Tektronix 1920 Instruction Manual
INSTKUCTIW MANUAL
IlUUEL 1YZU
TKWS UPTIUII
Copyright 1981 Keithley Instruments, Inc.
First Printing, July, 1981, Cleveland, Ohio, U.S.A.
Document No. 32000, Kev. A
Table of Contents
Section
ClENEKAL INFORMATION
1.
l-l.
l-3. Warranty Information.
1-5.
l-7. Safety Symbols and Terms.
l-9. Specifications.
2.
OPERATING INSTRUCTIONS.
2-l.
2-4. Operation in Model 192.
3.
MAINTENANCE .................................
3-2. Installation in Model 191
3-3. Installation in Model 192
3-4.
3-6. Kecommended Test Equipment.
3-7.
3-9.
3-11.
3-13. Calibration
3-15. Kecommended Test Equipment.
3-17. Environmental Conditions.
X-19.
3-22. Troubleshooting
3-24. Troubleshootiny Procedure
Introduction.
Manual Addendums.
Operation in Model 191.
Performance Verification.
Environmental Conditions.
Performance Verification Procedure.
Initial Conditions.
Calibration Procedure
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Page
l-l
l-l
l-l
l-l
l-l
l-l
2-1
2-l
2-1
3-l
3-l
3-2
3-3
3-3
3-3
3-3
3-4
3-6
3-6
3-G
3-6
3-9
3-9
4.
TtiEURY OF UPEKATIUN
REPLACEABLE PAKTS
5.
5-l.
5-3. Ordering Information.
5-5.
5-7.
General
Factory Service
Schematic and Component Layout.
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4-l
5-l
5-l
5-l
5-i
5-l
Model 1920
l-l. INTRODUCTION
General Information
SECTION 1. GENERAL INFORMATION
l-2.
Models
siynal.
Model
installable.
1-3.
l-4.
to exercise the Warranty,
the proper action to be taken.
facilities in the United States, West tiermany,
Switzerland and Austria.
your instrument may be directed to the applications engineer at any of the above
locations.
l-5. Manual Addendums
1-G.
will be explained on an addendum which will be attached to the inside back cover.
The Keithley Model
192
and
191.
When the 1920 is installed in the Model
1920
has four ranges on which an AC siynal can be measured.
Warranty Information
The warranty is yiven on the inside front cover of this manual. If there is a need
Check the inside front cover of this manual for addresses.
Improvements or changes to the instrument that occur after printing of the [manual
1920
is a True Root Mean Square (TKMS) AC plug-in option for the
The 1920 enables the 191 or 192 to measure the TKMS value of an AC
192
an ACtUC function is available. The
It
is field
contact the Keithley Representative in your area to determine
Keithley maintains complete repair and calibration
tireat Britain, France, the Netherlands,
Information concerning the application, operation or service of
1-7.
l-8. The symbol
instructions.
The symbol
The WARNING used in this manual explains dangers that could result in personal injury
or death.
The CAUTION used in this manual explains hazards that could damage the instrument.
l-9.
l-10.
Safety Symbols and Terms
A
on the instrument denotes that the user should refer to the operating
t
Specifications
Uetailed specifications for the Model 1920 are given in Table
on the instrument denotes that up to 5UllV may be present on the terminals.
l-l.
l-l
General Information
Model 1920
TABLE 1-l
1920 Specifications
5-l/2 Digit Accuracy, +(% Rdg + Counts),
5-l/2 Digit
Range
2v 1OPV 1% t
2ov lOOld
2oov 1mV 1% t
7oov 1OmV
RESPONSE:
CREST FACTOR
AC + DC MODE:
riAxIriuri INPUT:
SETTLING TIME:
INPUT IMPEDANCE:
TEMP. COEFFICIENT:
3dB BANTMIDTH:
CFIRR:
RESOLUTION
TRUE RFlS
Add 60 counts to specified accuracy (not wailable in We1
1OOOV Peak AC + DC, 2 x lo7 V* Hz
0.5 set to within 0.1% of change in reading
211 ohm shunted by less than 5OpF.
(O"-18OC and 28"-5O'C): Less than
specification per "C below 50kHz; 0.2 x for 50kHz to 1OOkHz
500kHz Typical
Greater than 60dB at 50 and 60Hz
20-50Hz"
1% t 100
1% t 100
100
100
1
yr 18-28'C
DC, 50Hz-lOkHz* lOK-20kHz"
0.25% t 100 0.35% + 300
0.25% t 100 0.35% + 300
0.25% + 100 0.35% + 300 1% t 500
0.354: t 100 0.5% + 300
0.1
x applicable accuracy
(lk
ohm unbalanced)
20kHz-lOOkHz**
1% t 500
1% t 500
1% t 500
191)
* Above 2000 counts
** Above 20000 counts; 3% + 500 typical below 20000
l-2
Model 1920
Operating Instructions
SECTION 2. OPERATING INSTRUCTIONS
Z-l. Operating Instructions for the rlcdel 1920 installed in the ilodel 191 are as
follows:
2-2.
to 1000v.
voltage.
2-3.
Ilith the ilodel 1920 option, the ilcdel 191
The instrument displays the True Koot llean Square (TKilS) value of an AC
It has a frequency response of 20Hz to 100ktlz.
The rnaximm reading is 199YYY. Werrange is irdicatcd by (-) l-----, except on
the 1000 volt range.
The 700 volt range is selected idith the 1000 volt button. On the
reads AC voltages froln 10 r;licrovolts/digit
700 volt range, the display can read beyond the rnaxiinuln allobiable input voltage. ilaximun
allobcable input: 1OOOV Peak AC + DC; 2 x lo7 V'Hz. Use the ilodel 191 to lneasure AC
voltage as follobis:
CAUTION
Do not exceed maximum allohcable input voltage. Instrument damage may
occur.
A. Turn the pokier on IJith the UN/OFF pushbutton,
Select the desired range from the 4 ranges available.
8.
ati depress the ACV pushbutton.
The decimal point is positioned
by the range pushbutton.
Ensure that the I0JLL pushbutton is out (light off) unless measurements are to be made
C.
as deviations from a preset value.
NOTE
Do not use NULL to zero the range.
A small residual zero readirq is
normal. If NULL is used to zero this offset, readings in specified
accuracy range will be low by the offset amount.
This is because rms
measurement signals add in a root mean square fashion arrl not
linearly.
The NULL function is a linear offset axl not usable in TKllS
measurements.
Connect the signal to be measured between the INPUT HI ati LO binjiny posts. The
0.
birding posts accept wires, spade lugs or banana plugs for ease of connectiq the
circuit to be measured.
Observe the displayed digits ard decimal point.
2-1
Operating Instructions
E.
For specified accuracy (pulse widths ,lOns, peak voltage (1.5 x full scale) Figure 2-1
shows the allowable input signal vs. crest factor.
crest factor of three the displayed reading must be less than 100,000 counts (1V on
the 2V range).
crest factors exceeding that shown in Figure2-I, but accuracy will slowly degrade (For
CF >3 but<10 typical accuracy is degraded by (CF-3) x 0.36% arti peak signal must be
less than 5 x full scale for that range).
So long as the maximum input is not exceeded no damage will result in
CF
The figure illustrates that for a
Model 1920
I
0
Displayed Counts
Figure 2-l.
2-4. Operating Instructions for the Model lY20 installed in the Model 192 are as
follows:
2-5.
to 1ooov.
signal.
2-G.
input is 1OOOV Peak AC f DC; 2 x 107V.Hz. Use the Model
voltages as follows:
With the Model 1920 option, the Model
The instrument displays the True Koot Mean Square (TKMS) value of an AC voltage
The maximum reading is 199999.
Do not exceed maximum allowable input voltage. Instrument darnage may
occur.
Crest Factor VS. Displayed Counts
100000
192
reads AC voltages from 1 microvolt/digit
Overrange is indicated by OFLO. Maximum allowable
CAUTION
I
200000
192
to measure AC or AC + DC
A. TURN POWER UN with UN/OFF pushbutton.
B.
Press the ACV button once to select the ACV (TKMS) function. Press the ACV button
ayain and the 192 will measure the T'KMS value of an AC + UC signal (AC signal
superimposed with a DC level). The ACV and DCV LEDs will light simultaneously when
the AC + UC function is enabled.
the ACV function. Pressiny the DC button while in AC t DC returns the
function.
Pressing the ACV button again will return the 192 to
192
the DCV
2-2
UPEKATINti INSTKUCTIUNS
IWDEL 1YZU
NOTE
The 14odel 192 will display "NO AC" if ACV is selected without the 1920
or 1910 ACV option.
The AC + UC function is available only with C-4
and dbove software and Kev U and above Analoy Board.
C. SELECT KANtiE from the four ranyes available. The decimal point is positioned by the
ranye pushbutton. The 1UOUV ranye is selected with the 2000 button. If the ZUIQ
button is inadvertently pressed when in ACV function,
the 192 will set the ranye to
1uuo.
Il. ZEKU OFF unless [measurements are to be made as deviations frown a preset value.
NOTE
Uo not use ZEKU to zero the ranye. A small residual zero readiny is
normal. If LEKU is used, the residual voltaye readiny in specified
accuracy ranye will be low by the amplitude of the zeroed residual
voltaye.
This is because rms measurement signals add in a root mean
square fashion and NUT linearly. THe LEKU function is a linear offset
and not usable in TKMS measurelnents.
CONNECT IllPUT to be measured between the HI HCV and LO bindiny posts.
E.
F.
TAKE KEAUING.
ti. For specified accuracy (pulse widths LlUus, peak voltage (1.5 x full scale) Figure Z-l
shows the allowable input siynal vs. crest factor.
The figure illustrates that for d
crest factor of three the displayed readiny (must be less than lUU,UUU counts (1V on
the ZV ranye).
crest factors exceediny that shown in Fiyure 2-1,
So long as the maximum input is not exceeded no damage will result in
but accuracy will slowly degrade
(For CF >3 but 510 typical accuracy is degraded by (CF-3) x U.3GX and peak signal must
be less than 5 x full scale for that range).
Model 1920
SECTION 3. MAINTENANCE
3-l. The Model 1920 is a plug-in option that can be installed in your Model 191 or 192
Instdllation of the 1920 into your instrument is as follows.
WARNING
All service information is intended for qualified electronic maintenance
personnel only.
Maintenance
3-2. INSTALLATION: (For use with Model
A. Disconnect the line power cord of the Model
input terminals for safety.
B. Turn the DMM bottom side up and loosen the four screws in the bottom cover.
Hold the top and bottom cover together to prevent their separation and turn the DMM
C.
over to the normal position. Remove the top cover.
D. Remove the RF shield by grasping it and FIRMLY lifting it away from the motherboard.
E. Carefully insert the connector of the
motherboard. Take note of the orientation of the
shown in the figure below. Connect the brown wire of the
switch, and connect the blue wire to Pin 9 of the ACV switch.
F. Replace the RF shield being careful not to pinch any wires.
G. Calibrate the
1920
per the procedure located on Table 3-5.
191)
1920
191
and remove all test leads from its
into its mating receptacle on the 191
1920
into the 191 motherboard as
1920
to Pin 7 of the DCV
Replace the top cover.
H.
3-l
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