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Omega 873 Service and user manual

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r\: OMEGA
^^ ^^H FiyniiyFFDii\iG iiur
EIMGIIMEERIIMCIIMC.
In 0>lf."f» t lirwup Company
MODEL 873 Hand Held Digital
Thermometer
Operator's Manual
TABLE OF CONTENTS
GENERAL INFORMATION 1
Unpacking and Inspection 1 Optional Accessories 2 Preparation for Use 3 Safety Symbols Environmental Conditions 4
OPERATION 5
Safety Precautions 6
SERVICING INFORMATION 9
Functionality Check 9 Performance Verification 9 Environmental Conditions 10 Disassembly Instructions 10 Battery Installation/Replacement 12 Calibration 13
Probe Matching 15 Troubleshooting ...: 15 Special Handling of Static Sensitive Devices 18 Component Layout 21 Schematic Diagram 23
and
Terms 4
GENERAL INFORMATION
The OI^EGA® IVIodels 873C and 873F are Hand Held Digital Thermo­meters. Both instruments have large easy to read liquid crystal displays (LCD).
The input connection consists of a subminiature, type K thermo­couple, female connector (SMP-K-F). This input accommodates any OMEGA type K thermocouple probe fitted with an SMP-K-M connec­tor. Cold junction electronic circuitry compensates for ambient temperature changes. These instruments also provide piece-wise linearization conformity for thermocouple non­linearity. The instruments are powered by a 9V battery. Continuous operation of 350 hours is typical with an alkaline battery or 200 hours typical with a carbon-zinc battery.
The Model 873C measures temperature from - 55°C to 1000°C on
two ranges. The 200°C range measures temperature from -55.0°C to
199.9°C with a resolution of 0.1°C. The 1000°C range measures temperature from -55°C to 1000°C with a resolution of 1°C. The ac­curacy is ± (0.25% rdg of rdg -l-2°C) for -40°C to -55°C.
-i-
1.0°C)
in
the 873F/873C automatically
from -40°C to 1000°C and ± (0.25%
The Model 873F measures temperature from - 60°F to 200°F
ranges. The 200°F range measures temperature from -60.0°F to
199.9°F with a resolution of 0.1°F. The 2000°F range measures temperature from -60°F to 1999°F with a resolution of 1°F. The ac­curacy of the Model 873°F is ±(0.25% of rdg -i-2.0°F).
UNPACKING AND INSPECTION
Remove the Packing List and verify that all equipment has been received. OMEGA Customer Service Department at (203) 359-1660.
Upon receipt of shipment, inspect the container and equipment for
any signs of damage. Take particular note of any evidence of rough
handling in transit. Immediately report any damage to the shipping agent.
If there are any questions about the shipment, please call
NOTE
The carrier will not honor any claims unless all shipping material is saved for their removing contents, save packing material and carton in the event reshipment is necessary.
examination.
After examining and
on
two
ENVIRONMENTAL CONDITIONS
Operation of the Models 873C and 873F should take place at
bient temperature of -10°C to 50°C (14°F to 122°F), less than 80% relative humidity up to 35°C, lineariy derate 3%
60°C.
R.H./C
an
am-
from 35°C to
OPERATION
The 873C and 873F Hand Held Digital Thermometers are easy to use There is only one control (located on the side of the instrument) that turns the instrument on/off and selects the range. (See Figures 1 and
2).
Use the following procedure to operate the instrument:
1.
Turn on the power to the instrument by selecting the desired range.
Model 873C: A. 200°C range is the center position of the ON/OFF range switch. B. 1000°C range is the upper position of the ON/OFF range switch.
Model 873F:
A. 200°F range is the center position of the ON/OFF range switch.
B. 2000°F range is the upper position of the ON/OFF range switch.
2.
Select the appropriate temperature probe and insert it into the input
jack.
3. Make the measurement: A. Touch the probe tip to the material to be measured.
B. Read the display. The reading is in Celsius for the Model 873C.
The reading is in Fahrenheit for the Model 873F.
NOTE
An open sensor or overrange condition is indicated by:
CAUTION Do not attempt to measure temperatures beyond the range of the probe being used. Probe damage may occur.
WARNING
A shock hazard exists on the Models 8730 and 873F Input jacks when probes
or
sensors are exposed
to
voltage levels greater than 42V peak to earth ground.
SAFETY PRECAUTIONS
1.
Do not touch the probe tip when measuring excessively high or low
temperature.
2.
Do not exceed 42V peak from the probe tip or input jack to earth
ground.
Miniature TC Connector
OMEGA 873C THERMOMETER
Low Battery Indicator
LO
Minus Sign Displayed
Plus Sign Implied
•
BAT
-loao
3V4 Digit Display—
On/Off Range Switch
Figure 1. Model 873C Control Layout
200
TYPE K THEHMOCOUPLE
NiCr-N<AI
RANOE:
-IB'C
to
^ 42V MAX
4
lOOO'C
-^
Miniature TC Connector
Low Battery Indicator^
Minus Sign Displayed-
Plus Sign Implied
VA Digit Display-
On/Off Range Switch
OMEGA 873F THEHMOMETER
r DM I
-\QO.U
^=
TYPE K THEIIMOCOUPI.E
NiCr-NiAl
RANOE.
-tO'E
to
A 42V MAX
2000*F
+
^
Figure 2. Model 873F Control Layout
SERVICING INFORMATION
This section contains information needed to maintain the Models
873C and 873R The following information is included: functional
check, performance verification, disassembly instructions, battery in-
stallation/replacement, calibration, probe matching, troubleshooting, parts list, schematic diagram and component layout.
WARNING The information presented in this section is in­tended for use by qualified personnel only. Turn off the power and remove all probes from the instru-
ment before replacing the battery.
FUNCTIONALITY CHECK
At room temperature hold the tip of a probe sensor between your
thumb and index finger. A reading between 25°C and 40°C (77°F and
104°F) should be observed to confirm functionality of the instrument.
PERFORMANCE VERIFICATION
Accuracy Check
1.
Prepare a distilled water ice bath or use an OMEGA* TRC III Ice
Point Reference Chamber.
2.
Connect a TC probe to the input jack of the instrument.
3. Immerse the TC probe into the TRC III or distilled water ice bath and allow 10 minutes for thermal stabilization,
4.
Turn on the instrument and use Table 1 to verify that the readings
on each range are within specifications.
Table 1. Performance Verification
Range
200
1000
2000
873°C
0.0 ± 1°C
0 ± 1°C
873°F
32,0 ± 2°F
32 ± 2°F
ENVIRONMENTAL CONDITIONS
The Models 873C and 873F should be at an ambient temperature of
23°C ±1°C and a relative humidity of less than 80%.
DISASSEMBLY INSTRUCTIONS
Turn off the instrument and disconnect the temperature probe before removing the bottom cover.
When disassembling the instrument, handle the PC board by the edges. Body performance. Keep the PC board clean and free of taminants.
1.
Place the unit face down on a bench or other similar surface and
remove the screws from the bottom cover.
2.
Separate the bottom cover from the rest of the instrument by
grasping the top of the case (just above the display) and carefully lifting it away from the display.
3. Remove the battery.
4.
Remove the standoff (ST-166-1) that secures the PC board to the
case.
The standoff is located in the center of the PC board.
5. Remove the switch cap.
6. Lift the PC board out of the top cover (front panel)
7. Remove the shield.
8. The LCD is held in place on the PC board by a shock resistant mounting and is assembled as shown in Figure 3.
9. To reassemble the unit, reverse the above procedure.
WARNING
NOTE
oil,
dirt, etc can degrade circuit
CAUTION
con-
When removing the not to spread the four retaining hooks
bezel out too far. The plastic bezel hooks may fracture.
LCD
from the PC board be careful
on
the clear plastic
WARNING When reassembling the instrument, be sure to reinstall the switch cover. Common mode voltage may be present on the switch creating a possible hazard if the cover Is not installed.
fUa K 7/V RLUSTtn
a HEQUIRED)
BOTTOM COVER
Figure 3. Model 873 Exploded View
BATTERY INSTALLATION/REPLACEMENT
To install or replace the battery:
1.
Remove the bottom cover of the instrument (refer to the
disassembly instructions).
WARNING Turn the instrument off and disconnect the input probe before removing the bottom cover. Reinstall the cover before resuming usa of the instrument.
2.
Remove the old battery.
3. Place the new battery in the battery compartment. Be sure to observe the proper polarity. Refer to Figure 4.
4.
Reinstall the bottom cover before resuming use of the instrument.
BArrenv
TERMINALS
Rgure 4. Battery Installation
CALIBRATION
Required Test Equipment
1.
DC voltage calibrator wrth
2.
100: 1 divider- 1.98k and 20n wirewound resistors, 0.02% ratio
±0.01%
of setting ±20/iV accuracy
accuracy or better.
3. OMEGA TRC III Ice Point Reference Chamber or distilled water ice bath.
4.
OMEGA type K TRP Reference Probe or make a thermocouple
Transition junction (see Calibration Set-Up).
Calibration Set-Up
1.
To make a thermocouple transition
of copper wire to each (type
K)
junction,
silver solder a piece
thermocouple wire and insulate the
junction with a waterproof jacket.
2.
Connect the thermocouple wires from the type K transition junc-
tion to an OMEGA Miniature Thermocouple Connector SMP-K-M.
3. Turn on the voltage calibrator.
4.
Plug in the miniature connector (see steps 1 and 2) into the 873
input.
5. Connect the copper wires to the 100:1 divider as shown in Figure
5. Connect the copper/chromel wire to the positive sida
6. Connect the 100:1 divider to the DC voltage calibrator as shown.
7. Use an OMEGA TRC III or prepare the distilled water ice bath as follows:
A. Drill a hole in the cap of a Dewar flask or Thermos™ to
accommodate the thermocouple,
B. Firmly pack the flask with pea-size ice cubes made from
distilled water and then fill the flask with distilled water.
10
C. Replace the melted ice with more ice while removing the excess
water.
D. Place the cap on the flask. Immerse the thermocouples into the
flask and allow 20 minutes for temperature stabilization.
DC CALIBRATOR
100:1 VOLTAGE DIVIDER
*The
ICE BATH
20(1
resistor must be at a uniform temperature during calibration.
873
Figure 5. Set-Up Procedure
Calibration Procedure
1.
Remove the bottom cover as described in the disassembly instruc-
tions.
WARNING To prevent a shock hazard, turn the instrument off and remove the Input probe from the instrument before removing the bottom cover.
2.
Turn on the Model 873 and perform the calibration adjustments
listed in Table 2 (873C) or Table 3 (873F). For access to calibra­tion adjustments refer to Figure 4.
11
Table 2. Modal 8730 Calibration Adjustments
Step
1 2 3 4
Adjustment
Zero
-i-Gain (xl) + Gain(x10)
-Gain
Range 200°C
1000°C
200°C
200°C
Calibrator
Setting
0.00000
+ 41.269mV
-H7.139mV
-1.527mV
Trimmer
Adjust
R112 R115 R104 R105
Desired
Reading
00.0°C 1000°C
175.0°C
-40.0°C
Table 3. Model 873F Calibration Adjustment
Step
1 2 3 4
Adjustment
Zero
-i-Gain(xl)
+ Gain(x10)
-Gain
Range
200°F
2000°F
200°F 200°F
Calibrator
Setting
-0.692mV
-i-44.645mV
3.589mV
-1.929mV
Trimmer
Adjust
R112 R115 R104 R105
Desired
Reading
00.0°F 1990°F
190.0°F
-60.0°F
PROBE MATCHING
To improve the accuracy of the Model 873 while using a particular proJTe, calibration can be adjusted so that probe errors in the region
of zero (0.0°C or 32°F) are compensated. Place the probe in an ice
bath and allow the reading to stabilize. Then reset the zero adjustment (R112) to a
0.0°C
or 32°F reading.
TROUBLESHOOTING
The following troubleshooting information is intended to be used by qualified electronic maintenance personnel who are familiar with the proper use of standard electronic test equipment.
To gain access to the PC board, refer to the disassembly instructions.
Use the parts list, schematic diagram and component layout to
iden-
tify parts and check point locations.
13
DC Voltage Checks
1.
Battery:
2.
-HV
VBAT>7.5V
to (Analog Ground) = -1-2.9 ±0.3V
3. -fV to (Digital Ground) = +5V ±1V
4.
Reference Diode
CR101 (Anode) to (Analog Ground) = -1.23V ±0.03V.
5. Negative reference divider (R114) referenced to analog ground. *
873C Pin 12 Pin 10 Pin 11 Pin 7 Pin 9 Pin 8 Pin 6 Pin 4 Pin 5 Pin 3 Pin 2
*The setting of Rl
= -1.23 V = -0.209V = -0.209V = -0.206V = -0.204V = -0.204V = -0.201V = -0.200V = -0.197V = -0.195V = -0.193V
15
and the tolerances of the resistors within the net-
Pin 12 Pin 11 Pin 10 Pin 9 Pin 8 Pin 7 Pin 6 Pin 5 Pin 4 Pin 3 Pin 2
work (R114) can affect these levels by ±5%.
6. Cold Junction Voltage (Ambient Temperature = 25°C ±3°C)
Across R102A approximately equal to ImV.
7. Waveform Checks (see Figure 6)
U104 pin 40 (OSC 1) U104 pin 39 (OSC 2) U104 pin 38 (OSC 3) U104 pin 21 (Backplane)
873F
= -1.23 V = -0.209V = -0.208V = -0.205V = -0.204V = -0.203V = -0.198V = -0.197V = -0.196V = -0.191V = -0.188V
13
U104 PIN 40 (OSC 1)
U104 PIN 39 (OSC 2)
H
25|isec
U104 PIN 38
K
= 25/(sec
-^'
K\/
5V
U104 PIN 21
M
= 20msec
Figure 6. Waveform Checks
14
BV
SPECIAL HANDLING OF STATIC SENSITIVE DEVICES
CMOS devices are designed to function at high impedance levels. Normal static charge can destroy these devices. Table 4 lists all the static sensitive devices for the Models 873C and 873F. Steps 1
through 7 provide instructions on how to avoid damaging these
devices.
Table 4. Static Sensitive Devices
Schematic
Designation
U104 U105
U107 U108
U109
1.
Devices should be handled and transported in protective
tainers, antistatic tubes or conductive foam.
2.
Use a properiy grounded work bench and a grounding wriststrap.
3. Handle devices by the body only.
4.
Printed circuit boards must be grounded to bench while inserting
devices.
5. Use antistatic solder removers.
6. Use grounded tip soldering irons.
7. After devices are soldered or inserted into sockets they are pro­tected and normal handling can resume.
con-
15
SPECIFICATIONS
MODEL 873F SPECIFICATIONS
TEMPERATURE SENSOR: Type K INICr-NiAl) Thermocouple,
RANGE SPAN RESOLUTION IBS to SyP; 2 years)
200°F -60.0° to 199.9° 0.1° ±(0,25% rdg -f-2.0°F)
2000°F -60° to 1999° 1^ ± (0.25% rdg -t- 2°F)
•Includes NBS confofmity, 82<'FI and
rors around 32°F may be compensated for by an intemal zero adjustment,
REPEATABILITY:
temperature.
TEMPERATURE COEFFICIENT: 65° to 82°F; included in accuracy
specification. From 14° to 65° and 82° to 122°F: less than ±(0,025% of rdg -(-0.2°F)/°F,
INPUT CURRENT: 25nA typical, 50nA maximum.
TEMPERATURE ACCURACY*
coW
repeatability
junction compensation, temperature coefficient
errors.
Excludes
therrtiocouple
0.3°F
typical for 1 week at constant ambient
errors;
however thermocouple
165°
to
er-
MODEL 8730 SPECIFICATIONS
TEMPERATURE SENSOR: Type K (Ni&NiAl) Thermocouple,
RANGE SPAN RESOLUTION (18 to 28°C: 2 yeara)
200°C -40.0° to 199.9° 0.1° ± (0.25% rdg -t-
1000°C -40° to 1000° 1° ±(0.25% rdg -I- 1°C)
"Includes NBS conformity, cold junction compensation, temperature coefficient
(18° to 28°C) and repeatability errors. Excludes thermocouple errors; however tfier­mocouple errors around 0°C may be compensated for by
REPEATABILrrV:
temperature.
TEMPERATURE COEFFICIENT: 18° to 28°C; included in accuracy
specification. From -10° to 18° and 28° to 50°C: less than ±(0.025% of rdg -(-0.1°C)/°C.
INPUT CURRENT: 25nA typical, 50nA maximum.
TEMPERATURE ACCURACY*
-55.0° to -40.0° 0.1° ±(0.25% rdg -t- 2.0°C)
-55° to -40° If ± (0.25% rdg + 2°C)
an
intemal zero adjustment,
0.2°C
typical for 1 week at constant ambient
1.0°C)
Specifications subject to change without notice.
16
MODEL 873F and 873C GENERAL SPECIFICATIONS (unless specified):
DISPLAY: 314 digit LCD, 13mnfi (0.5") height. Polarity and decimal point
indication. CONVERSION RATE: 2.5 readings per second. OVERRANGE AND OPEN SENSOR INDICATION: 3 least significant
digits blanked, MAXIMUM COMMON MODE VOLTAGE: 42V peak to earth. NORMAL MODE REJECTION RATIO: Greater than 40dB at 50 & 60Hz. COMMON MODE REJECTION RATIO: Greater than 120dB at DC, 50 &
60Hz, ENVIRONMENTAL LIMITS FOR OPERATING (Model 873F): 14° to
122°F,
less than 80% relative humidity up to 95°F; lineariy derate 1.5%
R.H./°F
ENVIRONMENTAL LIMITS FOR OPERATING (Model 873C): -10° to
ENVIRONMENTAL LIMITS FOR STORAGE (Model 873F): -30° to
ENVIRONMENTAL LIMITS FOR STORAGE (Model 873C): -35° to
THERMOCOUPLE LINEARIZATION: Multislope A/D with 11 piecewise THERMOCOUPLE INPUT: Miniature TC connector.
POWER: 9V alkaline or carbon-zinc (NEDA 1604) battery. BATTERY LIFE, CONTINUOUS: 350 hours typical with alkaline; 200
BATTERY INDICATOR: Display indicates "LO BAT" when less than 10% DIMENSIONS: 160mm long x 69mm vinde x 31mm thick (6,3" x CONSTRUCTION: Heavy duty ABS plastic housing.
ACCESSORIES SUPPLIED: Battery, Instruction Manual and Model
from 95° to 122°F.
50°C,
less than 80% relative humidity up to 35°C; lineariy derate 3%
R,H./°C
from 35° to 50°C.
140°F,
less than 90% relative humidity up to 95°F; linearly derate 1.5%
R,H,/°F
from 95° to 140°F,
60°C,
less than 90% relative humidity up to 35°C, linearly derate 3%
R.H./°C
from 35° to 60°C.
linear segments.
hours typical wrth carbon-zinc.
of life remains.
2.7" X 1.2").
TC-GG-K-24-36-SMP-f\/l Thermocouple Sensor
Net weight 210gm (7.5 oz.),
17
Model 8730 and 873F, Parts List
Sch Desig.
BT101
C101 C102 C103 0104
C105 C106
0107 0108 0109 0110
OR101
J1001 J1002
J1003 Q101
Q102 Q103
R101 R102* R102**
R103
R104* R104** R105 R106 R107 R108 R109 R110
Rill R112
R113
Description
9V Alkaline Battery, NEDA 1604
Capacitor, Capacitor, Capacitor, 33pF, 1000V, Ceramic Capacitor, .VF, 50V, Ceramic
Capacitor, .IjjF, 50V, Ceramic Capacitor, 47pF, 500V, Silver Mica or Ceramic Capacitor, .33f»F, 63V, Metalized
Polyester Capacitor, .047^F, 50V, Metalized Polypropylene Capacitor,
Electrolytic Capacitor, Polyester
Silicon Diode, 1N914 Miniature TC Connector, Female
Battery Clip Battery Clip Transistor, NPN, 2N3904
Transistor, NPN, 2N3904
Transistor, PNP, 2N3906
Resistor, 10k, 5%, 1/4W, Composition Thick Film Resistor Networic Thick Rim Resistor Network
Resistor, 10M, 5%, 1/4W, Composition
Potentiometer, Ik Potentiometer, 50012 Potentiometer, 2k Thick Film Resistor Network
Resistor, 191k, 1%, 1/8W, Metal Film Resistor, 390k, 5%, 1/4W, Composition Thick Film Resistor Network Factory Selected Resistor (Part of A31419) Factory Selected Resistor (Part of A31410) Potentiometer, 2k Factory Selected Resistor (part of
A31419)
.^^lf,
50V, Ceramic
.l/iF,
50V, Ceramic
4.7/JF,
25V, Aluminum
.33MF,
63V, Metalized
Sch
Location
Fl
Bl C2 82 G1 G1
E2
F2
E2 G5 Dl
E3
A2
Fl Fl
B2 82 E3
A2
Sev Sev
Dl Dl Dl D2
Sev
F2
F2
Sev
83 83 83
C3
18
Modei 873C and 873F, Parts Ust (Cont.)
Sch
Desig. R114*
RIM"" R115 R116 R117 R118
S101 U101
U102 U103
U104 U105 U106 U107 U108 U109
VR101 W101
•Model 873F
"Model 8730
NOTE:
Description
Thick Film Resistor Network Thick Film Resistor Networi< Potentiometer, 2k Resistor, 100k, 5%, 1/4W, Composition Resistor, 100k, 5%, 1/4W, Composition Resistor, 121k, 1%, 1/8W, Metal Film
Switch,
4P3T, On/Off Range Switch
Op Amp, LM308 (Factory selected; part of A31419) Current Source, LM334 (Factory selected; part of A31410)
Low Power JFET Op Amp, TL062Cp 3-1/2 Digit A/D Converter, ICL7136 Quad 2 Input NOR Gate, 4001
Dual Synchronous Up Counter, 4518
12 Stage Binary Counter, 4020 Analog Multiplexer, 4051 Analog Multiplexer, 4053
Reference Diode, 1.23V Jumper Wire
Mechanical Parts can be found in the expk>ded view (Figure 3).
Location
D2/G5
Sch
Sev Sev
F4 G4 86 Dl
Sev
C2 03
F2
Sev
05 05 D5
G5 85
19
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FAX: (203)359-7700
CT 06907-0047
HMDilOOKAiio
BIEYiaOFEIllA
Phone: (203)359-1660
/^OMEGA
lA^
.AH
An OIWEGA Group Company
ENGiiUEERiNG.
IIMC.
"The WORLD'S Leader in the Field of
Sensing and Control"
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designated AR number should then be marked on the outside of the
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2.
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.AH
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