL(LEFT(C$(1),7%>);21$;
>;C$(2);
Fig. 40 — Sample program using a fluke controller.
42
Notes
43
APPLICATIONS
Introduction
The procedures explained in the Operation Section of this manual explain how to use the LC77 “Auto-Z”. Once you become familiar with the basic operation of the “Auto- Z”, ybu will discover many additional appli cations of the unit. This section will provide you with further information on using the LC77 features for ex tended capacitor and inductor tests, as well as other special applications.
Identifying Capacitor Types
Capacitors are often grouped according to the kind of dielectric that is used to separate the plates, and are named accordingly. For example, an aluminum elec trolytic capacitor has an aluminum oxide dielectric. While a mylar capacitor uses mylar dielectric. (Refer to the Appendix for an explanation of dielectric and other capacitor theory).
Many different types of capacitors are used in elec tronics. Each type has certain properties that ma.ke it
better suited for particular applications. Properties such as temperature coefficient, ESR, dielectric absorp tion, leakage, voltage break down, and frequency
characteristics are taken into account when selecting
the capacitor type to be used. When troubleshooting a circuit, it is not important to know why a certain type of capacitor was selected. It is best to simply replace a bad capacitor with a good capacitor of the same type value and voltage rating. This is especially true when the component is in a “Safety Critical” circuit. Because different capacitor types have different characteristics, it is important that you know what type of capacitor
you are testing in order to know if the LC77 test results
are 'acceptable or not. Capacitors are divided into five different types for test
ing with the LC77. Each has different parameters which require different good/bad limits. These five
capacitor types have different physical characteristics to determine an unknown capacitor type. These charac teristics are explained in the following paragraphs and
are summarized in Figure 41.
Aluminum Electrolytic Capacitors
i _ a
K J
T
Tantalum Capacitors
+ Pola rity Indicat o r
+ Polarity Indicator
fl'pie
Ceramic Capacitors
Double Layer Electrolytic Capacitors
(Typically much smalle r physica lly than similar
val ue Alumin u m Lyti cs. V alue usually marked in F.)
Pofarity Indicator
+ Polarity Indicator
+
Roun d corner
indicates + le a d
Mo rou nded corners, long tead is positive
S3
Fig. 41 — Each capa cito r type m ay be identified by its unique physi ca l characteristics.
44
Almniiium Electrolytics
Aluminum electrolytic capacitors (aluminum lytics)
are the easiest capacitor type to identify. They are most commonly cylinder shaped and have radial or axial leads. Large value aluminum lytics often have screw
term inals or solder lugs. The case of an aluminum lytic
usually is rolled in or formed out near the lead end to
hold the end cap and seal. All aluminum lytics have a
seal tha t is soft and rubber like to allow gasses to vent. Depending on the physical size of the case, the soft seal
may make up the entire end of the case, or it may be
just a small section of a hard end cap. Aluminum lytics
have the largest physical size to capacity ratio of all
capacitor types. These capacitors may also have several sections, with each section having a different capaci
tance value but sharing the same negative term inal,
usually the case. This is unique to aluminum electroly
tics, and whenever you encounter a capacitor having
several different capacitance value sections, it will be
an aluminum electrolytic. Because of their unique physical characteristics, most
aluminum lytics usually aren’t easily confused with other capacitor types. Axial lead aluminum lytics, how ever, may possibly be mistaken for axial lead tantalum lytics. The lead weld, shown in Figure 43, is an identify ing characteristic of the tantalum in electrolytic and is a quick way to differentiate between an axial lead aluminum lytic and a tantalum lytic. Aluminum lytics do not have a lead weld on either terminal.
leads. Lead polarization is often the only way to distin
guish a tantalum lytic from another type of capacitor. Once you become familiar with the polarity markings used, tantalum lytics are not difficult to identify. The polarity markings are not meant to be difficult to notice or understand, although if you are not aware of them, they might be overlooked. Pay careful attention so that you do not overlook the polarity indication and misiden- tify a tantalum capacitor as another type.
The simplest and most common polarity indicator is a
“ + ” sign near one of the leads. This is often used along with a second type of indicator. Figure 44 shows several examples of lead identification used in tantalum
capacitors. In addition to the “ + ” sign, each capacitor
shown has a second indication of the “ -f ” lead: a lead
weld, a tapered case, a rounded comer, a line, or an
extra ridge near the “ + ” lead.
Fig. 43 — Axia l lead tantalum capacitors, like the one
shown here, are eas ily identified from axial lead
aluminum electrolytics by a solder weld on one end.
A “ + ” ■ indicator is not printed on all tantalum capacitors. In many cases the polarity indicator will simply be the lead weld, a tapered case or rounded corner, a line, or an extra ridge on the case. Several other polarity identifiers are also used. The end or side nearest the plus lead may be painted one color. Also at times, just a dot or a line on the side of the package will be used.
Fig. 42 — All al umi num electr olytics have a rubber sea l.
Tantalum Electrolytics
Dipped tantalum electrolytics are rapidly replacing aluminum lytics in many electronic circuits. They have less leakage and higher value tolerances than aluminum lytics. Tantalum electrolytic capacitors are about one half the size of a similar aluminum electroly tic of the same value and voltage rating.
The most common shapes of tantalum capacitors are illustrated in Figure 41. While they may have many
shapes, tantalum capacitors always have polarized
NO TE: Tantalum capacitors may use dots or s tripes to
in dica te value or toleran ce. Do not confuse the value
color c ode for the polarit y indicat or of a ta ntalum
capac it or. T he polar ity indicator will be l arger and iso la t ed fro m th e color code.
Fig. 44 — Tan talu m el ectrolytic capacitors always
have a polarity indicator.
45
i ■
f
+
Fig. 45 — A tantalum chip capacitor (left) can be iden tified from a ceram ic chip capacitor by its positi ve lead.
Tantalum capacitors are also available in the small
surface mount or “chip” type. Tantalum chip caps could be confused with the ceramic chip cap, since they are similar in size and appearance at first glance. But as Figure 45 shows, a tantalum chip capacitor is polarized and has an easily identifiable positive lead. The polarity identification that may give you the most difficulty in identifying a tantalum capacitor is lead length. The only identification of the positive lead on some tan talum capacitors is that it is longer than the other lead. Of course, this presents no problem when the capacitor is new, but once it has been installed into a circuit board, the leads are cut off to the same length. In this situation, use the circuit, as the clue to the cap’s type and polarity.
Double Layer Electrolytics
Double layer electrolytic capacitors are commonly known by trade names such as “Supercap” or “Gold Cap”. These capacitors are quite easy to identify. Dou ble layer lytics have an extremely large capacitance value for their physical size. They are found in various physical shapes and sizes, as shown in Figure 46. Their value is marked in Farads, rather than in picofarads or microfarads.
Ceramic Capacitors
Ceramic capacitors may be found in many different sizes and shapes. The most common type of ceramic
capacitor is the flat, round ceramic disc, as shown in Figure 47. The ceramic disc is unique in its shape, and is easily identifiable from other ceramics, and other types of capacitors. The ceramic disc is also unique from other types of ceramic capacitors in that it may have small amounts of normal leakage.
Fig. 47 — Th e most common type o f ceramic capacitor
is the ceramic disc. It has unique parameters which
require it to be tested differently than o ther ceramic,
or film capacitors.
Two other kinds of ceramic capacitors which are easily
identified from other capacitor types are the axial lead
and chip types. As Figure 48 shows, some axial lead
ceramic capacitors may look the same as resistors and
inductors which also use the same case type. You can
easily determine if the component is a resistor,
capacitor or inductor from its location in the circuit.
The LC77 can also be used to help identify these un
known components, as explained in a following section,
“Identifying Unknown Components”, on page 48.
The polarity of a double layer lytic is often printed on the case, although a longer lead may also be used to identify the positive terminal. Some double layer lytics use a line next to one lead which may be either “ + ” or
If there is no other marking, the terminal that is
part of the metal case is the negative lead.
I
Fig. 46 — Double layer lytic capacitors have a very large amount of capacitan ce for their physical site. the ir value i s usually mar ked in Farads.
Fig. 48 — Ceramic capacitors ma y also include an
axial lead and chip-type pac kag e. Axial lead ceramics
oft en look like other axial lead components .
Ceramic chip capacitors are unique in their appearance.
Only a tantalum chip capacitor looks somewhat alike. However, as shown in Figure 45, a tantalum chip
capacitor has a recognizable polarity indicator. A
ceramic chip capacitor does not.
There are a few other kinds of ceramic capacitors be
sides the three types identified here. These types, such
as molded ceramics and encapsulated ceramics, are
very similar in appearance to film capacitors, and are
difficult to differentiate from films by physical appear
ance. This presents no problem though, when testing
these ceramics with the LC77, since any leakage or
D/A in a ceramic capacitor, other than a ceramic disc,
is not allowable. If you are unable to identify the
capacitor as a ceramic, test it as an “ALL OTHER
CAPS” type.
All Other Capacitors
The final capacitor type capitalized grouping for LC77
“Auto-Z” good/bad testing is “ALL OTHER
CAPACITORS”. As its name implies, capacitors in this
category do not have the electrical (or physical) charac
teristics to fit into any of the other categories.
Capacitors included in this grouping are films, micas, air dielectrics, papers, oil filled capacitors, and other similar types. (There are numerous types of film capacitors such as mylar, polyester, polycarbonate,
polystyrene, and polypropylene). Though each of these
capacitor types have different dielectrics and somewhat
different parameters, they are all similar in that when
tested with the LC77, they should have no dielectric
absorption or leakage. Also, because of their relatively low capacitance value, ESR is of little importance and is not measurable. If you measure any leakage, or D/A
in an “All Other Capacitor” type it is bad.
NOTE: Wh en replacing any of these capacitors, always replace it wit h the s ame typ e origina lly us ed in the cir cuit. For exampl e, a m yla r film capa citor should only
be repla ced wit h anothe r my lar film . This is especi ally important for components in areas of t h e sche matic de signa ted a s “Safety Critical
Identifying Inductor Types
Inductors, like capacitors, may be found in many shapes
and sizes depending on the application in which they are used. The LC77 will provide an accurate Ringer test on all types of air core and ferrite core inductors, provided the proper INDUCTOR COMPONENT TYPE switch is selected. Each inductor type has a normal range of impedance, and the INDUCTOR COMPO NENT TYPE switches match the impedance of the
LC77 Ringer circuits to the particular inductor type being tested. With the proper COMPONENT TYPE
switch selected, an inductor with just a single shorted turn will produce a “B AD” indication in the Ringer test.
Air and ferrite core inductors break into three, easy to
identify types: Yokes and flybacks, switching transfor
mers, and coils. Select one of these three INDUCTOR
COMPONENT TYPE switches when performing the Ringer test.
Fig. 49 — Yokes (top) and flybacks (bottom) are induc to r types which are eas ily identified.
Switching Transformers
Switching transformers are used in power supply cir cuits to step voltages up or down. However, they are much different from conventional power transformers in both appearance and operation, and should not be mistaken for a power transformer. Power transformers usually operate a t 60 Hz, and therefore contain a lam i nated iron core which is often visible. Because the iron
core is low Q and absorbs all ringing energy, power
transformers cannot be tested with the LC77.
Switching transformers, on the other hand, are much smaller and lighter than power transformers. They are wound around a ferrite core which easily rings when good. Switching transformers operate at much lower currents and much higher frequencies than power transformers. Two common switching transformers, the PC board mount and toroid types, are shown in Figure
50.
Yokes And Flybacks
Yokes are used exclusively in video applications to de flect a CRT electron beam. As shown in Figure 49, they can not be easily mistaken for any other type of induc tor. Yokes have a ferrite core, surrounded by two pairs
of windings, which fits over the CRT neck. It is held in place with a plastic shell attached to the CRT neck.
Flyback transformers are also easy to identify. They
too are used exclusively in video applications, and pro
duce high voltage for the CRT. A flyback has several
terminals which are often soldered to a PC board chas
sis. One or two heavily shielded leads exit the flyback
to carry high voltage to a tripler, or to the CRT directly.
HP
Fig. 50 — The torriod (left) a nd PC mount are two
common types o f switching transformers.
47
Coils
All non-iron core inductors which can not be classified
as yokes, flybacks, or switching transformers are tested with the “Coils” INDUCTOR COMPONENT TYPE switch selected. These include RF/IF transformers, RF chokes, postage stamp inductors, axial lead inductors, free form coils, as well as some other types.
..
Fig. 51 — Air and fer rite core in ductors a re tested with the “co ir component type switch selected.
You can use the LC77 tests to sort these component types from each other. Figure 53 shows, in flow chart form, the procedure you need to follow. Before begin
ning the test, zero the test leads in both the “Short”
and “Open” position of the LEAD ZERO switch. You begin identifying the component with a capacitor value test. Depending on the reading, you either use the leak
age test or inductor value test to further isolate the
component. Finally, if the component appears to be an
inductor, you use the ringing test as confirmation.
Connect Unknown Capacitor Inductor or Resistor
Identifying Unknown Components
Occasionally you may encounter small value inductors
and axial lead ceramic capacitors which look like the more common axial lead film resistor. If these compo nents get mixed up in your parts bin, you may have difficulty identifying the component. This may also be
a concern with chip capacitors, chip inductors, and a few7 other axial lead inductors and capacitors on which the markings are difficult to interpret or are not visible.
Fig. 53 — Use this flow chart to help identify small axial lead inductors, capac itors, and resistors from one another.
----------------
IMPORTANT-----------------
Do not apply more than 10 volts across an unknown capacitor, resistor or inductor. Most chip, “film” package, and axial lead in ductors and capacitors will have voltage rat ings greater than 10 volts, If in doubt about an unknown component’s voltage rating, use
another method to identify it, if possible, or
use a lower test voltage.
Fig. 52 — Som e small value inductors (left) capacitors
(center) and resistors (right) maybe hard to tell apart. The LC77 provides a quick test to identify such un
known components.
NO TE: This test is only intended to help yo u sort induc
torscap ac itors and resist ors in “film resis tor” type, chip type or small axial lead packages which are difficult to
ident ify by ph ysical appearanc e or any other means .
48
Capacitor Testing Applications
Checking Leakage Between Sections
Of A Multi-Section Lytic
Interpreting Capacitor Value Readings
The LC77 “Auto-Z” automatically displays the three most common capacitor values of picofarads (pF), micro farads (uF), and Farads (F). When measuring capacitors with the LC77, you may encounter some capacitors with
a value marked without a decimal, such as “25000 pF”, but that read “.0250 uF” on the LC77 display. You may also encounter, as an example, a capacitor which is marked “3300 pF” by some manufacturers, yet an iden tical replacement is marked “.0033 uF” by another manufacturer.
As these examples illustrate, capacitors can be marked in pF, uF or even F. A fourth value multiplier, the nanofarad (nF) is seldom used to mark a capacitor, but is used occasionally in design and industry. Table 12 will help you to easily convert from one reading to another.
Change to From
Farads
Microfarads
Nanofarads
Picofarads
Farads
move decimal 6 places [eft
move decimal 9 places left
move decimal
12 places left
Multiple section aluminum electrolytic capacitors are common, especially in many older power supplies. Such capacitors are actually several capacitors, inside one can, sharing the same negative terminal.
Leakage sometimes develops between one or two sec tions of multi-section lytics. This leakage is especially difficult to troubleshoot without the LC77 leakage test because signals from one section of the capacitor are coupled to another section. This results in multiple symptoms in the operation of the device in which the capacitor is used. An ohmmeter will not show leakage between sections of a multi-layer cap because the leak age only occurs near the capacitor’s operating voltage.
To isolate this type of leakage with the LC77 you simply perform the standard leakage test. As you test each section, short each of the remaining sections to ground. Any increase in leakage when a section is shorted to ground indicates leakage between sections.
Microfarads
move decimal 6 places right
move decimal 3 places left
move decimal 6 places left
Nanofarads
move decimal 9 places right
move decimal 3 places right
move decimal 3 places left
Picofarads
move decimal 12 places to right
move decimal 6 places right
move decimal 3 places right
Table 12 — Capa citor value convers ion chart.
Dielectric Stress
Many ceramic capacitors change value when they are
DC biased. The applied DC voltage causes physical
stress within the ceramic dielectric causing it to de crease in value. This value change is called “dielectric stress”. Normally a ceramic capacitor will return to its normal value within several seconds after the voltage is removed.
You will not normally notice dielectric stress when checking a ceramic capacitor with the “Auto-Z”, unless you apply a voltage to it with the capacitor leakage test. Then you may find that the capacitance value has decreased by as much as 50% in ceramic capacitors having values 10 pF or smaller. This is a normal charac teristic of small value ceramics.
Fig, 54 — Test the leakag e of one section of a multi- section l ytic, then shor t one of the re maining sections to ground, Any increa se in lea kag e curr ent in dicates leakage between that se ction and ground.
49
-WARNING-
This test should only be performed by a per
son who understands the shock hazard of up to 1000 volts applied to the test leads during the capacitor leakage test. DO NOT hold the capacitor in your hand, or touch the test leads or capacitor leads when making this leakage test.
Simply connect the capacitor to the LC77 and measure its value. Then apply heat to the capacitor while you continue to measure its value. A COG or NPO type capacitor will not change in value, or change very slightly as heat is applied. An N type ceramic will de crease in value, while a P type ceramic will increase in capacitance.
Checking Capacitance Of Silicon Diodes And Transistors
To check for leakage between sections of a multi layer cap:
1. Connect one section of the capacitor to the LC77 test leads. Be sure to observe proper polarity.
2. Enter the working voltage of the section being tested. Note that a multi-layer lytic may have a different work ing voltage for each section.
3. Depress the CAPACITOR LEAKAGE button and read the leakage current on the LCD display. It must
be within the maximum allowable leakage limits for
its value and voltage rating.
4. Connect one end of a short jumper to the common
terminal of the capacitor.
5. While depressing the CAPACITOR LEAKAGE but
ton, connect the other end of the jumper to each of the
capacitor terminals not already connected to the L077
test leads.
6. A good multi-section electrolytic will show no in crease in the leakage reading as the jumper is connected to each terminal.
Intermittent Capacitors
Occasionally an electrolytic capacitor may become in termittent. A poor weld of the lead to the internal foil plates or other mechanical problem can cause the capacitor to function randomly. Often such capacitors will also exhibit high ESR when they are working. (The internal construction of an electrolytic- capacitor is shown in the Appendix).
If you suspect an intermittent capacitor, move its leads around and pull on them as you perform a capacitor value test. A change in capacitance indicates an inter mittent component which should be replaced.
Checking Ceramic Capacitor
Temperature Characteristics
The capacitance of silicon diodes and transistors, as well as the reverse leakage paths of silicon and ger manium transistors can be easily measured using the LC77. Figure 55 shows the connections necessary for
these measurements. If the LC77 display shows “0.0 pF” when testing capacitance, or flashing “88.88 mA” when testing leakage, the connections are reversed. No
special precautions are necessary when measuring
capacitance, however be sure to follow these precau tions when testing leakage:
1. Do not apply more than 3 volts to a transistor when
testing Ibeo.
2. Set the leakage supply to the maximum voltage rat ing of the transistor when testing Icbo or Iceo, but do not exceed the rated voltage. Exceeding the rated vol tage may cause the transistor to zener, and will damage the junctions.
NO TE: The capacita nce of germanium tra nsi sto rs and
diodes can no t be measured with the LC77 b ecaus e of their high leakage. Leakage tests o f ge rmanium devices are the same as for silicon devices.
PNP
Black
ICBO an6^
B to C Cap a c i t y
/
Red
*
Red
\
(BEO a n d
B to E Cap a c i ty
^Biack^
Red
\
ICEO and
E to C Ca p ac i ty
jg S ' ICBO a n d
B to C C a p ac it y
Slack
k
Black
\
IBEO a n d
B to E Cap a c i ty
'"Red
NPN
Red-fc*
Black
iCEOan d
E to C C a p ac i ty
Red
Ceramic capacitors are designed to have a wide range of capacitance value and temperature characteristics, (More details are given in the Appendix.) Replacing a capacitor with one that has the same characteristics is especially important in certain oscillators and other temperature critical circuits. You can quickly deter mine the basic temperature characteristics of a ceramic using the LC77 and a heat source, such as a heat gun.
Red
Fig. 55 — Th e connectio n for measuring the capac i tance of silicon junctions and lea kage paths for silicon
and germani um junctions.
w
Reverse Leakage
and
Junction
Capacity
Black
Junctions are shown Reverse bias. Ex change Red and Black for forward con duction.
50
Testing High Voltage Diodes
Reforming Electrolytics
High voltage diodes, such as those found in video high voltage and focus voltage sections may require up to 200 volts before they are forward biased and begin to conduct. They cannot be tested with an ohmmeter since, with only a few volts applied, a good high voltage diode will simply indicate “open” no matter how the ohmme ter is connected.
The capacitor leakage test of the LC77 provides suffi cient voltage to bias high voltage diodes into conduction and also to test them for reverse breakdown. Test the diode for normal forward conduction first. Then reverse the test leads and check for reverse leakage.
I J -I u -
"
.....
"■..
.....Pr..Pr..
Fig. 5 6 — To test a high voltage diode, enough voltage is neede d to forward bias all the ju nctions.
J J J -I -I 1
?
n i i I I 1
WARNING -
This test should only be performed by a per son who understands the shock hazard of up to 1000 volts applied to the test leads when the the CAPACITOR LEAKAGE TEST button is depressed. DO NOT hold the diode in your hand, or touch the test leads or diode leads when making this test.
To test a high voltage diode:
1. Connect the red test lead to the diode anode end) and the black test lead to the diode cathode (“ + ” end).
2. Enter 50 volts into the leakage supply and depress the CAPACITOR LEAKAGE TEST button.
3. If the LC77 display shows no leakage, apply more voltage until the diode begins to conduct, as indicated by a leakage current reading of 100 uA or greater.
Aluminum electrolytic capacitors often decrease in
value and develop leakage if they sit unused for long
periods of time. (This is often the case with electrolytics on stockroom shelves or in parts bins). These symptoms are caused by the loss of some of the oxide dielectric. The oxide is formed by a chemical reaction in the elec trolyte when voltage is applied to the plates. With time, this oxide deteriorates. In many cases the electrolyte has not dried up and the oxide coating can be reformed
by applying a DC voltage to the capacitor for a period of time.
You can use the LC77 leakage test power supply to reform the dielectric. Reforming may take an hour or longer before the capacitor reforms and the leakage drops to a normal amount.
Use the 39G201 Test Button Hold Down Rod supplied
with the LC77 to hold the CAPACITOR LEAKAGE TEST button depressed while you are reforming the capacitor. The hold down rod fits between the CAPACITOR LEAKAGE TEST button and the carry ing handle, and can be adjusted longer or shorter as needed. A hold down rod rather than a locking button is used as a reminder to you and others that voltage is being applied to the test leads.
-----
—
------—WARNING
Use the 39G201 Test Hold Down Rod with ex treme caution. Do not touch the test leads or the capacitor leads while the Test Hold Down
Rod is being used. Voltage up to 1000 volts is
present when the CAPACITOR LEAKAGE
TEST button is depressed. Make sure that the capacitor being reformed will not touch or come in contact with any metal object while voltage is applied to it.
-------------------
£ITQfl - IND UCT OR ANALYZER
4. Once the diode begins to conduct, do not apply any higher voltage as this will cause excessive current flow through the diode and damage it.
5. If you apply 999.9 volts to the diode and it still shows
no conduction, it is open and you do not need to continue
the test.
6. When the diode begins to conduct, release the CAPACITOR LEAKAGE TEST button and reverse the test lead connection to the diode.
7. Set the leakage power supply to the PIV (peak inverse
voltage) of the diode shown in a replacement guide. If
the PIV is greater than 1000 V (as it will be for most high voltage diodes) set the leakage power supply to
999.9 volts.
8. Depress the CAPACITOR LEAKAGE TEST button and read the leakage current. A good high voltage diode will typically show less than 2 uA of reverse current.
VALUE
ABSO RP
TEST
CAS
TE R/RE C A LL
r
%
Fig. 57 — The Test Button Hold Down Red keeps the
CAPACITOR LEAKAGE but ton depressed when re forming capacitors.
51
V
c a p a c i t o r
DIELECTRIC
To reform an electrolytic:
1. Connect the capacitor to be reformed to the test leads.
2. Enter the rated voltage of the capacitor into the LC77.
3. Depress the CAPACITOR LEAKAGE TEST button, and while holding it in, place the 39G201 Test Button
Hold Down Rod between the button and the handle.
4. Adjust the length of the rod by holding one end and turning the other until the hold down rod keeps the CAPACITOR LEAKAGE TEST button depressed.
5. After the capacitor has reformed for at least one hour and the leakage has dropped to a normal amount, allow it to set for 30 minutes. Then recheck the value and leakage to see if reforming has improved the capacitor,
Often an inductor mounted in-circuit has leads whiq are too short to attach the test lead clips to. The (oj tional) 39G85 Touch Test Probe is especially useful fc measuring such coiis. It provides 2 needle-sharp point which will pierce through the coating on the foils allow ing contact to the coil leads.
---------------i-----
WARNING----------------------
NEVER use the Test Button Hold Down Rod
to hold in any button except the CAPACITOR
LEAKAGE TEST button. Damage to the LC77
may result if it is used to latch another button
since the protection circuits inside the LC77 are bypassed when a test button is depressed. The warranty will be voided if the LC77 is damaged by connecting a charged capacitor
or any other voltage to it with any of the other buttons held in with the Test Button Hold
Down Rod.
Inductor Testing Applications
Testing Inductors In-Circuit
The LC77 “Auto-Z” can be used to measure the induc tance of a coil with the component still in circuit. In-cir- cuit inductance measurements, however, may be af fected by the impedance of the circuit. Low values of parallel resistance will lower the circuit impedance and cause the LC77 to measure a lower inductance value. Table 13 lists the amount of parallel resistance which will cause a 10% or less change in the measured induc tance. Resistances larger than the amounts shown will
not have a significant effect on the inductance test. '
In duct or
1 uHto 18uH
18 uH to 180 uH .
180uHto1.8mH
1.8mHto18mH
18 mH to 180 mH
180 mH to 1,8 H
1.8 H to 20 H
Table 13 — Inductors may be measu red in-circuit if the parall el resistance is greater than the amounts listed here.
NOTE: G ood inductors may not n or mally ring if con
ne cted in-circuit, unless the paralleled impedan ce is
quite high. However, if an inductor does ring i n-c ircuit,
it is good.
Val u e M i n imum P aral l e l Re s istance
10to 100ohms 25 to 200 ohms 50 to 5 00 ohms
150 ohms to 1.3 kilohms
400 ohms to 3 kiiohms 800 ohms to 7 kiiohms
5k to 25 kiiohms
Fig. 58 — Use the option al touch test probe to measure inductors mounted on PC boards .
Mutual Inductance
Mutual inductance occurs when two or more coils are I wound on the same form and connected together. In i
such cases, the total inductance measured across the ! windings will not equal the sum of the measured indue- ; tances of the individual coils. This is due to the mutual I inductance of the coils. The total measured value may j
be higher or lower than the individual inductances, !
depending on whether the coils are aiding or opposing.
In addition, the effects of mutual inductance depend on j the type of core material, the spacing of the turns, and the type of turns used. The amount of inductance mea
sured by the “Auto-Z” will be the same inductance seen ; by the circuit.
Q-g-nrem
...
,« rro y i
___
q j
f 1 0 0 0 uH tt I'OQOuH t t 100 0 uH ff 1 QQQ uH f
t________ 2280 u H
(W h e n M u t u a l i nd uctan c e A d d s) (W hen Mut u a l I nd uc tan c e
Fig. 59 — The e ffects of mutual ind uctance may add or su btract from the sum of the individu al.
Ringing Peaking Coils
Peaking coils are often wound around a resistor. The resistor serves to lower the Q of the coil to prevent ringing. For this reason, some good peaking coils will not read good on the Inductor Ringer test. The lower the resistor value, the fewer rings the coil will read.
_______
J \
_______
18 70 uH
S ub tracts)
_____
}
j
52
The best test for peaking coils is to observe the number of rings, rather than the good/bad indication, and com pare the coil to an identical known good component.
Ringing Metal Shielded Coils
Sometimes coils, such as IF transformers, may be placed
inside a shield to reduce in-circuit interference. These
shielded coils may not ring good when tested with the Inductor Ringer test because the metal shield absorbs some of the ring energy.
A shielded coil is good if it rings ten or more. However, if it rings less than ten, remove the metal shield, if possible, and test the coil again. If it now rings 10 or more, the coil is good. If you are unable to remove the metal shield, make a comparison test using an identi cal, known good component.
Ringing Flyback Transformers
A flyback transformer is a special type of transformer which produces the focus and second anode voltages f®r a CRT. Many flybacks also have several lower voltage, relatively high current windings which power other circuits and the CRT filament. Because of the high voltages present, a flyback transformer may develop an internal shorted turn. A shorted turn reduces the efficiency of the transformer and usually causes severe circuit problems. Inductance measurements are of little value when troubleshooting a flyback, since a shorted turn causes little change in inductance value. In addi tion, the inductance value is seldom known. The LC77 Inductor Ringer test will detect a shorted turn in any of the primary or secondary windings of a flyback.
A flyback transformer may be tested in or out of circuit with the LC77 Ringer test, although several external loads may need to be disconnected before a good flyback will ring. Connect the LC77 to the primary of the flyback and select the “YOKES & FLYBACKS” COM PONENT TYPE switch. Depress the INDUCTOR RINGER TEST button and read the condition of the flyback as “GOOD” or “BAD” in the LC77 display. If
the flyback rings “BAD”, disconnect any loads until the display reads “GOOD”. If the flyback is completely dis connected and still rings “BAD” the flyback has a shorted turn, or the winding, to which the test leads are connected, is open. In either case, the flyback should be considered bad.
N OTE: Certain f lyb acks have r emoveable cores. The fer rite core must be inst all ed inside the windings in order for the flyback to ring “GOOD”.
A few flybacks used in some small solid state chassis have a low impedance primary which will not ring when
good. However, these flybacks will always have a sec ondary winding which will ring good if the transformer is good. Simply ring the secondary windings. If one rings good the flyback does not have any shorted turns. If no winding rings good the flyback is bad.
A coil in the secondary of a flyback may occasionally open, rather than short. An open coil will not load the other windings as a short does. If the operation of the
chassis indicates the possibility of an open winding,
leave the LC77 connected to the primary winding and
short each of the windings with a jumper. Shorti; • u ; a winding will reflect back to the primary and cause the ring test to go from “GOOD” to “BAD”. If the ring test does not change, the winding being shorted with the jumper is open.
Fig. 60 — Connect to the prima ry s ide of a flyba ck to
do the ringing test.
r—
-------:-------— WARNING------------^— :
Do not connect the LC77 test leads to a flyback in-circuit until all power to the chassis has be removed, and the AC line cord has been dis connected.
Fig. 61 — Use a jumper to determi ne if a flyback wind ing is open. An open winding will not cause the ringing
test to change when a jumper is placed acr oss it.
-----
53
To ring a flyback transformer:
1. Connect the red test lead to the collector of the hori zontal output transistor, or to the plate cap of a horizon
tal output tube.
2. Connect the black test lead to B + side of the primary winding. In a tube set connect to the cathode of the damper diode or anode of the boost rectifier.
3. Pull the socket off the CRT (remove the high voltage rectifier tube in a tube chassis) to prevent the filaments from loading the secondary and giving a false ringing indication.
4. Depress the INDUCTOR RINGER TEST button. If the LC77 display reads “GOOD” the flyback is good, and the remaining steps are not necessary.
CRT, since a shorted winding may be caused by th pressure of the yoke mounting. Relieving the pressui; may cause the short to go away.
A deflection yoke has two sets of windings (horizonta and vertical) which must both test good. The yoke lead; must be disconnected from the circuit. This is ofter accomplished by simply pulling the yoke plug from th(; chassis. The vertical windings may often have dampinr resistors across them which also must be disconnected; These resistors may be on the chassis, in which case simply pulling the yoke plug will disconnect them.
They may also be soldered right to the yoke, meaning you will need to unsolder one side of the resistor. Test! both yoke windings with the “YOKES & FLYBACK”) COMPONENT TYPE button selected.
A “BAD” reading indicates that either the flyback has a shorted turn or that it is being loaded down. The following steps will locate the defect. Continue discon necting the loads in the following order until the flyback rings “GOOD”. If the flyback rings “GOOD” after you disconnect a load, double check that load to make sure it is not defective.
5. Disconnect the horizontal yoke windings and repeat
the ringing test.
6. If the ringing test still reads bad, remove one end of the damper diode in the solid state chassis and repeat the test.
7. If the ringing test still reads bad, unplug the con
vergence coils and repeat the test.
8. If the ringing test still indicates bad, disconnect any remaining low voltage, AGC or other windings one at a time.
9. If all the loads are disconnected and the ringing test still indicates bad, the flyback has a shorted turn.
Many flybacks used in solid state chassis have the high voltage rectifier diodes (tripler) built in to the secondary winding. Thesei flybacks are called Integrated High Vol tage Transformers (IHVTs). The Ringing test will lo cate defective turns in these types of flybacks as well. A problem with the diodes will result in problems with the high voltage, even though the Ringing test indicates “GOOD”. If the flyback rings “GOOD” but produces no high voltage, one of the diodes is open. If the high vol tage is several thousand volts too low and the flyback rings good, one or more of the diodes is shorted. In either case, the flyback is defective and must be re placed.
NO TE: Test the vertical windings in dividuall y on yokes \
that ha ve serie s connect ed vertica l windin gs. The verti- i cal win ding s should r ead within 3 rings o f each other , \ but may not n ecessarily ring “GOOD” with 10 or more ! rings. Any su ch yoke that has a ring difference gr eater \ than 3 rings , or an inductance value difference greater \
than 10 % will give pr oblems in the chassis.
r
_____________
Do not connect the LC77 to the yoke in the chassis until all power has been removed and the AC plug has been disconnected.
Fig. 62 — . Test deflection yokes with the ringing test
while the yoke is still mounted on the CRT .
WARNING
_____________
Ringing Deflection Yokes
Video deflection yokes are special inductors which are used to move a CRT electron beam both vertically and horizontally. As with flybacks, the LC77 Ringing test provides a quick and reliable good/bad test. Yokes should be tested while they are still mounted on the
54
To test horizontal yoke windings:
1. Disconnect the yoke from the circuit by pulling the
yoke plug or unsoldering the wires.
2. Connect the test leads to the horizontal winding.
3. Select the “YOKES & FLYBACKS” COMPONENT
TYPE button.
4. Depress the INDUCTOR RINGER TEST button and read the test result in LC77 display.
5. If the horizontal windings test “GOOD”, continue on and test the vertical winding. The vertical windings must also test “GOOD” before you consider the yoke good. If the horizontal winding test “BAD” the yoke is defective and there is no need to test the vertical wind ings.
To test the vertical windings:
6. If the yoke has damping resistors across the vertical winding, unsolder one end of the resistor.
7. Connect the test leads to the vertical winding
8. Depress the INDUCTOR RINGER TEST button and read the test result in the LC77 display.
9. If the vertical windings do not test “GOOD”, the yoke is defective.
Special Note On Solid State Yokes And Flybacks:
A few yokes and flybacks have very low Q for use in
certain solid state chassis. These components may not ring “GOOD” but may rather ring only 8 or 9 times. To determine if they are good or bad simply add a “shorted turn” and again check the number of rings. If the yoke or flyback is good, the number of rings will drop drastically when the short is added. A defective
yoke or flyback will not be affected by the shorted turn
and the number of rings will change only 1 or 2 counts
if at all.
L1 = Series Inductance
C1 = Shu nt Capacitance
R1 = Shunt Resistance (diel e ct ric ieakage) R2 = Series Resistance
Fig. 63— A length of coaxial cabl e con sists of capac i tance and inductance distributed throughout the cabl e’s length.
DETERMINING THE DISTANCE TO AN OPEN
A length of coaxial cable open at both ends is equivalent to a long capacitor, with the two conductors forming the plates. Every type of coaxial cable has a normal
amount of capacitance per foot, specified in picofarads
per foot (pF/ft). The capacitance per foot values for some
common coaxial cable types are listed in Table 14. The length of a piece of cable, as well as the distance to an open, is found by simply measuring the capacitance between the center and outer conductors and dividing this total capacitance by the cable’s capacitance per
foot value. If possible, measure from both ends of the cable to more accurately pinpoint the break. In most cases, the length of a cable can be determined within
1-2%.
A simple “shorted turn” is a piece of solder or heavy
gauge wire formed into a loop. Press the loop close to
the windings of the yoke or wrap it around the core or
windings of the flyback.
Cable Testing Applications
Testing Coaxial Cable
Coaxial cables and transmission lines have characteris
tics of both an inductor and a capacitor, as illustrated
in Figure 63. The LC77 “Auto-Z” can be used to deter
mine the length of a piece of coaxial cable (or the dis
tance to a break) and' the distance to a short between
the center conductor and shield. Any breakdown in the
dielectric can also be detected using the LC77 leakage
power supply.
Fig. 64 — Use t he LC77 to measure the d istance to breaks or short s in bu ried cable,
To measure the length of a cable:
1. Zero the LC77 test leads.
2. Connect the red test lead to the center conductor and the black test lead to the braided shield outer conductor of an open (unterminated) cable.
55
3. Press the CAPACITOR VALUE TEST button and
read the total capacitance of the cable.
LOCATING A SHORT IN COAXIAL CABLE
4. Divide the LC77 capacitance reading by the cable’s capacitance per foot value. This gives the length of the cable, or the distance to the break in feet.
You can also use this test to determine the length or to pinpoint a break in multiconductor cable that has 3 or more conductors. Due to variations in conductor spac ing and noise pickup, however, the accuracy will not be as good as for coaxial cable. Follow the same proce dure as above, except tie all but one of the conductors together to form the outer “shield”. Measure the capaci tance between this “shield” and the remaining single wire. You can determine the capacitance per foot for the cable using the procedure in the section “Determin ing Capacitance And Inductance Per Foot”.
NOTES: 1. T he accur acy of th e se mea suremen ts de p ends on the cable tolerance. The valu es list ed in Tabl e
14 are nom inal amounts which may very slightly (within
2%) with cable manufac turer. 2. Exces sive crimping or
clamp ing al ong the cable will chang e the total capaci tance reading .
50-55 Ohm
A coaxial cable which has a short between its cente conductor and outer conductor is similar to a very lonj inductor. The LC77 can be used to determine the dis tance to a short using the Inductor Value test. The amount of inductance per foot of a coaxial cable is not usually published by the cable manufacturer, and the; amount for the same type of cable may vary signific antly from one manufacturer to another. Therefore, to calculate the distance to a short you must first use a same length of cable to determine the inductance per! foot value, as explained in the following section. Record! this amount in Table 14 for each type and manufacturer; of cable you encounter.
To determ ine th e distance to a short:
1. Zero the LC77 test leads.
2. Connect the red test lead to the center conductor and ! the black test lead to the braided shield outer conductor ! of a shorted cable.
70-75 Ohm
Nomina! RG/U Cable Type Impedance 5B/U 8U 8U Foam 8A/U 10A/ U
18A/U
58/U 58/U Fo am
58A/ U 58C/ U 58C/U Foam 74A/U
174/U 177/U 212/U 213/U
214/ U 215/U 219/U 225/U 224/ U
Tab le 14 — Capa citance per foot values for common c oaxial cable types.
50 29.5 52 29.5 50 26 52 29.5 52 29.5 52 29.5
53.5 50 26 50 50 50 26 52 29.5 50 30-30.8 50 30 50
50
50 30.5 50 30.5 50 50
50
Nominal
CapinpF/ FT Inducta nce
28.5
30.8
29.5
29.5
30.5
30 30 30
Nomina l
RG/UCabieType 6A/U 6A/U Foam
11U
11UFoam
11A/U
12A/U 13A/U 34B/U 35B/U
59/U
59/U Foam
5S/BU
164/U
216/U
RG/U Cable Type 62/U 62A/U 63B/U 71B/U 79B/U
Nominal
Impedance
75 75 75 75 75 75 74 75 75 73 75 75
75 75
90-125 Ohm
Nomina!
Impedance
93 93
125
93
125
Nominal
CapinpF Inductance uH/FT
Nominal
20 20
20.5
17.3
20.5
20.5
20.5 20 20,5 21
17.3
20.5
20.5
20.5
Nomina!
CapinpF
Nominal
inductance uH/FT
13.5
13.5 10
13.5 10
56
3. Press the INDUCTOR VALUE TEST button and read the total inductance of the cable.
4. Divide the LC77 inductance reading by the cable’s inductance per foot value. This gives the distance to the short in feet.
No t e : To he l p pin poin t the short with gre a t e r a c c ur a c y , meas u re th e indu c t a n c e fr om both ends of the cable.
The LC77 leakage power supply also provides a good
test of a cable’s condition. Simply measure the amount
of leakage through the dielectric between the conduc
tors. Most cables have a maximum operating voltage
of 1000 volts or more and should be tested with the
LC77 leakage supply set to 999.9 volts. A few “air space”
dielectric types of coaxial cable, such as RG37, RG62,
RG71, and RG72 have a maximum operating voltage
of750 volts and should be tested at this lower voltage.
DETERMINING CAPACITANCE AND INDUCTANCE PER FOOT
The capacitance and inductance per foot values for a
particular type of coaxial cable can be determined by measuring a sample cable of known length. After measuring the amount of capacitance and inductance with the LC77, divide the total amounts by the length of the sample. Sample lengths of at least 10 feet are recommended for accurate capacitance measurements, and 25 feet for accurate inductance measurements.
To determine capacitance and inductance per foot:
1. Zero the LC77 test leads.
2. Connect the red test lead to the center conductor and
the black test lead to the braided shield outer conductor
at one end of the sample cable.
3. Leave the other end of the cable open to measure capacitance; short together to measure inductance.
4. Press the CAPACITOR VALUE or INDUCTOR VALUE TEST button and read the total capacitance or inductance of the cable.
------------------
This test should only be performed by a qual ified person who understands the shock and
safety hazards of up to 1000 volts applied to
the test leads and open ends on the coaxial
cable.
A good piece of cable should have no leakage when the voltage from the LC77 is applied between the center
conductor and outside shield. The length of the cable
being tested will make no difference on the leakage
reading. Any leakage reading indicates the dielectric is breaking down.
WARNING
---------------
—
High Potential Testing
The LC77 “Auto-Z” can be used to locate leakage cur rents as low as .1 uA, such as the leakage between PC board foils, leakage between windings of a transformer, and leakage between switch contacts and shafts. These leakage currents are much to small to be measured with an ohmmeter, but are measurable when a high voltage potential (Hi Pot) is applied with the LC77 leakage power supply.
5. Divide the LC77 reading by the length of the sample cable. Record for future reference.
USING THE LC77 TO FIND AGING CABLE
All coaxial cables exposed to the elements eventually degrade to the point where they need to be replaced. The LC77 can be used for preventative maintenance checks of coaxial cable to determine if deterioration is beginning to occur. As a cable begins to fail, the dielec tric separating the conductors becomes contaminated causing a change in the cable’s capacitance and the DC leakage through the dielectric.
All cable has a normal amount of capacitance per foot
and any significant change that occurs over a period of time indicates a developing problem. The best check
for aging cable is to measure and record the total capaci
tance of the installation when it is first installed. If the initial value is not known, you can multiply the length
of the cable by its nominal capacitance per foot. Then compare periodic capacitance measurements back to the initial amount and look for any changes. As the dielectric becomes contaminated, the LC77 capacitance reading will increase.
Fi g. 65 — Small leakage paths can be d etected with th e LC77 Hi Pot test
57
-----------:------
WARNING’
------------—
These tests are only to be performed by a per son who understands the shock hazard of up to 1000 volts applied to the test leads and to the component under test when the Capacitor Leakage button is depressed. Do not hold the test leads or the component under test in your
hands when making any Hi Pot test.
Traces on a bare printed circuit board should show no leakage when tested at 1000 volts with the LC77. Any leakage indicates contamination.on the board, or fine, hair-like projections from the etched traces shorting between the traces. The (optional) 39G85 Touch Test Probe may be used to make easy connection to the foils. It provides needle-sharp points that are adjustable for different trace spacings.
AC power transformers should be tested to make sure they provide proper isolation from the AC line. Trans formers should be tested for leakage between the pri mary and secondary, as well as for leakage between the windings and the metal core or frame. To test for leakage between primary and secondary disconnect all transformer leads from the circuit. Connect one of the
LC77 test leads to one of the primary leads and the other LC77 lead to one of the secondary leads. If the transformer has more than one secondary winding,
each should be tested for leakage. Most transformers used today have a 1500 volt break down rating and
should have 0 microamps of leakage when tested at
1000 volts with the LC77. Any leakage indicates a po
tential shock and safety hazard.
Measuring Resistors To 1 Gigohm
Focus and high voltage resistors up to 1 gigohm may be measured using the leakage power supply in the
LC77. These resistors are often much too large in value
to be measured with any other test. The “Auto-Z” will
read the resistance of these resistors without any calcu
lations.
The range of resistance which the LC77 will measure
depends on the applied voltage. Table 15 shows the
amount of applied voltage needed to produce a usable
resistance reading. Simply place the front panel LEAK
AGE switch in the “Ohms” position, set the leakage
power supply to a voltage just high enough to read the
anticipated resistance, and depress the CAPACITOR
LEAKAGE TEST button. The “Auto-Z” will display the
amount of resistance directly in ohms.
-------------------WARNING
This test is only intended to measure high vol tage resistors. Some resistors have voltage ratings of 200 volts or less and will be dam aged by high test voltages. Apply only enough voltage to the resistor (as shown in Table 15) to produce a reading.
-------------------
Table 15 — To measure restance value s up to 1
gigohm, enter the necessary lea kage vo ltage amount \ to place the restance value with in the shaded area.
Applications Of The Leakage Pow er Supply
Many times a variable voltage DC power supply is j needed in troubleshooting and other applications good !
as applying a bias voltage or powering a circuit. The i
LC77 leakage power supply may be used in these appli- ;
cations to provide voltages in 0.1 volt steps from 1-.0 to S
999.9 volts DC. Simply enter the desired voltage using ; the COMPONENT PARAMETERS keypad and use the 39G201 Test Button Hold Down Rod to keep the CAPACITOR LEAKAGE button depressed.
The amount of current being drawn by the circuit con- j
nected to the LC77 will be displayed in the LCD display |
up to 19.9 milliamps. (Currents greater than 20 mA {
will cause the LCD display to overrange). The leakage j
power supply is current limited and will not be damaged ;
by excessive current draw. When over loaded, the out- i
put voltage will drop to a level that will not damage 1
the supply. Table 16 shows the amount of current which j
the leakage power supply can provide with less than a |
10% reduction in output voltage.
leakage Current at 10% Drop In Output Voltage
...
...
j ;
.......
"j T ' j
i i
1.....i......
! ! '
| |
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j I i i
1 i
1 1
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t ' i
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r
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i !
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I ■
! 1
I
r i
...
i 1 ! I
— 1__4_
1 r
Hi
I!
- + H -
/
/
\
. .1
1
i
----
L_
.._j— —
i i
1 s 1 I 1 1 1
!
M
* i
"j '
I
T !
i i i i , i ~
§ ! ? i 1 ! 1 i j !
1 T . I t I I
■ H - i -
j 1 1 1 I
Voltage (Votts)
V ’
i ! s
i i 1
... ^
..
j
!
■ i
I !
" i !
Table 16— Current o utpu t c apabilities of the “A uto-Z”
leakage power supply.
1 11
1
i
i
j-
I
— !_ \
\
\
j- ~r
! 1 ! |
1 i
! | j
i
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58
MAINTENANCE
Introduction
The LC77 is designed to provide reliable service with
very little maintenance. A fully equipped Factory Ser
vice Department is ready to back the LC77 should any
problems develop. A schematic, parts list, and circuit board layouts are included along with this manual on separate sheets.
Recalibration And Service
Recalibration of the LC77 is recommended on a yearly basis, or whenever the performance of the unit is notice
ably affected. Precise standards are required to insure accurate and National Bureau of Standards (NBS)
traceable calibration. For this reason it is recommended
that the LC77 be returned to the Sencore Factory Ser vice Department for recalibration. The address of the Service Department is listed below. No return authori zation is required to return the LC77 for recalibration or service. In most cases, the unit will be on its way back to you within 3 days after it is received by the
Service Department at: Sencore Factory Service
3200 Sencore Drive
Sioux Falls, SD 57107 (605)339-0100.
Circuit Description And
Calibration Procedures
A complete circuit description, and a detailed calibra tion procedure listing the necessary standards and equipment, are available for the LC77 “AUTO-Z1”. These items may be purchased separately through the
Sencore Factory Service Parts Department at the ad
dress and phone number listed below.
Replacem ent Leads
The 39G143 Test Leads on the LC77 are made from a
special low capacity cable. Replacing the test leads with a cable other than the low capacity test lead will result in measurement errors. Replacement 39GI43 Test Leads are available from the Sencore Service Parts De
partment.
a
Spare” Button
The “SPARE” button on the front panel is provided to keep your LC77 “Auto-Z” from becoming obsolete. If a new or different type of component is introduced in the coming years, your LC77 may be updated by changing the EPROM chip or by changing the EPROM memory itself. Be sure to return the warranty card sent with the LC77 so that you can be notified if an update takes place.
-Display reads “OPEN” during inductor lead zeroing
-Display reads “OPEN” during inductance test
-Ringing test reads “Error 1”
-ESR test reads “Error 7”
-No leakage readings
-Readings do not change with test leads open or shorted
Fuse Replacement
The fuse for the test lead input is located behind the BNC input jack. Remove the fuse holder by turning the BNC connector counter clockwise and unscrewing the connector until the fuse is free. The BNC connector of the test leads may be used as a “Wrench” to aid in the removal of the fuse holder. When replacing the fuse holder, make sure it is screwed in tightly to prevent the connector from turning when connecting and dis
connecting test leads. Replace the fuse with a 1 Amp Slo-Blo (3AG) fuse only.
POWEK
0N&
ba t t te s t
A 8AT’TEST h L *
H |A liT 0 0Ff I g g g g ? r p W
test LEAD
LEA0 2ERO LEAKAGE
off* ■
WARNING
wobetJ.c77
Fig. 66 ~ Remove the TEST LE AD BNC jack to replace the input protection fuse.
DisplayTest
The LCD display of the “Auto-Z” LC77 may be tested at any time by performing the battery test and pushing the CLR button at the same time. All the segments of the LCD readout will momentarily turn on followed by
a sequential readout of all the numbers and symbols on the display. Any missing segments, symbols, or num
bers indicate a defect either in the display itself or an
internal circuit. In this case the Sencore Factory Service Department should be called for service instructions.
•
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Blown Fuse Conditions
A 1 amp, Slo-Blo (3AG) fuse is located in the test lead
input j ack on the front of the “Auto Z“. This fuse protects
the unit from accidental external voltage or current
overloads. The fuse may need replacement if the follow
ing conditions exist:
Fig . 6 7 — Push the “CLR" button while holding the power switch to “ON & BATT TEST” to check LCD display.
59
APPENDIX
Introduction
The capacitor is one of the most common components used in electronics, but less is known about it than any component in electronics. The following is a brief exp lanation of the capacitor, how it works, and how the “Auto-Z” measures the important parameters of the capacitor.
Capacitor Theory and the “ Auto-Z”
The basic capacitor is a pair of metal plates separated by an insulating material called the dielectric. The size of the plates, the type of dielectric, and the thickness of the dielectric determines the capacity. To increase capacity, you can increase the size of the plates, increase the number of plates, use a different dielectric or a thinner dielectric. The closer the plates, or the thinner the dielectric, the larger the capacity for a given size plate. Because flat plates are rather impractical, capacitors are generally made by putting and insulat ing m aterial (dielectric) between two foil strips and rolling the combination into a tight package or roll.
the capacitor is actually stored in the dielectric mater ial. When the capacitor is discharged, the electric di poles become re-oriented in a random fashion, discharg ing their stored energy.
CHARGED CAPACITOR
Fig. B — Applyin g a potentia l to a capacitor cause s th e dipoles in the dielectric to align with the applied
potential. When the capacitor discharges the dipoles \
ret urn to an unaligned, random or der.
UNCHARGED
CAPACITOR
When a capacitor is connected to a voltage source, it j does not become fully charged instantaneously, but takes a definite amount of time. The time required for the capacitor to charge is determined by the size or !.
capacity of the capacitor, and the resistor in series with j the capacitor or its own internal series resistance. This j is called the RC time constant. Capacity in Farads mul tiplied by resistance in Ohms equals the RC time con- j! stant in seconds. The curve of the charge of the capacitor v is the RC charge curve.
Fig . A — Many capacitors are made of foil separated by a dielectric and rol led int o a tight package.
The old explanation of how a capacitor works had the
electrons piling up on one plate forcing the electrons
off of the other to charge a capacitor. This made it
difficult to explain other actions of the capacitor. Fara day’s theory more closely approaches the way a capacitor really works. He stated that the charge is in the dielectric material and not on the plates of the capacitor. Inside the capacitors dielectric material,
there are tiny electric dipoles. When a voltage is applied
to the plates of the capacitor, the dipoles are stressed and forced to line up in rows creating stored energy in the dielectric. The dielectric has undergone a physical
change similar to that of soft iron when exposed to
current through an inductor when it becomes a magnet. If we were able to remove the dielectric of a charged capacitor, amd then measure the voltage on the plates of the capacitor, we would find no voltage. Reinserting the dielectric and then measuring the plates, we would find the voltage that the capacitor had been charged to before we had removed the dielectric. The charge of
100 j
---------
90 —------------------:
g0|— ;
40 I—T-------------------------------
30 I f
20 W
■t of--------------------------- -— ■
0I
---------
ORC 1RC 2RC 3RC 4RC 5RC
Fig. C — Capacitors follow an RC charge time as they
charge to the appli ed volta ge.
-----------
----
------------—..........
---------
---------------------
;— ^
-- - -- - ----- - -- - -- - -- - -
r= — at-u
;-----------;
--------
1-----------------------
----------------------------—----------------:---------------------
------------------------------------------------------------------:— -
----------—
;
------
------------ ----------- -----------
■
J
60
The “Auto-Z” makes use of this charge curve to measure the capacity of a capacitor. By applying a pulsating DC voltage to the capacitor under test and measuring the
time on its RC charge curve, the capacity of the
capacitor can be determined very accurately.
Capacitor Types
There are many different types of capacitors, using dif ferent types of dielectrics, each with its own best capa bility. When replacing capacitors, it is best to replace with a capacitor having not only the same capacity and tolerance, but the same type of dielectric and tempera ture characteristics as well. This will insure of con tinued performance equal to the original.
The capacitor is often named according to the type of dielectric which is used, such as paper, mylar, ceramic, mica or aluminum electrolytic.
Paper and mica were the standard dielectric materials used in capacitors for years. Ceramic became popular due to its stability and controlled characteristics and lower cost over mica. Today, there are many dielectrics with different ratings and uses in capacitors. Plastic films of polyester, polycarbonate, polystyrene, poly propylene, and polysulfone are used in many of the newer large value, small size capacitors. Each film has its own special characteristics and is chosen to be used in the circuit for this special feature. Some of the plastic films are also metalized by vacuum plating the film with a metal. These are generally called self-healing type capacitors and should not be replaced with any other type.
TEMP ER ATU RE *C
Fig. D — Te mpe rature change vers us capacity chang e of P100 to N750 t emperature compensated ceramic disc capacitors.
Ceramics
Ceramic dielectric is the most versatile of all. Many variations of capacity can be created by altering the
ceramic material. Capacitors that increase, stay the
same value, or decrease value with temperature
changes can be made. If a ceramic disc is marked with a letter P such as PI00, then the value of the capacitor will increase 100 parts per million per degree centig rade increase in temperature. If the capacitor is marked NPO or COG, then the value of capacity will remain constant with an increase in the temperature.
Ceramic disc capacitors marked with an N such as NI500 will decrease in capacity as the temperature
increases. The negative temperature coefficient is im portant in many circuits such as the tuned circuits of
the radio and television'IF. The temperature coefficient
of an inductor is positive and the inductance will in
crease as the temperature rises. If the tuning capacitor
across the coil is a negative coefficient, then the net
result will be a zero or very little change.
General type ceramic discs are often marked with such letters as Z5U, Z5F, Y5V, X5V, and so forth. This indi cates the type of temperature curve for the particular capacitor. Ceramic capacitors that are not NPO or rated with N or P type characteristics will have wider temper ature variations and can vary both positive and nega-
TE MP E RA TU R E ”C
Fig. E — Te mpe rature change versus capacity change
of N750 t o N5600 temperature compensat ed ceramic disc capcit ors.
tive with temperature changes. The Z5U probably has the greatest change and will only be found in non-crit- ical applications such as B + power supply decoupling. These type of capacitors should not be used in critical applications such as oscillator and timing circuits.
A ceramic capacitor marked GMV means that the value marked on the capacitor is the Guaranteed Minimum
Value of capacity at room temperature. The actual value of the capacitor can be much higher. This type
61
TEMPER AT UR E °C
STABLE TYPES
TE MPE R ATURE"C
TEMP ER AT U RE ‘ C
Fig, f — Temperature ch ang e versus capacit y change of non-temperature co mpensated ceramic disc ca pacitors.
of capacitor is used in bypass applications where the
SEMI-STABLE TYPES
G ENERAL P URPOSE TYPES
Tantalum Electrolytics
actual value of capacity is not critical.
The tantalum electrolytic capacitor is becoming very
Ceramic capacitors have been the most popular
capacitors in electronics because of the versatility of the different temperature coefficients and the cost. When replacing a ceramic disc capacitor, be sure to replace the defective capacitor with one having the
same characteristics and voltage rating.
popular. While the leakage in the aluminum lytic is very high due to the nature of its construction, leakage in tantalum capacitors is very low. In addition, tan talum capacitors can be constructed with much tighter tolerances than the aluminum lytic. The tantalum is much smaller in size for the same capacity and working voltage than an aluminum lytic. Tantalum lytics are popular in circuits where high capacity and low leakage
Aluminum Electrolytics
is required. The capacity and voltage rating of the tan talum lytic is limited, and for extremely large values
The aluminum electrolytic capacitor or “Lytic5’ is a very popular component. Large value capacity in a relatively
of capacity and higher voltages in power supply filter ing, the aluminum lytic is still the first choice.
small case with a fairly high voltage rating can be
obtained quite easily. The aluminum lytic is used in
power supply filtering, audio and video coupling and
in bypass applications. The aluminum lytic is made by using a pure aluminum
foil wound with a paper soaked in a liquid electrolyte. When a voltage is applied to the combination, a thin layer of oxide film forms on the pure aluminum forming
Cathode
Electrode
Diel e c tric
Oxide Laye r
Anode
El e c tr o d e
Conducting
Electrolyte
u b i 'o 'jO i 7 i'Tfo o ..V . Sot
the dielectric. As long as the electrolyte remains liquid, the capacitor is good or can be reformed after sitting for a while. When the electrolyte drys out the leakage goes up and the capacitor loses capacity. This can hap pen to aluminum lytics just sitting on the shelf. When an aluminum lytic starts drying out, the capacitor be
- S eries Re s istan ce
(Leads, Electrodes,
And Electrolyte)
= Leakage R esistance
Of Dielectric Film
gins to show dielectric absorption. Excessive ESR is
also a common failure condition for aluminum lytic
capacitors.
Fig. G — Con struction of an electrolytic cap acitor and its equivalent circuit.
62
A C apacitor Is More Than A Capacitor
An ideal capacitor is defined as “a device consisting of two electrodes, separated by a dielectric, for introducing capacitance into an electric circuit.” Unfortunately, we don't work with ideal components. The capacitors we encounter every day in. our service work are much more complex than this simple definition. In an actual capacitor, a certain amount of current leaks through the dielectric or the insulation. Capacitors have inter nal series resistances, can exhibit an effect called dielec tric absorption, and the capacitance can change in value. If we were to draw a circuit to represent an actual capacitor, it might look like the circuit in Figure H.
Capac it or
ous leakage paths through the dielectric. Thus, as the amount of water in the electrolyte decreases, the capacitor will be less capable of healing the leakage paths and the overall leakage current in the capacitor will ultimately increase. The increase in leakage cur rent will generate additional heat, which will speed up the chemical processes in the capacitor. This process, of course, will use up more water and the capacitor will eventually go into a run-away mode. At some point, the leakage current will finally get large enough to adversely affect the circuit the capacitor is used in.
Dielectric Absorption
One of the most common types of failures of electrolytic capacitors is dielectric absorption. Dielectric absorption
is the result of a capacitor remembering a charge that
is placed on it. The capacitor cannot be completely dis charged and a voltage will reappear after the capacitor
has been discharged. Another name for dielectric ab
sorption is battery effect. As this name implies, a capacitor with excessive dielectric absorption will act
like a battery in the circuit. This will upset the circuit
by changing bias levels. A capacitor with excessive dielectric absorption will also have a different effective capacitance when it is operating in a circuit. Dielectric
absorption will.not normally show up in film or ceramic capacitors, but if the “Auto-Z” test does indicate dielec tric absorption the capacitor is likely to fail in use. Dielectric absorption in these capacitors will generally be associated with a high leakage as well.
Fig. H — Equivale nt c ircuit of a pr actical capacito r.
The capacitor Cl represents the true capacitance, the resistance Rp represents the leakage path through the capacitor, and the resistance Rs5 called the Effective Series Resistance (ESR) represents all of the combined internal series resistances in the capacitor.
Leakage
One of the most common capacitor failures is caused by current leaking through the capacitor. Some capacitors will show a gradual increase in leakage, while others will change rapidly and even short out entirely. In order to effectively test a capacitor for leak
age, it is necessary to test the capacitor at its rated voltage.
When a DC voltage is applied to a capacitor, a certain
amount of current will flow through the capacitor. This
current is called the leakage current and is the result
of imperfections in the dielectric. Whenever this leak
age current flows through an electrolytic capacitor, nor mal chemical processes take place to repair the damage done by the current flow. Heat will be generated from the leakage current flowing through the capacitor and will speed up the chemical repair processes.
Cathode
Lead Resistance
Cathode Lead-To-Piate Resistance
Resistance Of Cathode Plate
Resistance Due To
Electrolyte
Resistance Of Anode Plate
A node L ead-Tfc-Plate Resistance
Anode Lead R esistance
As the capacitor ages, the amount of water remaining
in the electrolyte will decrease, and the capacitor will be less capable of healing the damage done by the vari
Fig. I— The Effective Series Resist ance (E SR) is com
posed of all the c ombined in ternal resistances in the
capacit or.
63
Equivalent Series Resistance
Another problem which develops in capacitors is high Equivalent Series Resistance (ESR). All capacitors have a certain amount of ESR. Sources that contribute to ESR include lead resistance, dissipation in the dielec tric material, and foil resistance. Small, non-electroly- tic capacitors should have extremely small amounts of ESR. An electrolytic capacitor which has excessive ESR will develop internal heat which greatly reduces the life of the capacitor. In addition, ESR changes the im
pedance of the capacitor in circuit since it has the same
effect as adding an external resistor in series with the component.
their capacitance due to the failure of the aluminum oxide film making up the dielectric. A change in value in an aluminum electrolytic will often also be preceded by other defects, such as high leakage, high dielectric absorption and/or high internal resistances.
Outer Coating
Ceramic Dielectric
Capacitor Plate
Craci<
(fissure)
Lead sofdered
to capacitor
plate
Fluctuating
AC
Fig. J — The Equivalent Series Resistance has the re sult of isolating t he capacitor from the power supply
lin e, reducing its filtering capabilities.
I
Capacitor
is olated
From Power Supply Line
Value Change
Fig. K — A ceramic disc is made of a silver coated
ceramic d ielectric which is coated with a protecti ve
coating. Large cracks or fissur es in the dielectric may develop whi ch change th e capacitance value.
As Figure L shows, the ESR is the combined resistances of the connecting leads, the electrode plates, the resis tance of the lead to plate connections, and the losses
associated with the dielectric. All capacitors have some ESR. Normal amounts of ESR are tolerated by the capacitor and the circuit it is used in. Defects can occur,
however, in the capacitor which will increase the ESR
in the capacitor. Any increase in ESR can affect the circuit in which the capacitor is used, as well as the capacitor itself.
Excessive ESR caused heat to build up within the capacitor, causing it to fail at an accelerating rate. ESR also reduces the ability of a capacitor to filter AC. As the model in Figure M shows, the series resistance RS
isolates the capacitor from the AC it is to filter.
Capacitors can change value. On some multi-layer foil capacitors, poor welding or soldering of the foil to the leads can cause an open to one of the foils to develop due to stress of voltage or temperature. This can result in a loss of almost one-half of the capacitor’s marked capacity. Ceramic disc capacitors can also change value
due to fissures or cracks. Small fissures or cracks in the ceramic insulating material can be created by ther m al, stress from exposure to heat and cold. Sometimes
very small fissures develop which do not effect the
capacitor until much later. The crack will reduce the
capacitor to a smaller value. Although the ceramic is
still connected to the leads, the actual value of capacity could be a very small portion of the original value de pending upon where the crack occurs. The “Auto-Z” w ill let you know what the value of the capacitor is
regardless of its marked value.
Electrolytic capacitors are another example of capacitors that can change value in circuit or on the shelf. As these capacitors dry out, they eventually lose
64
Color
Ra t e d
Vo lt a g e
Cap ac i
1st
Figur e
Picof
ta nce in
ar a ds
2nd
Fig u r e
Dipped Tantalum Capacitors
Mul ti pl ie r
Black 4
Brown
Red
O r a nge
Yellow
Gre e n
Blue
Violet
Gray
Wh it e
0 0
6
10
15 3 3
20
25 5 5 100 , 0 0 0
35
50
—
3 9
1
2
4
6
7 7
8
1
2
4 10,0 0 0
6 1,0 0 0 , 0 0 0
8
9
—
—
—
—
10 , 0 0 0 , 0 0 0
•
—
Ceramic Disc Capacitors
Manufactur er’s
Temperature
Code
Capacity
Vaiu e
Tolerance
*Worktng
Volta ge
Range
f
Low
Te m p.
+ 100 0
-30 ° C
-55 °C
Typical Ceramic Disc Capacitor Markings
Max, Cap a c.
Let te r
Sym b o l
High
Te mp.
Z + 45 °C Y + 6 5°C X + 85 ° C
+ 105 ° C + 12 5°C
Nume ric al
Symbol
2 4 5 6 7
Temperature Range Identification of
Ce ramic Disc Capacitors
C h ang e Over Tem p . Rang e
+ 1.0% A ± 1.5% B ± 1.1%
± 3.3 % D ± 4.7 % E
± 7.5% ± 1 0.0% P ± 15.0% ± 22.0 % S
+ 22 % , -33% + 22 % , -56% + 2 2% , -82%
If No Voltage Marked,
Generall y 500 VDC
Le t t e r
Sy m bol
C
F
R
T
U V
1st & 2nd
Fig. of
Capacita nce Multiplier
1
10
100
1,000
10,000
100,000
.01 8
.1
Nu merical
Sym b o l
0 1 2 3 4 5
—
9
To l e r a n c e on
Capacita nce
± 5 % J ± 10% K ± 20%
+ 100%,-0 % P + 8 0 %, -20%
Capacity Vaiue and Toleran ce of
Ceramic Disc Capacitors
Lette r
Symb o l
M
Z
65
Film Type Capacitors
Ceramic Feed Through Capacitors
f irs t d igit
OF VALUE
SECOND DIGIT OF VALUE
MULTIPLIE R
MULTIPLIER
For t he
Nu mbe r Mul tip li er Lette r
0
1 10 C
2
100 D ± 0.5 pF
3 1,000 4
10 , 000 G ± 2.0 pF ± 2%
TOLERANCE OF CAPACITOR
10 pF or L es s
1
B
± 0.1 pF ± .25 pF
F
± 1.0 pF ± 1 %
5 100,000 H
J
8 0.01 K
9 0.1 M
EXAMPLES:
152K = 1 5x 1 00 = 1 5 00 pF or.001 5u F, ±10% 75 9J = 75x0.1 = 7.5 pF, ±5 %
Over 10 pF
± 3% ± 5%
±10%
±20%
Multiplier
Significant J 1st figure \ 2nd
Signifi-
can t
Color
Blac k Brow n
Red 2
Or ange 3 1,000
Yellow
Gr e en
Blue
Violet
Gray 8 W h it e 9 0.1
Gold Silve r
Figure Mult ipU er
0 1 2 pF 20% 0 1 10 0.1 p F 1%
100
4 10 ,0 0 0 5
6 7
_ —
—
_
—
0.001 0. 0 2 5 p F
_
—
To leran c e
10 pF
or L e s s
_
—
_
5 pF 5%
_ — —
1 pF 10%
_
—
Tolerance
Temperature coefficient
Over
10 pF
N30
2% N60
2.5% N150
_
N220 N330
_
N470 N750
—
P30
+ 120 t o -750
(RETMA)
+ 500 t o -330 (JAN)
_
P100
—
By pass or coup l i ng
Tempera t ure
Coe f fic i en t
NOTE: Th e l e t t e r “ R” m a y b e u s ed at times to sig ni fy a deci mal poi n t; as in: 2R2 = 2.2 (pF o r uF).
Postage Stamp Mica Capacitors
Mica capacitors-Black {AWS paper capacitors-^ silver)
. t
Characteristic
AWS and JAM fixed capacitors
(First d o t silv er or black}
First
significant figure
Second significant figure
First
significant figure
(No t silv er
or bla ck) .—
Voltage rating
-------
0> 0> o
^ ^ 0, ] significant figure
O O O
First
___significant figure | [— Second
significant figu re
0>
O*0
*
I— Decimal mu l ti p lier
1— Tolerance
Decimal multiplier
Second significant figure
----
Third
I— Decimal multiplier
— Tolerance
Col o r
Black Brown
Red 2 Orange 3 1,000 Yellow
Green 5
Blue 6
Violet
Gray 8
White 9
Gold
Silver
No color
Sig n if ic a n t
Figure M u lt i p li e r
0
1
4
7
1,000,000,000 9
-
-
—
10 1 100
100 2 200
. . 10,000
100,000 5
. 1,000,000 6
10,000,000 7 700
100,000,000 8 800
0.1
0.01 10 —
Tolerance
{%}
_
1
3 4
5 1000
20 500
Volta g e
Ra t i n g
—
300 400 500 600
900
2000
66
Standard Button Mica
1s t DOT
ide n ti f ie r
2nd a nd 3rd DOTS 4 th DOT
Capacita n ce in pF Multip lier
1 st & 2nd
Sig. Fi g s . Perce nt
0
■■ 1 2
3
4
5 6
7 8
9 0.1
Black Black
NOTE: Ident ifier is omi tted if
capacitance
mus t be
specifie d to
three
signif ica nt
figures.
Color
Brown Red
Orange YeSiow
Green Blue
Violet Gray
White Gold
Silver
Radiai or Ayial Lead Ceramic Capacitors
(6 Dot or Band System)
s *
Eit h e r type lea d
1
10
100 1000
5th DOT
Ca pac i t a nce
To l e r a n c e
±20%
± 1%
s:2% or ±TpF
± 3%
±5 % ■■■ J
± 10%
5 Dot or Band Ceramic Capacitors
Temperature coefficient
Lette r
Symb ol
F F
GorB
H
K
6th DOT
Temp.
C har a cter i s t ic
+ 100
-20 PPM/° C
above 50 pF
±1 00 PPM/°C
below 50 pF
(one wide band)
_ A-First significant figure
— B -S e c on d s i g n if i c a n t figur e
— C-Decima! multiplier
f D-Capacitance tolerance
* \
-I
wk — m
Temp. Coefficient Capacitance
T.C.
P100 P030
NPO N030
N080 N150
N220 N330
N470 Blue N750
N1500 N2200
N3300 N4200
N4700 Orange N5600
N330
±500 White
N750
± 1000
N3300
±2500
1st
Color
Red Green
Black Brown
Red Orange
Yellow Green
Violet Orange
Yeliow Green
Green
Green
Gray
Gray Biac k
2nd
Color
Violet
Blue
Orange Orange
Orange Green
Black
__
Isl a n d
2nd Sig.
Fij.
0
1
2 100
3
4
5 6
7
8 9
Multi
plier Color
Black
1
Brown
10
Red Orange
1,000
Yeliow
10,000
Green Blue
Violet
.01
Gray
.1 Wh ite
DOTS OR
BANDS
Nominal C ap ac ita nc e
Tolerance
10 pF
or Less
± 2 .0 dF
± 0.1 pF
±0.5 pF
±0.25 pF +80%- 20%
± 1.0 pr ±10% White
Over 10 pF Cofor
±20 %
■ ± 1%
± 2% Red ± 3%
-f 100%-0? ± 5%
Biack Brown
Orange Yellow
Green Blue
Violet
Gray
Color
Biack
Brown
Red
Orange
Yeliow
Green
Blue Violet
Gray White
Fixed cermic capacitors, 5 dot or band system
Color Code fo r Ceram i c Capacitors
Capacita nce
1s t & 2nd
Si g n i f i c a nt
Figure
Mult ip lie r
0
1
2
O
w
A
100
1000
5
6
7
8
0.01
9 0.1 ± 10%
110± 20 %
To le r a n c e
Over
10 pF
± 1%
± 2%
± 5 %
10 pF
or Le s s
2.0 pF
0.5 pF N 47 0
0.25 pF P 30
1.0 pF P500
Te mp. Coeff .
0
N30
N80
N15 0
N220 N330
N75 0
67
5 Band Ceramic Capacitors
(all ba nds equal size)
j j II |j .
color
1st, 2nd Band
Black Brown
Red
Orange Yellow
Green
Biue
Violet Grey
White 9 Gold
- -
Silver
Mil Spec, indent. Tolerance
1st Fig
Mult
2nd Fig.
Multiplier
0 1 1
2
100 Y5T
10
Tolerance
±20% (M)
3 1K 4
5
10K
N330
6 7
8
±30% ( N)
SL(GP)
0.1 ±5% (J) Y5F
-
0.01 ±10%(K) Y5P
Tubular Encapsulated RF Chokes
Characteristic
1
v /j w j j j u u h l
W
i / ) H / ITT T FY i1T7
.....
ZZZZZZZZZZZZZZZ5
NPO
Y5S
N150 N220
N470 N750
Y5 R
Back
Co/or Figure Multiplier
Black
Brown
Red
O r a nge 3
Yellow
Gr e e n
Blue
Violet
Gray
Wh it e
Non e
Silver
Gold
Multiplie r is the fact o r by whic h the two colo r figures are mu l t i p l ied t o obtain the induc ta n ce value of the chok e coi l in uH.
Values will be in uH.
0
1 1-0
2 100
4
5
6
7
8
9
1
1,000
Tolerance
20%
10%
5%
‘POS TAGE STAM P” FIXED INDUCTORS
1st Digit 2nd Digit
Colo r
Black or (Blank)
Brown
Red
O r a n ge 3 3 1,0 0 0
Yeliow
Gr e e n 5
Biue
Violet
Gray
Whit e 9
Gold
Stiver
1st S tr ip 2 nd Str ip
0
1 1 1 °
2 2
4 4 10,00 0
6 6
7
8
0 1
5 10 0 , 0 0 0
Mu lt ip l ie r
3rd S t r i p
100
7
8
9
X.1
X.01
68
69
S3JL0N
GLOSSARY
Aging — operating a component or instrument at con trolled conditions for time and temperature to screen out weak or defective units and, at the same time, stabilize the good units.
Anode — the positive electrode of a capacitor or diode. Capacitance — the measure of the size of a capacitor.
Usually expressed in microfarads and picofarads. De termined by the size of the plates, and the dielectric material.
Capacitive reactance — the opposition to the flow of
a pulsating DC voltage or AC voltage. Measured in
ohms.
Capacitor — an electronic component consisting of two metal plates separated by a dielectric. Can store
and release electrical energy, block the flow of DC cur rent or filter out or bypass AC currents.
Cathode — the negative electrode of a capacitor or
diode.
Charge — the quantity of electrical energy stored or held in a capacitor.
Clearing — the removal of a flaw or weak spot in the dielectric of a metalized capacitor. The stored energy in the capacitor vaporizes the material in the im mediate vicinity of the flaw. Also called self-healing or
self-clearing.
COG — same as NPO. Very small capacity charge for
large temperature changes.
Coil — an inductor wound in a spiral or circular fash ion. Can be wound on a form or without a form such
as an air coil.
CV p roduct — the capacitance of a capacitor multip
lied by its working voltage. Used when determining
the leakage allowable in electrolytic capacitors. The
CV product is also equal to the charge that a capacitor
can store at its maximum voltage.
Dielectric — the insulating or non-conducting mater
ial between the plates of a capacitor where the electric
charge is stored. Typical dielectrics include air, impre
gnated paper, plastic films, oil, mica, and ceramic.
Dielectric absorption — the measure of the inability
of a capacitor to completely discharge. The charge that
remains after a determined discharge time is expressed
in a percentage of the original charge. Also called
“Capacitor Memory” or “Battery Action”.
Dielectric constan t — the ratio of capacitance be tween a capacitor having a dry air dielectric $nd the ; given material. A figure for determining the efficiency of a given dielectric material. The larger the dielectric constant, the greater the capacity with a given size plate.
Disc capacitor — small single layer ceramic capacitor
consisting of disc of ceramic dielectric with silver depo sited on both sides as the plate. The ceramic material can be of different compositions to give different tem
perature curves to the capacitor. Dissipation factor (BF) — the ratio of the effective
series resistance of a capacitor compared to its reac
tance at a given frequency, generally given in percent.
Electrolyte — a current conducting liquid or solid be tween the plates or electrodes of a capacitor with at least one of the plates having an oxide or dielectric film.
I
Electrolytic capacitor (aluminum) — a capacitor consisting of two conducting electrodes of pure
aluminum, the anode having an oxide film which acts
as the dielectric. The electrolyte separates the plates.
Equivalent series resistance (ESR) — All internal
series resistances of a capacitor are lumped into one resistor and treated as one resistor at one point in the
capacitor.
Farad — the measure or unit of capacity. Too large
for electronic use and is generally measured in micro
farads or picofarads.
Fissures — cracks-in the ceramic dielectric material
of disc capacitor, most often caused by therm al shock.
Some small fissures may not cause failure for a period
of time until exposed to great thermal shock or mechan
ical vibration for a period of time.
Fixed cap acitor — a capacitor designed with a specific
value of capacitance that cannot be changed.
Gimmick — a capacitor formed by two wires or other conducting materials twisted together or brought into close proximity of each other.
GMV — Guaranteed Minimum Value. The smallest value this ceramic capacitor will have. Its value could be much higher.
Henry — The unit of the measure of inductance. Also expressed in microhenry and millihenry.
Inductor — a device consisting of one or more windings with or without a magnetic material core or introducing inductance into a circuit.
70
Inductance — the property of a coil or transformer which induces .an electromagnetic force in that circuit or a neighboring circuit upon application of an alternat
ing current.
Inductive reactance — the opposition of an inductor to an alternating or pulsating current.
Impedance — the total opposition of a circuit to the flow of an alternating or pulsating current.
Insulation resistance — the ratio of the DC working voltage and the resulting leakage current through the dielectric. Generally a minimum value is specified, usu ally in the several thousand megohms range.
Iron core — the central portion of a coil or transformer. Can be a powdered iron core as in small coils used in RF to the large iron sheets used in power transformers.
Leakage current — stray direct current flowing through the dielectric or around it in a capacitor when a voltage is applied to its terminals.
Metalized capacitor — one in which a thin film, of metal has been vacuum plated on the dielectric. When a breakdown occurs, the metal film around it im mediately burns away. Sometimes called a self-healing capacitor.
Temperature coefficient (TC) — the changes in cap acity per degree change in temperature. It can be posi tive, negative, or zero. Expressed in parts per million per degree centigrade for linear types. For non-linear types, it is expressed as a percent of room temperature.
Time constant — the number of seconds required for
a capacitor to reach 63.2% of its full charge after a voltage is applied. The time constant is the capacity in farads times the resistance in ohms is equal to seconds
(T=RC). Trimmer — a low value variable capacitor placed in
parallel with a fixed capacitor of higher value so that the total capacity of the circuit may be adjusted to a given value.
Variable capacitor — a capacitor that can be changed in value by varying the distance between the plates or the useful area of its plates.
Voltage rating — see working voltage. Wet (slug) tantalum capacitor — an electrolytic
capacitor having a liquid cathode. Working voltage — the maximum DC voltage that
can be applied to a capacitor for continuous operation at the maximum rated temperature.
Monolithic ceramic capacitor — a small capacitor made up of several layers of ceramic dielectric sepa rated by precious metal electrodes.
Mutual inductance — the common property of two inductors whereby the induced voltage from one is in duced into the other. The magnitude is dependent upon the spacing.
NPO — an ultra stable temperature coefficient in a ceramic disc capacitor. Derived from “negative-posi- tive-zero”. Does not change capacity with temperature changes.
Padder — a high capacity variable capacitor placed in series with a fixed capacitor to vary the total capacity of the circuit by a small amount.
Power factor — the ratio of the effective resistance of a capacitor to its impedance.
Reactance — the opposition of a capacitor or inductor to the flow of an AC current or a pulsating DC current.
Self-healing — term used with metalized foil capacitors.
Solid tantalum capacitor — an electrolytic capacitor
with a solid tantalum electrolyte instead of a liquid.
Also called a solid electrolyte tantalum capacitor. Surge voltage — the maximum safe voltage in peaks
to which a capacitor can be subjected to and remain within the operating specifications. This is not the working voltage of the capacitor.
71
NOTES
72
SERVICE & WARRANTY
Warranty
Your Sencore inst r u ment h as b e en buil t to the hi g hest quality st andards in the indu st r y. E a c h un i t h as b e en test ed , aged und e r power for at l e a st 24 hours , an d then r ete s t ed on ever y f u nc ti o n a n d ra ng e to i nsur e it me t all pub l i she d sp ecif i cati ons after agi ng. Your i n s tr u ment is fu lly po r t ect e d with a 1 ye a r wa rr an t y and S e n c o r e’s exc l u si v e 100 % M a d e Right Lifet im e Guara ntee In t he uniikeiy event a m anufa c tur i ng d efec t is m i s sed by th es e t es ts. Detail s ar e c o v e r e d in the s epara t e b o o k l e t. Read this b o o klet th or o ug h ly , an d kee p it in a s afe p ia c e so you can r ev iew it if q uestions ari s e later.
S er v i c e
The Sen c o re Factory Service De p a r tment pr ovides all in or out-of-warranty se rv i ce and co mp lete recalibration servic es for Se n c o r e instruments. NO LOCAL SERVICE CENTERS ARE AUTHORIZED TO REPAIR SENCORE INSTRUMENTS. Factory servic e a ssures you of the highest quality work, the late s t cir cu it impro vem ents, and t h e fas te s t turna r o u n d time poss ib le becaus e every techn icia n sp e c ia l iz e s in Sen co re inst ru m en ts . Se n co r e’s Se rv ic e Dep ar tment can usually repair your in s t r u ment an d return it to you faster than a local facility
servicing ma ny b r a n ds of instru m en ts , ev en wh e n shipping time is included.
YOU DO NOT NEED AUTHORIZATION TO RETURN AN INSTRUMENT TO SENCORE FOR SERVICE. Be sur e you inclu de your n am e a n d addr es s along with a description of t he s y m p to ms if it should ever b e nec e s sary to retur n your instrume nt. Ship your in s tr u ment by United Parcel Service or airfreight if possible . Us e parcel post only when abso lu te ly n e c e ss a ry .
BE SURE THE INSTRUMENT IS PROPERLY PACKED. Use the original shipp ing car to n an d all packi ng inserts wh en ev er p o ss ib le . If th e
original packin g material is not avail able , m a ke cer tai n the unit is properly packe d in a sturdy box with shock-ab sorbi ng materia! on all
sides. Sen c ore su g gest s insuring th e inst ru ment for its full value in cas e it is lost or da mag e d in sh ipm en t.
A sep ar a te sch e m a t ic and par ts list is in c lu d ed if you wish to r ep ai r your own i n s tr u ment . Part s may be ordered directly from the Factory
Service Departmen t. Any p a rts no t shown in the parts list may b e ordered b y descrip t ion . Mai nte na nce instructions an d circuit descriptions may be ordered from th e Service Par ts D e p ar tm e n t
We reserve t h e right to examine defec ti v e c o mpone n t s before an in-warranty r e plac e men t is issued.
SENCORE FACTORY SERVICE 3200 Se n co r e Drive Sioux Falls, SD 57107 (605)339-0100 TWX: 910-660-0300
Fill In f or yo yr re cor ds:
Date Purchased:
Serial Nu m be r
Run Number_______________________
(NOTE: Please refer to the run n u m be r if it is necessary to call the Service Department. The run num ber may be updat ed
when the unit has been return ed f or service.)
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ELECTRONIC TEST EQUIPMENT
Innovatively DesignedWith Your.Time In Mind . 3200 Sencore Drive
Sioux Falls; Soutn Dakota 57107 v
(6 05 ) 339-0100
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