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®

51, 52, 53, 54 Series II

Thermometer

Service Manual

PN 1276123 October 1999
© 1999 Fluke Corporation. All rights reserved. Printed in USA All product names are trademarks of their respective companies.

LIMITED WARRANTY & LIMITATION OF LIABILITY
Each Fluke product is warranted to be free from defects in material and workmanship under normal use and service. The warranty period is three years and begins on the date of shipment. Parts, product repairs and services are warranted for 90 days. This warranty extends only to the original buyer or end-user customer of a Fluke authorized reseller, and does not apply to fuses, disposable batteries or to any product which, in Fluke's opinion, has been misused, altered, neglected or damaged by accident or abnormal conditions of operation or handling. Fluke warrants that software will operate substantially in accordance with its functional specifications for 90 days and that it has been properly recorded on non-defective media. Fluke does not warrant that software will be error free or operate without interruption. Fluke authorized resellers shall extend this warranty on new and unused products to end-user customers only but have no authority to extend a greater or different warranty on behalf of Fluke. Warranty support is available if product is purchased through a Fluke authorized sales outlet or Buyer has paid the applicable international price. Fluke reserves the right to invoice Buyer for importation costs of repair/replacement parts when product purchased in one country is submitted for repair in another country. Fluke's warranty obligation is limited, at Fluke's option, to refund of the purchase price, free of charge repair, or replacement of a defective product which is returned to a Fluke authorized service center within the warranty period. To obtain warranty service, contact your nearest Fluke authorized service center or send the product, with a description of the difficulty, postage and insurance prepaid (FOB Destination), to the nearest Fluke authorized service center. Fluke assumes no risk for damage in transit. Following warranty repair, the product will be returned to Buyer, transportation prepaid (FOB Destination). If Fluke determines that the failure was caused by misuse, alteration, accident or abnormal condition of operation or handling, Fluke will provide an estimate of repair costs and obtain authorization before commencing the work. Following repair, the product will be returned to the Buyer transportation prepaid and the Buyer will be billed for the repair and return transportation charges (FOB Shipping Point). THIS WARRANTY IS BUYER'S SOLE AND EXCLUSIVE REMEDY AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. FLUKE SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL OR CONSEQUENTIAL DAMAGES OR LOSSES, INCLUDING LOSS OF DATA, WHETHER ARISING FROM BREACH OF WARRANTY OR BASED ON CONTRACT, TORT, RELIANCE OR ANY OTHER THEORY. Since some countries or states do not allow limitation of the term of an implied warranty, or exclusion or limitation of incidental or consequential damages, the limitations and exclusions of this warranty may not apply to every buyer. If any provision of this Warranty is held invalid or unenforceable by a court of competent jurisdiction, such holding will not affect the validity or enforceability of any other provision. Fluke Corporation P.O. Box 9090 Everett WA 98206-9090 U.S.A Fluke Europe B.V. P.O. Box 1186 5602 B.D. Eindhoven, The Netherlands

Table of Contents

Title Introduction ....................................................................................................... Service Centers.................................................................................................. International Symbols........................................................................................ Precautions and Safety Information .................................................................. General Specifications .................................................................................. Environmental ............................................................................................... Electrical ....................................................................................................... Performance Test and Calibration Required Test Equipment ........................... Performance Tests ............................................................................................. Display Test .................................................................................................. Keypad Test .................................................................................................. Wide Range Performance Test Procedure .................................................... Ice Bath Construction ............................................................................... Ice Bath Test ............................................................................................. Verification of IR Communications Port (Fluke 53 and 54)......................... Calibration and Offset Adjustment.................................................................... A/D Calibration............................................................................................. Reference Junction Calibration ..................................................................... Using the Offset to Adjust for Variation Between Thermocouples .............. Basic Maintenance............................................................................................. Cleaning the Thermometer............................................................................ Changing the Batteries .................................................................................. Disassembly and Reassembly............................................................................ Disassembly .................................................................................................. Reassembly ................................................................................................... Reinstalling the LCD Assembly ............................................................... Rebuilding the Main PCA......................................................................... Reinstalling the Main PCA ....................................................................... Replaceable Parts............................................................................................... Index

Page 1 2 2 2 4 4 4 5 5 5 6 6 6 7 8 9 9 11 11 12 12 12 13 13 14 14 14 15 15

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51, 52, 53, 54 Series II
Service Manual

ii

List of Tables

Table 1. 2. 3. 4.

Title International Electrical Symbols Used in this Manual........................................... Recommended Test Equipment ............................................................................. Performance Test Values (K-Type Thermocouple)............................................... Replaceable Parts ...................................................................................................

Page 2 5 8 15

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iv

List of Figures

Figure 1. 2. 3. 4. 5. 6.

Title Display Segments .................................................................................................. Ice Bath Test Equipment Connections................................................................... Calibration Connections ........................................................................................ Calibration Button Access ..................................................................................... Battery Access ....................................................................................................... Exploded View (Model 54 is Shown)....................................................................

Page 6 7 9 10 13 17

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51, 52, 53, 54 Series II Service Manual

WWarning
To avoid shock or injury, do not perform the performance tests or calibration procedures described in this manual unless you are qualified to do so. Refer to the Safety Information section of this manual before using the Fluke 51, 52, 53, 54 Series II Thermometers. Caution The Fluke 51, 52, 53, 54 Series II Thermometers contain parts that can be damaged by static discharge. Follow the standard practices for handling static sensitive devices.

Introduction
This manual provides the following service information for the 51, 52, 53, and 54 Series II Thermometers, hereafter referred to as "the thermometer". · · · · · · Precautions and safety information Specifications Performance tests Calibration and adjustment Basic maintenance Replaceable parts

For complete operating instructions, refer to the 51/52 Series II Users Manual or the 53, 54 Series II Users Manual, located on the 51/54 Series II CD ROM, part number 1276106.

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51, 52, 53, 54 Series II
Service Manual

Service Centers
To contact Fluke, order parts, or locate a Fluke service center, call one of the following telephone numbers: USA: 1-888-99-FLUKE (1-888-993-5853) Canada: 1-800-36-FLUKE (1-800-363-5853) Europe: +31 402-678-200 Japan: +81-3-3434-0181 Singapore: +65-738-5655 Anywhere in the world: +1-425-446-5500 Or, visit Fluke's Web site at www.fluke.com.

International Symbols
Table 1 identifies the international electrical symbols used in this manual.
Table 1. International Electrical Symbols Used in this Manual

B

Low Battery Complies with relevant Canadian Standards Association directives

Important information Complies with European Union directives

Precautions and Safety Information
Use the thermometer only in the ways specified in the 51/52 Series II Users Manual and the 53/54 Series II Users Manual. If the thermometer is used in ways not specified, the thermometer may be damaged. In this manual, a Warning statement identifies conditions and actions that pose a hazard to the user; a Caution statement identifies conditions and actions that may damage the thermometer or the test instruments.

2

Thermometer
Precautions and Safety Information

Safety Information WWarning
To avoid electrical shock or personal injury, follow these guidelines: · Before using the thermometer, inspect the case. Do not use the thermometer if it appears damaged. Look for cracks or missing plastic. Pay particular attention to the insulation around the connectors. Disconnect the thermocouple(s) from the thermometer before opening the case. Replace the batteries as soon as the low battery indicator (B) appears. The possibility of false readings can lead to personal injury. Do not use the thermometer if it operates abnormally. Protection may be impaired. When in doubt, have the thermometer serviced. Do not operate the thermometer around explosive gas, vapor, or dust. Do not apply more than the rated voltage, as marked on the thermometer, between the thermocouple(s), or between any thermocouple and earth ground. Models 52 and 54: Measurement errors may occur if voltages on the measurement surfaces result in potentials greater than 1 V between the two thermocouples. When potential differences are anticipated between the thermocouples, use electrically insulated thermocouples. When servicing the thermometer, use only specified replacement parts. Do not use the thermometer with any part of the case or cover removed.

· · · · ·

·

· ·

Caution
To avoid damaging the thermometer or the equipment under test: · · · · · Use the proper thermocouples, function, and range for your thermometer. Do not attempt to recharge the batteries. To prevent explosion, do not dispose of batteries in fire. Follow local laws or regulations when disposing of batteries. Match the + and - polarities of the batteries with the battery case markings.

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51, 52, 53, 54 Series II
Service Manual

Specifications
General Specifications
Weight Dimensions (without holster) Battery Certification Safety 280 g (10 oz) 2.8 cm × 7.8 cm × 16.2 cm (1.1 in × 3 in × 6.4 in) 3 AA batteries P, ) (TÜV pending)

CSA C22.2 No. 1010.1 1992 EN 61010 Amendments 1, 2 CAT I OVERVOLTAGE (Installation) CATEGORY I, Pollution Degree 2 per IEC1010-1* * Refers to the level of Impulse Withstand Voltage protection provided. Equipment of OVERVOLTAGE CATEGORY I is equipment for connection to circuits in which measures are taken to limit the transient over voltages to an appropriate low level.

Environmental
Operating Temperature Storage Temperature -10 C to +50 C (+14 F to +122 F)
o o o o o

-40 C to +60 C (-40 F to +140 F)
o o o

Humidity

Non Condensing (< +10 C) (< +50 F) o o o o 95% RH (+10 C to +30 C) (+50 F to +86 F) o o o o 75% RH (+30 C to +40 C) (+86 F to +104 F) o o o o 45% RH (+40 C to +50 C) (+104 F to +122 F) (Without Condensation)

o

o

Electrical
Measurement Range J-type: -210 C to +1200 C (-346 F to +2192 F) o o o o K-type: -200 C to +1372 C (-328 F to +2501 F) o o o o T-type: -250 C to +400 C (-418 F to +752 F) o o o o E-type: -150 C to +1000 C (-238 F to +1832 F) o o o o N-type: -200 C to +1300 C (-328 F to +2372 F) o o o o R- and S-type: 0 C to +1767 C (+32 F to +3212 F) o o o 0.1 C / F / K < 1000 o o o 1.0 C / F / K 1000 o o J-, K-, T-, E-, and N-type: ±[0.05 % of reading + 0.3 C (0.5 F)] o o [below -100 C (-148 F): add 0.15 % of reading for J, K, E, and N; and 0.45 % of reading for T] o o R- and S-type: ±[0.05 % of reading + 0.4 C (+0.7 F)] o o 0.01 % of reading + 0.03 C per C o o o o o o (0.05 F per F) outside the specified +18 C to +28 C (+64 F to +82 F) range o o [below -100 C (-148 F): add 0.04 % of reading for J-, K-, E-, and N-type; and 0.08 % of reading for T-type] o o Susceptibility: ± 2 C (± 3.6 F) for 80 MHz to 200 MHz in 1.5 v/m field, for 200 MHz to 1000 MHz in 3 V/m field. Emissions: Commercial limits per EN50081-1
o o o o

Display Resolution Measurement Accuracy

Temperature Coefficient Electromagnetic Compatibility

Maximum Differential Common Mode Voltage 1 V (Maximum voltage difference between T1 and T2) Temperature Scale ITS-90 Applicable Standards NIST-175 o o o o Accuracy is specified for ambient temperatures between +18 C (+64 F) and +28 C (+82 F) for a period of 1 year. The above specifications do not include thermocouple error.

4

Thermometer
Performance Test and Calibration Required Test Equipment

Performance Test and Calibration Required Test Equipment
Refer to Table 2 for a list of test equipment used in the performance test and calibration procedures.
Table 2. Recommended Test Equipment Equipment DC Voltage Calibrator Thermocouple connector Thermocouple connector K-type Thermocouple wire Dewar Flask/Cap Mercury Thermometer (either °C or °F) DB9 Adapter Connector IR Adapter PC with Microsoft Windows installed
®

Required Characteristics Output Voltage: 0-1V Accuracy: 0.0125 % Resolution: 0.1 µV For K-type thermocouple Copper Standard 1- pint, or larger capacity 0.02 °C Resolution 0.05 °F Resolution

Recommended Model

Fluke 5700A or equivalent Fluke 80CK-M Fluke P/N 779942 Fluke P/N 601747 Omega Thermos Princo Model ASTM56C Princo Model ASTM56F Fluke P/N 804549 Fluke P/N 690518

Performance Tests
Performance tests are recommended for incoming inspection, periodic maintenance, and for checking the thermometer's specifications. If the thermometer fails any part of the performance tests, calibration and/or repair is indicated. Before performing these tests:
o o o o 1. Allow the thermometer to stabilize to room temperature, +23 C ± 5 C (+73 F ± 9 F).

2. Check the batteries and replace them if necessary.

Display Test Turn the thermometer on while pressing the h button. All display segments are displayed until the h button is released. Confirm that all the display segments are showing as in Figure 1.

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Service Manual

51

53

52

54

zb03f.eps

Figure 1. Display Segments

Keypad Test Check that all keypad switches are functional by pressing each key and confirming the proper response on the display. Wide Range Performance Test Procedure This test verifies the instrument specifications. If the instrument fails this test, perform the calibration procedure. If the unit continues to fail, it should be taken to a Fluke service center. Ice Bath Construction To begin the performance test, first construct an ice bath as follows:
1. Prepare a Dewar Flask by drilling two holes in its cap to accept the Mercury thermometer and thermocouple wires, or use a standard laboratory cork. 2. Fill the Dewar Flask with shaved or crushed ice made from distilled water. 3. Fill the Dewar Flask with enough distilled water so that the ice turns to slush, but do not add enough water to float the ice. Note As the ice melts, siphon off the excess water and add more ice. Allow approximately 5 to 10 minutes for the water to drop back to the freezing point.

6

Thermometer
Performance Tests

4. Replace the Dewar Flask cap or cork, and insert the thermocouple wires and Mercury thermometer as shown in Figure 2. Insert the Mercury thermometer to the same depth as the thermocouple wire.
K-Type Thermocouple wire

_

Mercury Thermometer + +

51, 52, 53, or 54 Series II Thermometer + 5700A Calibrator Ice bath

_

Copper wire

K-Type Thermocouple connector

zb04f.eps

Figure 2. Ice Bath Test Equipment Connections

Ice Bath Test Use the following procedure to test the thermometer. If the thermometer has two inputs, this test should be conducted on both thermocouple inputs.
1. If not already selected, select K-type thermocouple on the thermometer using the D, K, N, and E buttons. 2. Connect the equipment as shown in Figure 2. Allow the setup to thermally stabilize at least 5 minutes after inserting the thermocouple into the thermometer. 3. Verify that the ice bath temperature reads 0.0 C ± 0.06 C on the Mercury thermometer.
o o

4. Short (or apply 0 mV) to the copper wires at the Calibrator. 5. Verify the thermometer reads 0.0 oC ± 0.3 oC. 6. If this test fails, reposition the thermocouple wires and Mercury thermometer to the same depth in the ice bath, and repeat steps 3-5. If the test continues to fail, perform the calibration procedure, located after this procedure. 7. Remove the short applied in step 4. 8. Using Table 3, steps 2-5, obtain an output from the Calibrator equal to the values in the "Input Voltage (mV DC)" column, and verify the thermometer reads within the limits specified. If any step fails, perform the calibration procedure located later in this section. 9. Disconnect the thermocouple from the input terminals. This completes the ice bath test.
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51, 52, 53, 54 Series II
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Table 3. Performance Test Values (K-Type Thermocouple) Input Voltage Step 1 2 3 4 5 (mV DC) 0.0000 0.9193 -5.7297 40.8853 48.8382 0.0 °C 23.0 °C -190.0 °C 990.0 °C 1200 °C

Equivalent Temperature 32.0 °F 73.4 °F -310.0 °F 1814 °F 2192 °F

Display Reading limits °C -0.3 to 0.3 22.7 to 23.3 -189.3 to -190.7 989.2 to 990.8 1199 to 1201 °F 31.5 to 32.5 72.9 to 73.9 -308.9 to -311.1 1813 to 1815 2190 to 2194

Verification of IR Communications Port (Fluke 53 and 54) This section explains how to verify the operation of the IR Communications Port (IR port). Perform the following procedure using a PC and HyperTerminal. The IR port can also be verified using FlukeviewTM software.
To set up a HyperTerminal file, follow these steps: 1. Connect the IR adapter cable to the DB9 Adapter connector. Connect the other end of the DB9 Adapter to a COM port of the PC. 2. Place the Fluke 53 or 54 in front of the IR adapter. 3. Open up a HyperTerminal session. Select Start button, Programs, Accessories, HyperTerminal. 4. Open up a New Connection with a name like "Fluke 54 IR Test". 5. When the Connect To box appears, select the COM1 or COM2 (the port that the IR adapter cable is plugged into). 6. Select Port Settings: 9600 baud rate, 8 data bits, no parity, 1 stop bit, and no flow control. 7. Under File, select properties. Verify that the correct port is selected. Click on Configure. Verify that port settings are correct (the baud rate may need to be changed to 9600). 8. Select the Settings tab then click on ASCII Setup. Check the following boxes: · · · Echo typed characters locally Append line feeds to incoming line ends Wrap lines that exceed terminal width

To open a HyperTerminal file to test the IR port, use the following procedure: 1. Under File, select Save As. Use a file name such as "Fluke 54 IR Test" and then click on save. 2. Click on the phone disconnect icon. 3. Click on open folder or under File select Open. Double click on Fluke 54 IR Test. 4. Type in "ID" followed by the Enter key (notice the "ID" is capitalized). 5. The display of the thermometer now shows the thermometer name (Fluke 53-II or Fluke 54-II), and the units operating software version (e.g. Fluke 54-II, V1.01).
8

Thermometer
Calibration and Offset Adjustment

Calibration and Offset Adjustment
Calibration consists of two parts: 1. Calibration of the A/D converter, using the set up shown in Figure 3. 2. Reference junction calibration, using the ice bath test set up shown in Figure 2.

A/D Calibration To calibrate the A/D portion of the thermometer, follow these steps:
1. Connect the calibrator to the T1 input of the thermometer using copper (nonthermocouple) wire and a copper thermocouple connector. Refer to Figure 3 for proper equipment connections. 2. Turn the thermometer on, with a small, blunt probe, press the calibration button located on the back and in the center of the thermometer. Refer to Figure 4.

Copper Thermocouple connector

-

Copper wire 5700A Calibrator

51, 52, 53, or 54 Series II Thermometer

+ -

_
+

zb06f.eps

Figure 3. Calibration Connections

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51, 52, 53, 54 Series II
Service Manual

Calibration button access

zb02f.eps

Figure 4. Calibration Button Access

3. The menu on the display changes to "CAL A-d". Note Within CAL are four menu options that may be accessed by pressing E: · · · ·
CAL A-d prompts the operator for the A/D calibration inputs in mV dc. CAL rEF allows the operator to calibrate the reference junction at a known temperature. CAL donE saves the new calibration constants in memory. CAL Abrt ignores calibration changes (turning the thermometer off while in CAL will also ignore calibration changes).

4. Press K or N to select different menu options. 5. With CAL A-d selected, press E. The thermometer prompts "80". Set the calibrator to +80.000 mV and allow the output to stabilize. Note For steps 6 and 8, keep hand and body motion to a minimum while the thermometer takes A/D readings. 6. Press E. Wait while it takes A/D readings. 7. When the thermometer prompts for "-8", set the Calibrator to -8.0000 mV. Allow the output to stabilize. 8. Press E on the thermometer and wait while it takes A/D readings. The thermometer now shows the measured value in the bottom portion of the display. Millivolts appears on the left side and microvolts appears on the right side. 9. If the measurement is from ­7 995.0 to ­8 005.0, press E and the meter will return to the calibration menu and display CAL rEF. If the measurement is outside ­ 7995.0 to ­8005.0, press E once to return to the calibration menu. Using K or N, select CAL A-d and try the A/D calibration procedure a second time starting at step 5. 10. Using K or N, select "CAL donE", then press E to store the calibration in memory.

10

Thermometer
Calibration and Offset Adjustment

11. To ignore the calibration changes, use K or N, and select "CAL Abrt" and press E. 12. Proceed to Reference Junction Calibration.

Reference Junction Calibration
Note This procedure is described using an ice bath and a K-type thermocouple. It can be performed in °C, °F, or K with any thermocouple and a known, accurate temperature between 0 °C (+32 °F) and +50 °C (+122 °F). Note It is important that the temperature of the thermocouple and the internal temperature of the thermometer (the reference junction) have stabilized. To calibrate the reference junction, follow these steps: 1. Prepare an ice bath (described earlier in this section). 2. Referring to Figure 2, connect the equipment to T1 using K-type thermocouple wire and a K-type thermocouple connector. Allow the setup to thermally stabilize at least 5 minutes after inserting the thermocouple connector into the thermometer. 3. Turn the thermometer on and select the thermocouple type using the D, K, N, and Ebuttons. 4. Enter calibration mode (refer to the "A/D Calibration" section, step 2). 5. Using K or N, select CAL rEF and press E. 6. Press K or N until the upper display matches the known temperature. Note Once adjusted, do not change units (°C, °F, or K) until the thermometer is in measurement mode. 7. Press the E button. 8. "CAL donE"appears then press E to store the calibration in memory. 9. To ignore the calibration changes, use the K or N, and select "CAL Abrt" and press E.

Using the Offset to Adjust for Variation Between Thermocouples Use the offset option in the thermometer SETUP mode to adjust the thermometer's readings for errors of a specific thermocouple. Use the following procedure:
1. Plug the thermocouple into the thermometer input then allow the setup to thermally stabilize at least 5 minutes. 2. Place the thermocouple in a known, stable temperature environment (such as an ice bath, lag bath, or a dry well calibrator). 3. Allow the readings to stabilize. 4. In SETUP, change the offset until the primary display reading matches the bath temperature. (See "Changing Setup Options" in the 51/52 Series II Users Manual, and the 53/54 Series II Users Manual.)

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51, 52, 53, 54 Series II
Service Manual

Basic Maintenance
Basic maintenance required by the thermometer is discussed in this section.

Cleaning the Thermometer
· Caution To avoid damaging the thermometer, do not use aromatic hydrocarbons or chlorinated solvents for cleaning. These solutions react with the plastics used in the thermometer. Do not allow the LCD to get wet. Do not remove any of the lubricant from the battery/pca connection.

· ·

Clean the thermometer case with a mild detergent and water. The pca may be washed with isopropyl alcohol or deionized water and a soft brush. Dry o o the pca with clean dry air at low pressure, then bake it at +50 C (+122 F) for 24 hours.

Changing the Batteries
·

WWarning
Replace the batteries as soon as the low battery indicator (B) appears. The possibility of false readings increases when the batteries are low. False readings can lead to personal injury. To avoid electrical shock, disconnect the thermocouple(s) before opening the battery door. Caution Do not attempt to recharge the batteries. Do not dispose of the batteries by placing them in fire. Follow local laws or regulations when disposing of batteries. Match the positive (+) and negative (-) polarities of the batteries with the markings located on the case.

·

· · · ·

To replace the batteries, refer to Figure 5 and use the following procedure: 1. Turn the thermometer off. 2. Loosen the battery compartment door screw and remove the battery door. 3. Replace the three AA batteries. To simplify battery installation, put the new batteries into the unit positive end first. 4. Replace the battery compartment door and tighten the screw.

12

Thermometer
Disassembly and Reassembly

zb01f.eps

Figure 5. Battery Access

Disassembly and Reassembly
Disassembly and reassembly of the thermometer may be necessary to replace interior parts. Refer to Figure 6 when disassembling and reassembling the thermometer.

Disassembly To disassemble the thermometer, follow these steps:
1. Remove the batteries (see "Changing the Batteries" section). 2. Remove the two screws located inside the battery compartment. · Caution Before proceeding, make sure that you are grounded to prevent static discharge, which could damage the thermometer. Inside the unit there are parts that can become contaminated by oils from the skin. These parts should not be directly handled. When lifting out the elastomeric connectors and the main switch pad, it is recommended that tweezers or sterile gloves be used.

·

3. Remove the two case bottom screws, located at the LCD-end of the unit and separate the bottom case from the top case. 4. Removing any of the interior components of the unit requires removing the Main PCA. To remove the Main PCA, place the top case face down and remove the two screws that attach the Main PCA to the top case. Gently lift the Main PCA out of the top case. The IR Lens, small Isothermal PCA, backlight, elastomeric connectors, and the LCD may all lift out attached to the Main PCA. 5. If the Isothermal PCA separates from the Main PCA, the Isothermal PCA, IR Lens, backlight, elastomeric connectors, and the LCD will still be in the top case. Lift them out of the top case after the Main PCA is removed.
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51, 52, 53, 54 Series II
Service Manual

6. The LCD decal is now exposed and may be removed. 7. To remove the main switch pad, first remove the small elastomeric connector at the top of the switch pad, and then lift out the entire switch pad.

Reassembly The reassembly procedure is basically the reverse of the disassembly procedure. However, there are several points in this process that should be explained further.
Note For reassembly, the thermometer top case should be face down, with the keypad end of the top case facing the user.

Reinstalling the LCD Assembly Follow these steps to reinstall the LCD assembly:
1. Install the LCD decal. 2. When putting the LCD back into the top case, make sure the LCD is correctly aligned. The edge of the LCD with the bubble in it should be facing the left side of the open, face down top case, and the LCD should be placed into the top case face down. 3. When reinstalling the backlight, the backlight pins should be on the left side of the open top case and they should be facing up. Check that the pins are straight. To make sure that the backlight is centered, line up the bottom left corner of the backlight with the guide that is molded into the top case. The left corner of the backlight should fit directly over this guide and the bottom right side of the backlight should also be lined up with (but not over) a similar guide on the right side of the open top case. 4. Install the two LCD elastomeric connectors.

Rebuilding the Main PCA When reinstalling the Main PCA, make sure that the Isothermal PCA and the IR Lens are attached to each other first. To do this, follow these directions:
1. Turn the Main PCA over so that the components are face down. 2. Attach the Isothermal PCA to the Main PCA by inserting the pins into the matching holes on the Main PCA. Note When putting the Isothermal PCA back onto the Main PCA, do not push the Isothermal PCA all the way down into the contact holes of the Main PCA. If the Isothermal PCA is kept slightly loose, it makes installation of the IR Lens easier. 3. Reinstall the IR Lens by taking the Main PCA (with the Isothermal PCA loosely attached), and with the component side facing down; slide the IR Lens in between the main board and the Isothermal PCA. 4. Line up the tab on the Isothermal PCA and the notch in the IR Lens and push the two together. The contacts of the IR Lens should slide under the Isothermal PCA and they should be making contact with pads on the underside of the Isothermal PCA.

14

Thermometer
Replaceable Parts

5. Push the Isothermal PCA and the Main PCA together so that the Isothermal PCA pins go deeper into the Main PCA sockets. This holds the IR Lens in place and allows the Main PCA to be reinstalled into the top case.

Reinstalling the Main PCA 1. While holding the IR Lens to the Main PCA, turn the Main PCA over so that the components are facing up.
2. Align the screw holes in the Main PCA with those in the top case. 3. Align the backlight pins with the Main PCA sockets. 4. Align the Main PCA holes with the backlight posts. 5. Gently push the Main PCA down into the top case, making sure that the IR Lens goes into the groove on the LCD-end of the top case. If it does not fit together easily, check to make sure that everything is properly lined up and try again. 6. Reinsert and tighten the two pca screws. To complete the thermometer reassembly, screw the bottom case to the top case, reinstall the batteries and screw the battery compartment shut.

Replaceable Parts
Refer to Table 4 for all replacement part numbers and Figure 6 for part locations. Unless specified in the "Model Number" column, all parts are for all units. To order replaceable parts, see the "Service Centers" section of this manual.
Table 4. Replaceable Parts Item Number
1 2

Qty.
3 4

Fluke Part Number
376756 803582

Description
BATTERY, PRIMARY, 1.5V, 0-150MA, AA ALKALINE SCREW , PH, P, CAPT, STL, 4-40, .25 BATTERY DOOR:

Model Number
All All

3 4 5

1 1 1

642931 669838 669812 669804 669801 669796 1541901 804713 1541895

· SCREW, PH, P, AM THD FORM, STL, 4-14, .312 · DOOR, BATTERY CASE, TOP CASE, TOP CASE, TOP CASE, TOP ISOTHERMAL PCA (TESTED) CONNECTOR, ELASTOMERIC, LCD TO PWB, 2.210 L BOTTOM CASE ASSEMBLY

All All 51 52 53 54 All All All

6 7 8A-F

1 2 1

Bottom Case Assembly contains:
8A 8B 8C 8D 8E 8F 2 1 1 1 1 1 666435 674744 674770 669819 658689 675009 · · · · · · BATTERY CONTACT, DUAL BATTERY CONTACT (POS) BATTERY CONTACT (NEG) CASE, BOTTOM KEYPAD, CALIBRATION SHIELD All All All All All All

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51, 52, 53, 54 Series II
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Table 4. Replaceable Parts (cont.) Item Number
9A-B

Qty.
1 1

Fluke Part Number
1541912 1543462

Description
51/53 SERIES II IR LENS KIT 52/54 SERIES II IR LENS KIT

Model Number
51, 53 52, 54

IR Lens Kit contains:
9A 2 4 1 1 10 11 1 1 675017 675030 675025 675022 675014 674747 1272438 643830 669793 669788 669785 669777 804705 800836 1276106 __ · · · SPRING, ISOTHERMAL 51, 53 52, 54 51, 53 52, 54 All 51 52 53 54 All All All 51 52 53 54 All All All

9B

__

IR LENS IR LENS

WINDOW, PROTECTOR LCD DECAL LCD DECAL LCD DECAL LCD DECAL BACKLIGHT HOLSTER & FLEX STAND ASSEMBLY SCREW, PH, P, METRIC PT, STL, K35, 14MM KEYPAD KEYPAD KEYPAD KEYPAD CONNECTOR, ELASTOMERIC, SWITCH TO PWB, 1.200 L LCD, MULTIPLEXED CD ROM, CD ROM FLUKE 50 SERIES II CD ROM contains: · · 51/52 Series II Users Manual (16 Languages) 53/54 Series II Users Manual (16 Languages)

12 13 14 15

1 1 2 1

16 17 Not shown

1 1 1

Not shown Not shown

1 1 2

1276114 773135

FLUKE 51-54 SERIES II PRODUCT OVERVIEW THERMOCOUPLE ASSY, T/C ASSY, K-TYPE, BEADED, MOLDEDPLUG

All 51, 53 52, 54

16

Thermometer
Replaceable Parts

10

5

11

17

9B 9A 15 6

8B 7 16 8C

12

8E

8F

8D

8A 2 1

14

13 3

4

zb07f.eps

Figure 6. Exploded View (Model 54 is Shown)

17

51, 52, 53, 54 Series II
Service Manual

18

Index

--A--
assembly, 13

--I--
ice bath construction, 6 equipment connections, 7 test, 7

--B--
batteries access to, 13 changing, 12

--L--
LCD reinstalling, 14

--C--
calibration, 9 A/D, 9 A/D connections, 9 button access, 10 CAL Abrt, 10 CAL A-d, 10 CAL donE, 10 CAL rEF, 10 offset, 9 reference junction, 11 variations between thermocouples, 11 caution, 12, 13 CD ROM, 1

--M--
Main PCA rebuilding, 14 reinstalling, 15 maintenance basic, 12 batteries, changing, 12 cleaning, 12

--P--
parts diagram, 17 list of replaceable, 15 performance tests, 5 display test, 5 IR communications port verification, 8 keypad test, 6 test values, k-type thermocouple, 8 wide range, 6 precautions, 2

--D--
disassembly, 13 display segments, 6

--E--
electrical symbols, 2

--H--
HyperTerminal, 8

--R--
reassembly, 14

1

51, 52, 53, 54 Series II
Service Manual

--S--
safety, 2 cautions and warnings, 3 service centers phone numbers, world wide web address, 2 specifications electrical, 4 environmental, 4 general, 4

performance testing and calibration, 5

--U--
Users Manual 51, 52 Series II, 1 53, 54 Series II, 1

--W--
warnings, 1, 12

--T--
test equipment

2