Fluke 525A Service Manual

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Page 1

525A

Temperature/Pressure Calibrator

Service Manual

PN 1644492 March 2002

Page 2

LIMITED WARRANTY AND 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 one year 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, contaminated, 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 only 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 to obtain return authorization information, then send the product to that service center, with a description of the difficulty, postage and insurance prepaid (FOB Destination). 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 failure was caused by neglect, misuse, contamination, alteration, accident, or abnormal condition of operation or handling, including overvoltage failures

caused by use outside the product’s specified rating, or normal wear and tear of mechanical components, 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, ARISING FROM ANY CAUSE OR 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 or other decision-maker 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.

11/99

Fluke Europe B.V. P.O. Box 1186 5602 BD Eindhoven The Netherlands

To register your product online, visit register.fluke.com

Page 3

Title Page

Introduction....................................................................................................... 1

Contacting Fluke ............................................................................................... 1

Safety Information............................................................................................. 1

Calibrator Specifications ................................................................................... 3

General Specifications .................................................................................. 3

DC Voltage Specifications, Output............................................................... 4

DC Current Specifications, Output............................................................... 4

Resistance Specifications, Output................................................................. 5

Resistance Specifications, Input.................................................................... 5

Thermocouple Specification, Output and Input............................................ 6

TC mV Specifications, Input and Output...................................................... 7

RTD and Thermistor Specification, Output.................................................. 8

RTD and Thermistor Specification, Input..................................................... 9

Pressure Measurement .................................................................................. 11

Theory of Operation.......................................................................................... 11

Micro-Controller Section.............................................................................. 11

Analog Section.............................................................................................. 12

Basic Maintenance............................................................................................. 12

Cleaning the Calibrator................................................................................. 12

Replacing a Line Fuse................................................................................... 12

To Check or Replace a Fuse.......................................................................... 13

Changing Line Voltage................................................................................. 13

Modular-Level Maintenance............................................................................. 14

Disassembly.................................................................................................. 15

Reassembly ................................................................................................... 15

Output Block Subassembly Connections.................................................. 17

Keypad to Main PCB................................................................................ 19

Display Assembly to Main PCB............................................................... 19

Opto RS232 to Main PCA........................................................................ 20

Reinstalling the Circuit Boards................................................................. 21

Connecting the Power Module ................................................................. 21

Final Assembly and Inspection..................................................................... 22

Performance Tests............................................................................................. 23

Required Equipment List.............................................................................. 23

Testing DC Voltage....................................................................................... 24

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525A

Service Manual

Testing DC Current....................................................................................... 25

Testing Thermocouple Output...................................................................... 26

Testing CJC (Cold Junction Compensation)............................................. 27

CJC (Cold Junction Compensation) Calibration....................................... 27

Testing Thermocouple Input......................................................................... 28

Testing Ohms Output.................................................................................... 29

Testing Ohms Input....................................................................................... 30

Testing Pressure Modules............................................................................. 32

Calibration Adjustment ..................................................................................... 32

Initiating Communication............................................................................. 32

Starting Adjustment Mode............................................................................ 32

Adjustment Sequence.................................................................................... 33

14: Calibrate DAC, Digital to Analog Converter Adjustment.................. 34

1: 100 mV Source to 4: 100 V Source, Adjusting DC Source.................. 34

5: 100 mA Source, Adjusting DC Current Source.................................... 35

6: Hi Ohms Source, Adjusting High Resistance Source........................... 37

7: Low Ohms, Adjusting Low Ohms Source............................................ 38

8: Hi Ohms, Adjusting High Resistance Measure.................................... 38

9: Low Ohms, Adjusting Low Resistance Measure.................................. 40

10: SPRT 25, Adjusting SPRT Low Resistance Measure ........................ 41

11: TC SOURCE, Adjusting TC mVolt Source....................................... 43

12: TC Read, Adjusting TC mVolt Measure............................................ 43

Customer Replaceable Parts.............................................................................. 45

Page 5

List of Tables

Table Title Page

1. Symbols Used on the Calibrator............................................................................ 2

2. Replacement Fuses ................................................................................................ 13

3. Front Panel Wire Color Assignments.................................................................... 16

4. Rear Panel Wire Color Assignments ..................................................................... 16

5. Output Block to Main PCA Connections............................................................... 17

6. TC PCA to Main PCA Connections...................................................................... 18

7. Opto RS232 to Main PCA Connections................................................................ 20

8. Power Module to Main PCA Connections............................................................. 21

9. Power Connections................................................................................................ 22

10. Required Equipment.............................................................................................. 23

11. Testing DC Voltage............................................................................................... 24

13. TC Temperatures ................................................................................................... 26

14. Ohms Output Ranges............................................................................................. 29

15. Ohms Ratio Table.................................................................................................. 31

16. Calibration Dependencies...................................................................................... 33

17. List of Equipment for Voltage Calibration Adjustments....................................... 34

18. List of Equipment for Current Calibration Adjustments ....................................... 35

19. List of Equipment for High Ohms Measure Calibration Adjustments .................. 38

20. List of Equipment for High Ohms Measure Calibration Adjustments .................. 40

21. List of Equipment for Low Ohms Measure Calibration Adjustments................... 41

22. List of Test Equipment for Adjusting TC Source.................................................. 43

23. List of Test Equipment for Adjusting TC Read..................................................... 43

24. List of Test Equipment for Adjusting TC CJC...................................................... 45

25. Replacement Parts.................................................................................................. 47

26. Accessories............................................................................................................ 48

iii

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525A

Service Manual

Page 7

List of Figures

Figure Title Page

1. Accessing the Fuse................................................................................................. 14

2. Wiring Connections............................................................................................... 17

3. Solder Connections for the TC PCA...................................................................... 18

4. Keypad PCA Connections..................................................................................... 19

5. Connections for the Opto RS232 PCA.................................................................. 20

6. Power Module Connections................................................................................... 22

7. Measuring DC Current........................................................................................... 25

8. Testing TC Output................................................................................................. 26

9. Connections for CJC Calibration........................................................................... 27

10. Connections for Measuring TC Input.................................................................... 28

11. Connection for Measuring Resistance Output....................................................... 29

12. 1281 Connection Diagram..................................................................................... 30

13. Connection for Measuring Ohms........................................................................... 31

14. Exploded View of the 525A .................................................................................. 46

Page 8

525A

Service Manual

Page 9

Introduction

This manual provides user-service information for the 525A Temperature/Pressure Calibrator (hereafter referred to as "the Calibrator"). Details regarding verification of the Calibrator’s functionality and calibration, basic maintenance, contacting Fluke service centers, and important safety information are also contained within this manual.

Contacting Fluke

To contact Fluke, order accessories, or locate the nearest Fluke Service Center or distributor, call:

• 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

525A

Or, visit Fluke’s Web site at www.fluke.com.

Safety Information

The Calibrator complies with EN 61010, ANSI/ISA-S82.01-1994, and CAN/CSA-C22.2 No. 1010.1-92. Use the Calibrator only as specified in this manual, otherwise the protection provided by the Calibrator may be impaired.

CAT II equipment is designed to protect against transients from energy-consuming equipment supplied from a fixed installation, such as televisions, personal computers, portable tools, and other household appliances.

A “WWarning” statement identifie s hazardous conditions and actions that could cause bodily harm or death.

A “WCaution” statement identifies conditions and actions that could damage the Calibrator or the equipment under test.

International symbols used on the Calibrator and in this manual are explained in Table 1.

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525A

Service Manual

WWarning

To avoid possible electric shock or personal injury, follow these guidelines:

Use the Calibrator only as specified in this manual or the protection provided by the

•

Calibrator might be impaired. Inspect the Calibrator before use. Do not use the Calibrator if it appears damaged.

•

Look for cracks or missing plastic. Pay particular attention to the insulation around the connectors.

Have the Calibrator serviced only by qualified service personnel.

•

Do not apply more than the rated voltage between the terminals, as marked on the

•

Calibrator, or between any terminal and earth ground. Always use the power cord and connector appropriate for the voltage and outlet of

•

the country or location in which you are working. Never operate the Calibrator with the cover removed or the case open.

•

Never remove the cover or open the case of the Calibrator without first removing the

•

power source. Use caution when working with voltages above 30 V ac rms, 42 V ac peak, or

•

60 V dc. These voltages pose a shock hazard. Use only the replacement fuse(s) specified in this manual.

•

Use the proper terminals, function, and range for your measurements.

•

Do not operate the Calibrator around explosive gas, vapor, or dust.

•

• When servicing the Calibrator, use only specified replacement parts.

Table 1. Symbols Used on the Calibrator

AC (Alternating Current) DC (Direct Current)

Pressure Chassis protective ground

Important Information. Refer to the manual.

Caution, risk of electric shock

Ω

Earth ground Resistance

Conforms to European Union directives Canadian Standards Association,

NRTL International ON/OFF symbol.

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Calibrator Specifications

General Specifications

Warm up time Twice the time since last warmed up, to a maximum of 30 minutes Settling time Less than 5 seconds for all functions and ranges except as noted Standard interface RS-232 Optional interface IEEE-488 (GPIB) Temperature performance

Electromagnetic compatibility CE: Conforms to EN61326 Temperature coefficient Temperature coefficient for temperatures outside tcal ±5 °C is

Relative humidity

Altitude Operating 3,050 m (10,000 ft) maximum

Safety

Analog low isolation 20 V Line power Line Voltage (selectable) 100 V/120 V or 220 V/240 V

Power consumption 15 VA maximum Dimensions Height 13.3 cm (5.25 in) plus 1.5 cm (0.6 in) four feet on bottom

Weight (without options) 4 kg (9 lb)

Operating 0 °C to 50 °C Calibration (tcal) 18 °C to 28 °C Storage -20 °C to 70 °C

10 % of the 90 day specification (or 1 year if applicable) per °C Operating < 80 % to 30 °C, < 70 % to 40 °C, < 40 % to 50 °C

Storage < 95 % noncondensing

Nonoperating 12,200 m (40,000 ft) maximum EN 61010 Second, ANSI/ISA-S82.01-1994,

CAN/CSA-C22.2 No. 1010.1-92, NRTL

Line Frequency 47 to 63 Hz Line Voltage Variation ±10 % about line voltage setting

Width ¾ standard rack width

Depth 47.3 cm (18.6 in) overall

525A

Calibrator Specification s

Page 12

525A

Service Manual

DC Voltage Specifications, Output

Absolute Uncertainty,

tcal ±5 °C

± (ppm of output +µV) Stability

Maximum

Burden

Ranges

90 days 1 year

± (ppm of output +µV)

Resolution

24 hours, ±1 °C

0 to 100.000 mV 25 3 30 3 5 +2 1 µV 10 mA 0 to 1.00000 V 25 20 30 20 4 +20 10 µV 10 mA 0 to 10.0000 V 25 200 30 200 4 +200 100 µV 10 mA 0 to 100.000 V 25 2 mV 30 2 mV 5 +1 mV 1 mV 1 mA

1. All outputs are positive only.

2. Remote sensing is not provided. Output resistance is < 1Ω.

Noise

Ranges

Bandwidth 0.1 to 10 Hz

(ppm of output +µV p-p)

Bandwidth10 Hz to 10 kHz

(µV rms)

0 to 100.000 mV 1 µV6 µV 0 to 1.00000 V 10 µV 60 µV 0 to 10.0000 V 100 µV 600 µV 0 to 100.000 V 10 ppm+1 mV 20 mV

DC Current Specifications, Output

Ranges

Absolute Uncertainty,

tcal ±5 °C

90 days 1 year

± (ppm of output +µA)

Resolution

Maximum

Compliance

Voltage

0 to 100.000 mA 85 2 100 2 1 µA 10 V 100 µH

1. All outputs are positive only.

Noise

Ranges

Bandwidth

0.1 to 10 Hz p-p

Bandwidth

10 Hz to 10 kHz rms

0 to 100.000 mA 2000 nA 20 µA

Maximum

Inductive

Load

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Calibrator Specification s

Resistance Specifications, Output

Absolute Uncertainty,

tcal ±5 °C,

Ranges

5 to 400.00 Ω 0.025 0.03 0.01 Ω 1 to 10 mA 5 to 4.0000 kΩ 0.25 0.3 0.1 Ω 250 µA to 1 mA

1. Continuously variable from 0 to 4 kΩ.

±(ppm of output ± Ω)

Resolution Allowable Current

90 days 1 year

525A

2. For currents lower than shown, the floor adder increases by Floor

(new)

= Floor

(old)

x I

min/Iactual

For example, a 500 µA stimulus measuring 100 Ω has a floor uncertainty of 0.025 Ω x 1 mA/500 µA =

0.05 Ω.

Resistance Specifications, Input

Absolute Uncertainty,

tcal ±5 °C, ±(ppm of output ± Ω)

Ranges

0 to 400.00 Ω 35 0.003 40 0.003 0.001 Ω 1 mA

401 to 4001.00 Ω 35 0.03 40 0.03 0.01 Ω 0.1 mA

90 days 1 year

Resolution Stimulus Current

Page 14

525A

Service Manual

Thermocouple Specification, Output and Input

Range (°C)

TC Type

B 600 °C

C0 °C

E -250 °C

J -210 °C

K -200 °C

L -200 °C

N -200 °C

1. Does not include thermocouple wire error.

Minimum Maximum 90 days 1 year

800 °C 1000 °C 1550 °C

150 °C 650 °C 1000 °C 1800 °C

-100 °C

-25 °C 350 °C 650 °C

-100 °C

-30 °C 150 °C 760 °C

-100 °C

-25 °C 120 °C 1000 °C

-100 °C 800 °C

-100 °C

-25 °C 120 °C 410 °C

800 °C 1000 °C 1550 °C 1820 °C

150 °C 650 °C 1000 °C 1800 °C 2316 °C

-100 °C

-25 °C 350 °C 650 °C 1000 °C

-100 °C

-30 °C 150 °C 760 °C 1200 °C

-100 °C

-25 °C 120 °C 1000 °C 1372 °C

-100 °C 800 °C 900 °C

-100 °C

-25 °C 120 °C 410 °C 1300 °C

Absolute Uncertainty,

tcal ±5 °C, ±(°C)

Output/Input

0.42 °C

0.39 °C

0.40 °C

0.44 °C

0.25 °C

0.21 °C

0.23 °C

0.38 °C

0.63 °C

0.38 °C

0.16 °C

0.14 °C

0.16 °C

0.20 °C

0.18 °C

0.14 °C

0.18 °C

0.25 °C

0.19 °C

0.14 °C

0.19 °C

0.30 °C

0.37 °C

0.26 °C

0.17 °C

0.33 °C

0.20 °C

0.16 °C

0.14 °C

0.21 °C

0.46 °C

0.39 °C

0.40 °C

0.45 °C

0.30 °C

0.26 °C

0.31 °C

0.50 °C

0.84 °C

0.50 °C

0.18 °C

0.15 °C

0.16 °C

0.21 °C

0.27 °C

0.20 °C

0.16 °C

0.17 °C

0.23 °C

0.33 °C

0.22 °C

0.16 °C

0.26 °C

0.40 °C

0.37 °C

0.26 °C

0.17 °C

0.40 °C

0.24 °C

0.19 °C

0.18 °C

0.27 °C

Page 15

Thermocouple Specification, Output and Input (continued)

525A

Calibrator Specification s

Range (°C)

TC Type

R0 °C

S0 °C

T -250 °C

U -200 °C

mV -10 to 75.000 mV

1. Does not include thermocouple wire error.

Minimum Maximum 90 days 1 year

250 °C 400 °C 1000 °C

250 °C 1000 °C 1400 °C

-150 °C 0 °C 120 °C

0 °C

250 °C 400 °C 1000 °C 1750 °C

250 °C 1000 °C 1400 °C 1750 °C

-150 °C 0 °C 120 °C 400 °C

0 °C 600 °C

Absolute Uncertainty,

tcal ±5 °C, ±(°C)

Output/Input

0.58 °C

0.34 °C

0.31 °C

0.30 °C

0.56 °C

0.36 °C

0.30 °C

0.35 °C

0.51 °C

0.18 °C

0.13 °C

0.12 °C

0.56 °C

0.27 °C

0.58 °C

0.35 °C

0.33 °C

0.40 °C

0.56 °C

0.36 °C

0.37 °C

0.46 °C

0.63 °C

0.24 °C

0.16 °C

0.14 °C

0.56 °C

0.27 °C

TC mV Specifications, Input and Output

Absolute Uncertainty,

tcal +/-5 °C

+/-( ppm of output + µV)

Range

(mV)

-10 to

75.000

90 Days 1 Year

25 + 3µV 30 + 3µV5 + 2µV1µV 10 Ohms

+/- ( ppm of output + µV) Resolution

Stability

24 Hours +/-1°C

Maximum

Burden

Page 16

525A

Service Manual

RTD and Thermistor Specification, Output

RTD Type

Pt 385, 100 Ω -200 °C

Pt 3926, 100 Ω -200 °C

Pt 3916, 100 Ω -200 °C

Minimum Maximum 90 days 1 year

-80 °C 0 °C 100 °C 300 °C 400 °C 630 °C

-80 °C 0 °C 100 °C 300 °C 400 °C

-190 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C

Range (°C)

-80 °C 0 °C 100 °C 300 °C 400 °C 630 °C 800 °C

-80 °C 0 °C 100 °C 300 °C 400 °C 630 °C

-190 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C 630 °C

Absolute Uncertainty

tcal ±5 °C, ±(°C)

0.06 °C

0.08 °C

0.07 °C

0.08 °C

0.06 °C

0.07 °C

0.08 °C

0.06 °C

0.07 °C

0.08 °C

0.07 °C

0.10 °C

0.09 °C

0.10 °C

0.07 °C

0.08 °C

0.09 °C

0.07 °C

0.08 °C

0.09 °C

Pt 385, 200 Ω -200 °C

Pt 385, 500 Ω -200 °C

1. 2-wire output

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C 630 °C

0.31 °C

0.32 °C

0.33 °C

0.36 °C

0.42 °C

0.13 °C

0.14 °C

0.15 °C

0.16 °C

0.38 °C

0.39 °C

0.43 °C

0.50 °C

0.15 °C

0.16 °C

0.17 °C

0.18 °C

0.19 °C

Page 17

RTD and Thermistor Specification, Output (continued)

525A

Calibrator Specification s

Absolute Uncertainty

RTD Type

Minimum Maximum 90 days 1 year

Pt 385, 1000 Ω -200 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C

PtNi 385, 120 Ω (Ni 120)

-80 °C 0 °C 100 °C

Cu 427, 10 Ω

-100 °C 260 °C 0.63 °C 0.75 °C

Range (°C)

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C 630 °C

0 °C 100 °C 260 °C

0.06 °C

0.07 °C

0.08 °C

0.04 °C

0.03 °C

tcal ±5 °C, ±(°C)

YSI 400 15 °C 50 °C 0.005 °C 0.007 °C

1. 2-wire output

2. Based on MINCO Application Aid No. 18.

RTD and Thermistor Specification, Input

Absolute Uncertainty,

RTD Type

Range (°C)

Minimum Maximum 90 days 1 year

tcal ±5 °C, ±(°C)

0.07 °C

0.08 °C

0.09 °C

0.05 °C

0.04 °C

0.03 °C

Pt 385, 100 Ω -200 °C

-80 °C 0 °C 100 °C 300 °C 400 °C 630 °C

Pt 3926, 100 Ω -200 °C

-80 °C 0 °C 100 °C 300 °C 400 °C

Pt 3916, 100 Ω -200 °C

-190 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C

Pt 385, 200 Ω

-200 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C

-80 °C 0 °C 100 °C 300 °C 400 °C 630 °C 800 °C

-80 °C 0 °C 100 °C 300 °C 400 °C 630 °C

-190 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C 630 °C

1. 4-wire mode. Uncertainties listed do not include probe uncertainties.

0.031 °C

0.018 °C

0.027 °C

0.031 °C

0.042 °C

0.050 °C

0.031 °C

0.014 °C

0.018 °C

0.026 °C

0.031 °C

0.041 °C

0.026 °C

0.011 °C

0.014 °C

0.018 °C

0.025 °C

0.026 °C

0.031 °C

0.040 °C

0.042 °C

0.071 °C

0.075 °C

0.079 °C

0.082 °C

0.090 °C

0.093 °C

0.100 °C

0.101 °C

0.012 °C

0.020 °C

0.030 °C

0.035 °C

0.047 °C

0.057 °C

0.031 °C

0.015 °C

0.019 °C

0.029 °C

0.034 °C

0.046 °C

0.028 °C

0.012 °C

0.015 °C

0.019 °C

0.028 °C

0.029 °C

0.034 °C

0.045 °C

0.047 °C

0.072 °C

0.076 °C

0.081 °C

0.085 °C

0.093 °C

0.097 °C

0.105 °C

0.106 °C

Page 18

525A

Service Manual

RTD and Thermistor Specification, Input (continued)

RTD Type

Minimum Maximum 90 days 1 year

Pt 385, 500 Ω -200 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C

Pt 385, 1000 Ω -200 °C

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C

PtNi 385, 120 Ω (Ni120)

-80 °C 0 °C 100 °C

Cu 427, 10 Ω

-100 °C 260 °C 0.300 °C 0.069 °C

Range (°C)

-80 °C 0 °C 100 °C 260 °C 300 °C 400 °C 600 °C 630 °C

0 °C 100 °C 260 °C

Absolute Uncertainty,

tcal ±5 °C, ±(°C)

0.046 °C

0.049 °C

0.043 °C

0.030 °C

0.032 °C

0.037 °C

0.047 °C

0.048 °C

0.031 °C

0.034 °C

0.039 °C

0.025 °C

0.027 °C

0.030 °C

0.041 °C

0.042 °C

0.209 °C

0.210 °C

0.211 °C

0.047 °C

0.050 °C

0.045 °C

0.033 °C

0.035 °C

0.041 °C

0.052 °C

0.076 °C

0.032 °C

0.035 °C

0.040 °C

0.028 °C

0.030 °C

0.034 °C

0.045 °C

0.047 °C

0.210 °C

0.211 °C

0.212 °C

YSI 400 15 °C 50 °C 0.005 °C 0.304 °C SPRT, 25 Ω User Defined User Defined 0.05 °C 0.06 °C

1. 4-wire mode. Uncertainties listed do not include probe uncertainties.

2. Based on MINCO Application Aid No. 18.

Page 19

Pressure Measurement

The Calibrator can accept either the Fluke 700 or 6100 series pressure modules. Pressure modules plug directly into the front panel Lemo connector. The Calibrator firmware automatically detects the type and value of the module you are attaching, and recognizes the following units of measurement:

• PSI (pounds per square inch)

• inH2O4°C (inches of water at 4 degrees Celsius)

• inH2O20C (inches of water at 20 degrees Celsius)

• cmH2O4°C (centimeters of water at 4 degrees Celsius)

• cmH2O20C (centimeters of water at 20 degrees Celsius)

• BAR (bars)

525A

Theory of Operation

• mBAR (millibars)

• KPAL (kilopascals)

• inHG 0°C (inches of mercury at 0 degrees Celsius)

• mmHG 0°C (millimeters of mercury at 0 degrees Celsius)

• Kg/cm2 (kilograms per square centimeter)

Theory of Operation

The Calibrator serves as an accurate laboratory device for calibrating thermocouples, RTDs, pressure devices, and low-level dc voltages and currents. The main PCB assembly, and several subassemblies, work together to provide high-reliability and easy maintenance.

Micro-Controller Section

The Atmel ATmega 103 micro-controller is the heart of the 525A. It contains all of the program memory, nv-ram, FlashROM, static RAM, and EEProm. The micro-controller allows a minimal amount of external glue logic. The main external digital ICs are the RS232 driver, relay drivers, LCD controller, and the digitally controlled analog switches. Many of the ICs are interfaced through the micro-controller’s three-wire SPI bus minimizing interconnecting lines. Inputs or outputs begin with instructions entered through the keypad or through remote communications (serial or IEEE-488) into the micro-controller. The micro-controller processes the commands and sets conditions that are appropriate for the command.

Page 20

525A

Service Manual

Analog Section

The Calibrator can source DC voltage to 100 V, DC current to 100 mA, resistances from 5 to 4000 Ω, and thermocouples and RTDs. The main components of the analog circuit consist of a precision 2.5-volt temperature compensated reference, 20-bit DAC and a 24-bit ADC. Precision metal foil resistor networks and several chopper-stabilized OP-AMPS are the most critical analog components.

When sourcing, the micro-controller, using stored calibration constants, adjusts the D/A to generate an output based on the function and range selected. To achieve high accuracy, a low drift 24-bit A/D converter is used as a feedback element near the output of the D/A converter. The scaled output DAC_CK is routed to the A/D converter.

In the input mode, the A/D is used directly to measure either the T/C or the resistance (RTD) inputs. The A/D features an internal self-calibration function that continually nulls out zero drift due to temperature changes. A programmable gain stage in the A/D is adjusted by the microcontroller to allow direct T/C and RTD inputs without requiring external amplification. In the RTD mode, a constant current source is used to excite the RTD and the voltage developed across the RTD is measured by the A/D, then the resistance can be calculated.

Basic Maintenance

To avoid personal injury or damage to the Calibrator, use only the specified replacement parts and do not allow water into the case.

Cleaning the Calibrator

To avoid damaging the case, do not use solvents or abrasive cleaners.

Clean the Calibrator and pressure modules with a soft cloth dampened with water or mild soap and water.

Replacing a Line Fuse

To avoid electrical shock, disconnect line power before opening the case or line voltage selector.

The line power fuses and line voltage selector switch are located in a compartment above the power switch on the right rear of the Calibrator. The fuse-rating label on the rear panel shows the correct replacement fuse for each line voltage setting.

W Warning

WCaution

W Warning

Table 2 lists the fuse part numbers for each line voltage setting. Figure 1 shows how to remove the fuse compartment cover.

Page 21

To Check or Replace a Fuse

1. Disconnect line power.

2. Using a flat-blade screwdriver, pry the tab at the base of the line fuse compartment.

The compartment cover will pop part way out.

3. Remove the compartment cover. The fuses come out with the compartment cover and

can easily be checked or replaced.

4. To reinstall the fuse, push the compartment cover back into the compartment until the

tab locks in place.

Note

When changing the line voltage setting, make sure to verif y that the appropriate line fuse is installed in the Calibrator. Replace the fuse as required.

Table 2. Replacement Fuses

Part Number Fuse Description Line Voltage Setting

1645311 W Fuse, 0.25 A fast fuse 120 V (90 V to 132 V)

525A

Basic Maintenance

1645327 W Fuse, 0.125 A fast fuse 240 V (198 V to 264 V)

Changing Line Voltage

The Calibrator arrives from the factory configured for the line voltage appropriate for the country of purchase or as specified when it is ordered. To verify the line voltage setting, check the line voltage indicator on the line power fuse compartment cover.

Note

Confirm that the line voltage selection is set for 120 V for line voltages between 90 V and 132 V or that the selector is set to 240 V for line voltages between 198 V and 264 V.

To change the line voltage:

1. Disconnect line power.

2. Using a flat-blade screwdriver, pry the tab at the base of the line fuse compartment.

The compartment cover will pop part way out.

3. Remove the compartment cover.

4. Remove the line voltage selector assembly by gripping the line voltage indicator tab

with pliers and pulling it straight out of the compartment.

5. Rotate the line voltage selector assembly to the desired voltage and reinsert.

6. Verify the appropriate fuse is being used for the selected line voltage (see Table 2)

and reinstall the fuse compartment by pushing it in unt il the tab lock s in place.

Page 22

525A

Service Manual

Line voltage indicator

Changing

line fuse

Line fuse

compartment

(SB)

Figure 1. Accessing the Fuse

Modular-Level Maintenance

XWarning

Do not attempt to complete the following procedures unless qualified to do so. This information is for use by qualified personnel only.

When making solder connections, use "no clean" solder.

120

Changing line

voltage

WCaution

240V

120V

Rotate to change

line voltage indicator

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At some point in time, it may be necessary to perform modular-level maintenance or troubleshooting of the Calibrator.

Page 23

Evaluation of most problems can be made after the top cover is removed. Inside the chassis are six circuit boards. They are connected to one another with point to point wiring. The six circuit boards are the Main PCA, Keypad PCA, TC PCA, Lemo PCA, Opto RS232 PCA, and the Display PCA.

Most of the Calibrator circuitry is located on the Main PCA. The Display PCA, Keypad PCA, and Lemo PCA are mounted to the front of the chassis. The TC PCA is mounted in the Output Block, and the Opto RS232 PCA is mounted on the rear of the chassis.

If the Main PCA needs repair, it is recommended that all other circuit boards be removed from the chassis still assembled. Repair of the other circuit boards can be accomplished while leaving them inside the cha ssis.

Disassembly

To open the Calibrator case, remove the six screws from each end and lift off the top cover.

To remove all of the circuit boards while still assembled, do the following:

1. Stand the chassis on the front handles.

2. Remove the four nylon screws that attach the Display PCA to the front.

525A

Modular-Level Maintenance

3. Remove the six screws that attach the Keypad PCA to the front.

4. Remove the five nuts that attach the Output Block to the front.

5. Remove the standoff nuts from the 9-pin D connector on the Opto RS232 PCA, if

present.

6. Stand the 525A back on its feet.

7. Remove the screws attaching the Opto RS232 PCA to the back, if present.

8. Remove the four screws through the transformer.

9. Remove the six screws that attach the Main PCA to the chassis base.

10. Carefully lift all of the attached circuit boards out of the chassis.

Reassembly

It is easier to solder the wires interconnecting the circuit boards before placing the assemblies back into the chassis. The procedures in this section will explain how to reconnect each of the circuit boards.

There are two wire sets available from Fluke. These wire sets are used to connect the circuit boards. One set is for the front connections and the other set is for the rea r panel connections. Refer to Figure 2 for wire locations and Tables 3 and 4 for the detailed list of front and rear panel connections.

Page 24

525A

Service Manual

Table 3. Front Panel Wire Color Assignments

Wire Number Color

J5 Red 24 g Wire J7 Black 24 g Wire J16 Purple 20 g Wire * J 17 Grey 20 g Wire * J18 (1st 6 inches) Red 20 g Wire * J19 Black 20 g Wire * J20 Blue 20 g Wire * J21 Yellow 20 g Wire * J22 (2nd six inches) Red 20 g Wire * J33 White/Red 20 g Wire * J34 Green 20 g Wire *

(all lengths are 6 inches)

Gage

J35 White 20 g Wire * J36 Black/Red 20 g Wire * * Connect With Terminal Lug

Table 4. Rear Panel Wire Color Assignments

Wire Number Color

AC3 Red 20 g Wire* AC4 White 20 g Wire* AC7 Red 20 g Wire * AC8 Green 20 g Wire * AC9 Black 20 g Wire * AC10 White 20 g Wire * * Connect With Spade Lug

(all lengths are 6 inches)

Gage

Page 25

Ribbon wire

525A

Modular-Level Maintenance

Purple wire

Yellow wire

Blue wire

Red wire

Yellow wire

Blue wire

Figure 2. Wiring Connections

Grey wire

Purple wire

Red wires

Output Block Subassembly Connections

Table 5 lists the connections to be made when connecting the Output Block to the Main PCA. Use 8-32 low thermal nuts and 8-32 low thermal washers for these connections.

Table 5. Output Block to Main PCA Connections

Wire Color Connect From Connect To

Blue J20 RTD HI

Green wire

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Yellow J21 RTD LO Purple J16 mA HI Grey J17 mA LO Green J34 4 W RTD Sense HI White J35 4 W RTD Sense LO Red (2 wires) J18 & J22 one leg of the 0.1 µF Cap Volts Hi Black J19 the other leg of the 0.1 µF Cap Volts LO Black with red stripe J33 4 W RTD HI White with red stripe J36 4 W RTD LO

Page 26

525A

Service Manual

The TC PCA needs to be connected to the Main PCA. Use the wire connections listed in Table 6. These connections require soldering. Refer to Figure 3.

Table 6. TC PCA to Main PCA Connections

Solder From TC PCA

Wire Color

Red 1st wire pad J23 Black 2nd wire pad J24 Blue 3rd wire pad J25 Yellow 4th wire pad J26 White 5th wire pad J27 Purple 6th wire pad J28

(from left to right) Solder To Main PCA

Blue wire

Yellow wire

Purple wire

Red wire

Ribbon cable

Figure 3. Solder Connections for the TC PCA

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Page 27

Keypad PCA to Main PCA

To connect the Keypad PCA to the Main PCA, solder the following connections (refer to Figure 4):

1. Solder the 12-conductor cable to the back of the Keypad PCA with pin 1 on the cable

aligned with pin 1 on the Keypad PCA.

2. Solder the Keypad ribbon cable to J11 with pin 1 lined up with the square hole in

J11.

525A

Modular-Level Maintenance

Figure 4. Keypad PCA Connections

Display Assembly to Main PCA

To attach the Display Assembly to the Main PCA, make the following connections:

1. Solder a red wire from J5 on the Main PCA to the "A" hole in the Display PCA.

2. Solder a black wire from J7 on the Main PCA to the "K" hole in the Display PCA.

3. Solder the 14-connector cable to the back of the Display PCA with pin 1 on the cable

aligned with pin 1 on the Display PCA.

4. Solder the 14-conductor ribbon cable to the LCD Display (J4) position on the right

side of the Main PCA with pin 1 in the square hole in J4.

Ribbon cables

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Page 28

525A

Service Manual

Opto RS232 PCA to Main PCA

Use 4 wires to connect the Opto RS232 PCA to the Main PCA. Refer to Table 7 and Figure 5.

Table 7. Opto RS232 to Main PCA Connections

Main PCA Opto RS232

J38, pin 2 J1, pin 2 J38, pin 3 J1, pin 3 J38, pin 5 J1, pin 5 J63 J1, pin 4

After completing this task, the circuit board assembly is ready to reinstall into the chassis.

Red wire

Figure 5. Connections for the Opto RS232 PCA

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Page 29

Reinstalling the Circuit Boards

1. Place the Main PCA with all its attachments into the chassis base.

2. Put the Output Block into place in the front of the chassis.

3. Use five nylock nuts to secure the Output Block to the Chassis Base.

4. Lay the Main PCA down so that it is in place.

5. Use the (6) 6-32 5/8" screws and (6) lock washers to secure the Main PCA to the

chassis base.

6. Use the (4) 6-32 X-former screws and (4) #6 nylon washers to secure the transformer

to the chassis.

7. Using the (2) jack standoffs, attach the Opto RS232 PCA to the rear of the chassis.

8. Stand the unit on its front handles.

9. Insert the keypad into the front of the chassis.

10. Use (6) 6-32 x 3/8" screws to attach the Keypad PCA to the chassis base.

11. Remove the protective plastic from the LCD and put it over the lens on the front label

(outside).

12. Use the (4) 6-32 nylon screws and the 4 nylon washers to attach the Display PCA to

the chassis. The washers go between the Display PCA and the chassis base.

525A

Modular-Level Maintenance

Connecting the Power Module

To attach the Power Module to the Main PCA, make the connections listed in Table 8. Refer to Figure 6.

Table 8. Power Module to Main PCA Connections

Wire Color From To

Red AC3 Terminal 3 on Power Module White AC4 Terminal 4 on Power Module Red AC7 Terminal 7 on Power Module Green AC8 Terminal 8 on Power Module Black AC9 Terminal 9 on Power Module White AC10 Terminal 10 on Power Module

Page 30

525A

Service Manual

Red wires

Green wire

Top view

Red wires

Green wire

Figure 6. Power Module Connections

Final Assembly and Inspection

To complete final assembly and inspection, use a digital multimeter and verify the continuity of the connections listed in Table 9.

Table 9. Power Connections

Wire Color Position B Position on Main PCA

Red Power Module Pin 3 AC3 White Power Module Pin 4 AC4 Red Power Module Pin 7 AC7 Green Power Module Pin 8 AC8 Black Power Module Pin 9 AC9 White Power Module Pin 10 AC10 Red J5 LCD J2 A Black J7 LCD J2 K

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White J62 Opto Pin 4 N/A J52 Inside Chassis Base (no connection)

Install tie wraps around the AC wires, the Output Block wires, the LCD backlight wires, the 5-conductor cable, and the Opto-RS232 wires.

Page 31

Performance Tests

The following performance tests are used to verify the functionality of the Calibrator. If the Calibrator fails any part of the performance tests, calibration adjustment or repair by a Fluke Service Center is in order. For a list of service centers, refer to "Contacting Fluke" earlier in this manual.

Required Equipment List

To complete the performance tests and calibration adjustment, the equipment listed in Table 10 is necessary. If the equipment listed is not available, equipment with the same or better specifications can be substituted.

Table 10. Required Equipment

Manufacturer Model Equipment Purpose

Fluke Fluke- 525A/Leads Test Lead Set All Functions

525A

Performance Tests

Fluke 742A-10 Resistance

Standard, 10 Ω

Fluke 742A-100 Resistance

Standard, 100 Ω

Fluke 742A-10K Resistance

Standard, 10K Ω

Fluke 5520A Calibrator Low Ohms Measure and SPRT

Wavetek 1281 DMM All functions except CJC _ _ Ohms Shorting

Block

_ _ RTD Probe TC CJC Calibration Hart Scientific 1521 Precision

Thermometer

Omega J Thermocouple

Probe

_ _ Lag Bath TC CJC Calibration

100 mA source calibration

Low Ohms Measure and SPRT Calibration.

Hi Ohms Measure Calibration

Calibration. Hi Ohms Measure Calibration.

Low Ohms Measure and SPRT Calibration. Hi Ohms Measure Calibration.

TC CJC Calibration

Dewar Flask with lid

Banana Jack to Copper TC MiniConnector Cable

TC tests

Page 32

525A

Service Manual

Testing DC Voltage

The DC voltage amplitude accuracy test verifi es the accu racy of DC volt age at the 525A calibrator front panel Volts Source output. See Table 11.

Table 11. Testing DC Voltage

Range

100 mV

1.0 V

10.0 V

100.0 V

Nominal

Value (V)

0 0.000003 0.000003

0.025 3.63E-06 3.75E-06

0.075 4.88E-06 5.25E-06

0.1 5.5E-06 0.000006 0 0.00002 0.00002

0.25 2.63E-05 2.75E-05

0.75 3.88E-05 4.25E-05 1 0.000045 0.00005 0 0.0002 0.0002

2.5 0.000263 0.000275

7.5 0.000388 0.000425 10 0.00045 0.0005 0 0.002 0.002 25 0.002625 0.00275

Measured

Value Deviation %

90 Day Spec.

(V)

One Year Spec. (V)

75 0.003875 0.00425 100 0.0045 0.005

Page 33

Testing DC Current

Use the Wavetek 1281 and the precision shunt to measure the 525A output as shown in Figure 7. Take the Voltage reading from the Wavetek 1281 and divide it by the 742A-1 actual value. See Table 12.

525A

Performance Tests

Current Shunt

OUTPUT

100V MA X

VOLTS

20V PK

MAX

INPUT

20V PK

MAX

TEMPERATURE / PRESSURE CALIBRATOR

525A

RTD

100mA MAX

4W RTD

SENSE

INPUT/OUTPUT

20V PK

525A

TC RTD

INPUTOUTPUT

ZERO

CJCSETUP

C / F

AUTOSET

LOCAL EXP

TYPE UNITS

SHIFT

ENTER

•

VOLTS

STBY OPR

MAX

SET RECALL

RNG LOCK

Output

Terminals

Figure 7. Measuring DC Current

Table 12. Measuring DC Current

742A-1

100 mA

Output (A) Volt

Current

(I=E/R)

Shunt

Value 90 Day (A) 1 Year (A)

0.000 Direct Into 1281 Input

1281 DCV Function

ajr25f.eps

0.000002 0.000002

0.025 0.0000041 0.0000045

0.075 0.0000083 0.0000095

0.100 0.0000105 0.000012

Page 34

525A

Service Manual

Testing Thermocouple Output

For this test the TC mV specifications will be used. When this test is combined with the CJC test, all functions of the TC output will have been checked. Typically, the cable needs to connect the 525A to the 1281 and will need to be fabricated. The TC miniconnector will need to be copper - copper (white). Using copper wire, connect the TC mini-connector to standard banana jacks. See Figure 8 for a connection diagram.

For this test, the CJC (cold junction compensation) must be turned off. Press I 5 to turn off the CJC. XCJC on the display indicates that the CJC is turned off. Select TC, and Output. Press Euntil mV/°C is shown on the display. Output the mV values listed in Table 13.

525A

TEMPERATURE / PRESSURE CALIBRATOR

525A

4W RTD

RTD

100mA MAX

SENSE

INPUT/OUTPUT

20V PK

MAX

VOLTS

STBY OPR

OUTPUT

SET RECALL

RNG LOCK

RTD

INPUT

ZERO

CJCSETUP

C / F

AUTOSET

LOCAL EX P

•

TYPE UNITS

SHIFT

ENTER

OUTPUT

100V M AX

20V PK

INPUT

20V PK

VOLTS

MAX

1281

Figure 8. Testing TC Output

Table 13. TC Temperatures

Nominal Voltage (mV) 90 Day Spec. (mV) 1 Year Spec. (mV)

-5.000 0.003125 0.00315

15.00 0.003375 0.00345

30.00 0.00375 0.0039

50.00 0.00425 0.0045

70.00 0.00475 0.0051

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Page 35

Testing CJC (Cold Junction Compensation)

Connect a Type-J thermocouple to the TC terminal on the 525A. Immerse the thermocouple and a precision thermometer into a mineral oil lag bath. The test set-up is shown in Figure 9.

Verify that the readings of the 525A and the precision thermometer are within the Type-J specifications:

• The 90 day spec is 0.14 °C

• The 1 year spec is 0.16 °C

Note

Typical Type-J thermocouples Do not have specifications accurate enough to be used as a standard. To maintain a good Test Uncertainty Ratio (TUR) a characterized Type-J thermocouple may need to be used.

CJC (Cold Junction Compensation) Calibration

Connect a Type-J thermocouple to the TC terminals on the Calibrator, and immerse the thermocouple and a precision thermometer in a mineral oil lag bath. The test setup is shown in Figure 9. Verify that the readings of the thermometer and the Calibrator are within the thermocouple specifications listed in the Specifications section.

525A

Performance Tests

OUTPUT

100V M AX

20V PK

INPUT

20V PK

VOLTS

MAX

TEMPERATURE / PRESSURE CALIBRATOR

525A

RTD

100mA MAX

4W RTD

SENSE

Thermocouple

INPUT/OUTPUT

20V PK

MAX

J type

525A

TC RTD

INPUT

ZERO

CJCSETUP

C / F

AUTOSET

LOCAL EXP

TYPE

UNITS

SHIFT

ENTER

•

VOLTS

STBY OPR

OUTPUT

SET RECALL

RNG LOCK

Mineral Oil

Lag Bath

Figure 9. Connections for CJC Calibration

Mercury Thermometer

Dewar Flask

and Cap

ajr22f.eps

Page 36

525A

Service Manual

Testing Thermocouple Input

Set the 525A to TC input by pressing I then 7. All other 525A conditions will be the same as the thermocouple output test, CJC off, mV/°C mode.

Connect the 525A to the 5520A as shown in Figure 10. Set the 5520A to output the mV values in Table 13.

525A

TEMPERATURE / PRESSURE CALIBRATOR

525A

4W RTD

RTD

100mA MAX

SENSE

INPUT/OUTPUT

20V PK

MAX

VOLTS

STBY OPR

OUTPUT

SET RECALL

RNG LOCK

RTD

INPUT

ZERO

CJCSETUP

C / F

AUTOSET

LOCAL EXP

TYPE

UNITS

SHIFT

ENTER

•

5520A Normal Output

DC Volts Function

OUTPUT

100V M AX

VOLTS

20V PK

MAX

INPUT

20V PK

MAX

Figure 10. Connections for Measuring TC Input

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Page 37

Testing Ohms Output

Use the precision digital multimeter (DMM) to measure the resistance output. Figure 11 shows the four-wire connections. See Table 14.

The Wavetek 1281 must be in the “loI” (low current mode) when measuring

Ω

in the 4 kΩ range or an overload will occur.

525A

TEMPERATURE / PRESSURE CALIBRATOR

525A

4W RTD

RTD

100mA MAX

SENSE

INPUT/OUTPUT

20V PK

MAX

OUTPUT

100V M AX

20V PK

VOLTS

MAX

INPUT

MAX

525A

Performance Tests

Note

VOLTS

STBY OPR

OUTPUT

SET RECALL

RNG LOCK

RTD

INPUT

ZERO

CJCSETUP

C / F

AUTOSET

LOCAL EXP

TYPE

UNITS

SHIFT

ENTER

•

1281 Ohms 4-wire Function

Figure 11. Connection for Measuring Resistance Output

Table 14. Ohms Output Ranges

Range (Ω) Output (Ω) 1 Year (Ω)

400

50.03 100 200 0.03 300 0.03 400 0.03

4000

50.3 1000 2000 0.3 3000 0.3 4000 0.3

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Page 38

525A

Service Manual

Testing Ohms Input

Before measuring ohms input, the ohms output of a 5520A must be “characterized”. To achieve the needed accuracy, the Wavetek 1281 is used as a transfer standa rd an d the 742A is used as the reference standard. To find the true value of the 5520A output, the ratio-input function of the Wavetek 1281 is used. The ratio function of the 1281 is located on the rear panel and is designated as Channel A and Channel B. Connect Channel A to the 742A and connect the 5520A to Channel B, both using four-wire measure. See Figure 12 for a connection diagram.

1281

Chan A

Pin Pin

Hi I I Lo

742

31 28 23 21 31 28 23 21

Figure 12. 1281 Connection Diagram

Rear inputs

Hi I I Lo

Chan B

5520A

ajr28f.eps

For the 400 Ω range use the 742A-1K and for the 4 kΩ range use the 742A-10K. For more information on the correct usage of ratio mode refer to the 1281 Operators Manua l. Use Table 15 to note the ratio indication on the 1281. Ignore the 0 Ω value. Use the formula (742A actual value/ratio indication * 100 = actual 5520A value) and enter that ohm value into the 5520A actual value column.

Page 39

Table 15. Ohms Ratio Table

525A

Performance Tests

5520A

Range

(Ω)

742A

Value

(Ω)Ratio

Actual

Value

(Ω)

525A

Reading Specification

90 Day

Specification

400

0 0.002 0.003 0.003 100 0.006 0.0065 0.007 200 0.01 0.010 0.011 300 0.014 0.0135 0.015 400 0.018 0.017 0.019

4000

0 0.02 0.03 0.03 1000 0.06 0.065 0.07 2000 0.1 0.10 0.11 3000 0.14 0.135 0.15 4000 0.18 0.17 0.19

First apply a four wire short to the 525A 4W RTD Ohm input. Set the 525A to the 400 Ω range. Note the reading. Set the 525A to the 4000 Ω range. Note the reading. Move the 525A 4W RTD Ohm input to the output of the 5520A. Output the same nominal values and note the 525A readings in the 525A reading column. Subtract the actual 5520A value from the 525A reading and ensure that it is within the specified tolerance.

1 Year

Specification

OUTPUT

100V MA X

VOLTS

20V PK

MAX

INPUT

20V PK

MAX

TEMPERATURE / PRESSURE CALIBRATOR

525A

RTD

100mA MAX

4W RTD

SENSE

INPUT/OUTPUT

20V PK

525A

RTD

INPUT

ZERO

CJCSETUP

C / F

AUTOSET

LOCAL EXP

TYPE UNITS

SHIFT

ENTER

•

5520A 4

Function

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VOLTS

STBY OPR

MAX

OUTPUT

SET REC ALL

RNG LOCK

Figure 13. Connection for Measuring Ohms

Page 40

525A

Service Manual

Testing Pressure Modules

Calibration Adjustment

Initiating Communication

The Fluke 700 series pressure modules are calibrated separately from the 525A. The calibration follows the pressure module, so only a performance test is needed. Connect any of the Fluke 700 series pressure modules to the pressure module connector. Verify that the Calibrator reads pressure.

Adjusting the Calibrator requires no mechanical adjustment. All adjustments are performed electronically. The calibration is performed via serial communications port. The adjustments take place over the normal RS232 interface. Refer to Table 6 for a list of required equipment for performing the following procedures. Note that the adjustment for the Resistance Measure was designed to be especially flexible, allowing for the use of fixed resistors.

Terminals can be set up using terminal communications software on a personal computer (PC). Connect a 9-pin null modem cable to the RS232 connector on the back of the Calibrator. Connect the other end of the cable to the PC/PC serial port. An adapter may be needed for terminals that use 25 pin D serial connectors. A terminal program such as Window HyperTerminal may be used in the PC.

The terminal settings need to be set as follows: Bits per second: 9600 Data bits: 8 Parity: None Stop bits: 1 Flow control: None Local echo: on

Starting Adjustment Mode

The Calibrator needs to warm up for at least 30 minutes before performing these procedures. This will allow any thermal changes in the Calibrator to stabilize. If the unit has been repaired or is new, it should be given 24 hours to burn in. To initiate the calibration mode, use the PC to send the CAL_START command. The following will be displayed on the PC:

Calibration is password protected Enter Password:

Page 41

Calibration Adjustment

The password is 525. Enter the password through the PC keyboard and the following is displayed on the PC monitor:

Calibration Menu: 1: 100 mV Source 2: 1 V Source 3: 10 V Source 4: 100 V Source 5: 100 mA Source 6: Hi Ohms Source 7: Low Ohms Source 8: Hi Ohms Measure 9: Low Ohms Measure 10: SPRT 25 11: TC SOURCE 12: TC READ 13: TC CJC 14: Calibrate DAC

Enter Selection:

525A

Adjustment Sequence

Manual calibration of the Calibrator is a menu driven process. The menu consists of 14 different menu selections for calibration of the different operating modes.

Certain functions must be calibrated before others. Table 16 lists the calibration dependencies and tells which functions are dependent on others being calibrated first. An X in a row indicates that the step in that column must be before the step in that row can be completed. These dependencies are only related to calibration adjustment. They are not intended to show the relationship between normal functionality and calibration.

Table 16. Calibration Dependencies

1234567891011121314

1N/A X 2N/A X 3N/A X 4N/A X 5N/A X 6N/A 7N/A 8N/A 9N/A 10 N/A 11 N/A X 12 XN/A X 13 XXN/AX 14 N/A

Page 42

525A

Service Manual

14: Calibrate DAC, Digital to Analog Converter Adjustment

1: 100 mV Source to 4: 100 V Source, Adjusting DC Source

If all of the functions that are affected by the digital to analog converter (DAC) adjustment are going to be adjusted, start with step 14 which adjusts the DAC. Do not adjust the DAC unless all of the ranges affected are going to be readjusted. During normal calibration adjustment, it is necessary to adjust the DAC. However, for example, if a mistake were made in the 100 V range, the user would not want to readjust the DAC. If it were readjusted, the user would have to readjust everything that depends on that range.

To adjust the calibration of the DAC from the menu, type 14 and then press the Enter key on the PC keyboard. No external connection is necessary. The DAC adjust will execute, save the calibration constants, then display the Calibration Menu on the PC.

Adjusting the voltage output breaks down into four distinct ranges; each can be adjusted separately using menu selections 1-4. The adjustments are done in 2 parts. The first part sets the 0 and span values. The second part is to fine adjust the zero, span, and adjusts the linearity. The example below is for the 1 V range. The other ranges use the same steps with different voltage values. Refer to Table 17 for a list of equipment used in this section.

Table 17. List of Equipment for Voltage Calibration Adjustments

Manufacturer Model Equipment

Fluke FLUKE-525A/LEADS Test Lead Set Wavetek 1281 DMM

1. Connect the calibrator VOLTS HI and LO to the DMM input.

2. Set the DMM to DC Volts.

3. Type 2 and push the Enter key on the PC. The following is displayed on the PC:

First Calibration Point. Enter the Volts displayed:

4. When the reading on the DMM stabilizes, type the reading value on the PC and press

Enter. After the value has been entered, the following is displayed on the PC:

Second Calibration Point. Enter the Volts displayed:

5. When the reading on the DMM stabilizes, type the reading value on the PC and press

Enter. After the value has been entered, the following is displayed on the PC:

Second Calibration Point. Enter the Volts displayed: Adjust the 0 Percent of Scale, 8 for up 2 for down, Press Enter When Stable

The second part of the calibration adjustment follows. In the 10 key section of the PC keyboard, use the 8 (up arrow) to increase the output voltage displayed or 2 (down arrow) to decrease the output voltage displayed. Keep in mind the lag time between a change in output voltage to a stable display on the DMM. Make small changes then wait for a stable reading. Adjust the output so that you get a good, stable 0 V reading. When satisfied with the reading, press the Enter key.

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Calibration Adjustment

The PC display shows:

Please Wait… 25755

Adjust to 25 Percent of Scale, 8 for up 2 for down, Press Enter When Stable

The value is the raw A/D counts for this calibration point, followed by a prompt to adjust the 25 % of scale value. Use the 8 (up) and 2 (down) key on the PC to adjust the output to get a reading very close to 25 % of the range full scale.

• For the 100 mV range, 25 % is 25 mV

• For the 1 V range, 25 % is 250 mV

• For the 10 V range, 25 % is 2.5 V

• For the 100 V range, 25 % is 25 V

When satisfied with the reading, press Enter and the PC shows:

Please Wait… 2083980

525A

Adjust to 50 Percent of Scale, 8 for up 2 for down, Press Enter When Stable

The value is the raw A/D counts for this calibration point followed by a prompt to adjust the 50 % of scale value. Use the 8 (up) and 2 (down) key on the PC to adjust the output to get a reading very close to 50 % of the range full scale.

• For the 100 mV range, 50 % is 50 mV

• For the 1 V range, 50 % is 500 mV

• For the 10 V range, 50 % is 5.0 V

• For the 100 V range, 50 % is 50 V

This process continues until the user goes through the 100 % range. Use the same procedures for those ranges.

After the raw A/D counts are displayed, this calibration step is complete. The calibration constants for the range have been saved. Press Enter to return to the Calibration menu.

5: 100 mA Source, Adjusting DC Current Source

Adjusting the DC current output is similar to the voltage source calibration adjustment. Just like the voltage calibration adjustment, this adjustment is executed in 2 parts. Part 1 sets the 0 and span values. Part 2 is to fine adjust the zero, span, and adjusts the linearity. Refer to Table 18 for a list of equipment used in this section.

Table 18. List of Equipment for Current Calibration Adjustments

Manufacturer Model Equipment

Fluke FLUKE-525A/LEADS Test Lead Set Fluke 742A-10 Resistance Standard, 10 Ω Wavetek 1281 DMM

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Service Manual

The voltage is measured across a 10 Ω shunt resistor instead of measuring current directly.

Readings taken from the DMM need to be converted to mA (multiplied by 100) before they can be entered in at the PC.

1. Set the DMM to read DC Volts.

2. Use the test leads for the following connections: a. Connect the mA HI jack of the Calibrator to the high side of the current input of

the 742A.

b. Connect the mA LO jack of the calibrator to the low side of the current input of

the 742A.

c. Connect the high side of the sense output of the 742A to the high side of the

voltage input of the DMM.

d. Connect the low side of the sense output of the 742A to the low side of the

voltage into the DMM.

3. Type 5 and then press the Enter key on the PC. The following will be displayed on the PC:

First Calibration Point. Enter the mAmps displayed:

4. When the reading on the DMM stabilizes, calculate the mA (multiply the voltage reading by 100) and type the mA on the PC then press the Enter key. After the value has been entered, the following shows on the PC:

Second Calibration Point. Enter the mAmps displayed:

5. When the reading on the DMM stabilizes, calculate the mA (multiply the voltage reading by 100) and type the mA on the PC then press the Enter key. After the value has been entered, the following shows on the PC:

Second Calibration Point. Enter the volts displayed Adjust the 0 Percent of Scale, 8 for up 2 for down, Press Enter When Stable

The PC display shows:

Please Wait… 111260

Adjust to 25 Percent of Scale, 8 for up 2 for down, Press Enter When Stable

• For the 100 mA range, 25 % is 250 mV

When satisfied with the reading, press Enter and the PC shows:

Page 45

Please Wait… 2147203

Adjust to 50 Percent of Scale, 8 for up 2 for down, Press Enter When Stable

• For the 100 mA range, 50 % is 500 mV

Repeat this process until the user goes through the 100 % range. Use the same procedures for those ranges.

• For the 100 mA range, 75 % is 750 mV

• For the 100 mA range, 100 % is 1 V

After the raw A/D counts are displayed, this calibration step is complete. The calibration constants for the range have been saved. Press Enter to return to the Calibration menu.

6: Hi Ohms Source, Adjusting High Resistance Source

When calibrating the 5-4000 Ω output range (High Ohms Source), the calibrator outputs two calibration points. After the output becomes stable, the values are entered at the PC.

525A

Calibration Adjustment

1. Use the same test equipment listed in Table 16.

2. Make the following connections: a. Connect the HI RTD Ω jack of the Calibrator to the high side of the Ohms

measure sense jacks on the DMM.

b. Connect the LO RTD Ω jack of the Calibrator to the low side of the Ohms

measure sense jacks on the DMM.

c. Connect the HI RTD Ω jack of the Calibrator to the high side of the Ohms

measure current source jacks on the DMM.

d. Connect the LO RTD Ω jack of the Calibrator to the low side of the Ohms

measure current source jacks on the DMM. It is important that the sense leads be on the bottom of the stack on the Calibrator Ohms source jacks.

3. Set the DMM to measure 4-wire ohms.

4. Type 6, then the Enter key on the PC. The PC will display:

First Calibration Point. Enter the Ohms displayed:

5. When the reading dis pla yed on the DMM stabi lizes, type the reading value on the PC and press the Enter key. After the value has been entered, the PC displays the following:

Second Calibration Point. Enter the Ohms displayed:

6. When the reading dis pla yed on the DMM stabi lizes, type the reading value on the PC and press the Enter key. After the second value has been entered, the Calibrator will return to the calibration menu.

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Service Manual

7: Low Ohms, Adjusting Low Ohms Source

When calibrating the 5-400 Ω output range (High Ohms Source), the calibrator outputs two calibration points. After the output becomes stable, the values are entered at the PC.

1. Use the same test equipment listed in Table 16.

2. Use the same connections as in 6: Adjusting High Resistance Source.

3. Set the DMM to measure 4-wire ohms.

4. Type 7, then press the Enter key on the PC. The PC will display:

First Calibration Point. Enter the Ohms displayed:

5. When the reading dis pla yed on the DMM stabi lizes, type the reading value on the PC and press the Enter key. After the value has been entered, the PC displays the following:

Second Calibration Point. Enter the Ohms displayed:

8: Hi Ohms, Adjusting High Resistance Measure

When adjusting the calibration for the 5-4000 Ohms Measure range (High Ohms Measure), the Calibrator will first measure a short and then two resistances. Refer to Table 19 for a list of equipment used in this section.

Table 19. List of Equipment for High Ohms Measure Calibration Adjustments

Manufacturer Model Equipment

Fluke FLUKE-525A/LEADS Test Lead Set Fluke 742A-10K Resistance Standard, 10K Ω Fluke 5520A Calibrator Wavetek 1281 DMM

1. Insert a 4-wire short into the 525A 4W RTD Ω jacks.

2. Type 8 then press the Enter key on the PC. The following will show on the PC:

Input 0 Ohms, Press Enter When Stable

3. Allow a few seconds for stabilization, then press the Enter key. In a few moments the

following appears on the PC:

Input ~2000 Ohms, Enter the actual value when stable:

The ~2000 indicates that the desired resistance is about 2000 Ω. The actual resistance is not as important as the accuracy with which the value is known. The method described below uses the 1281 to establish a ratio between the 5520A output and the 742 to improve the accuracy with which the 5520A’s output resistance is known.

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1. Connect channel A of the 1281 to the resistance standard as follows: a. Connect I+ of the DMM to the high side of the current input of the resistance

standard.

b. Connect I- of the DMM to the low side of the current input of the resistance

standard.

c. Connect the high side (HI) of the DMM sense input to the high side of the sense

output of the resistance standard.

d. Connect the low side (LO) of the DMM sense input to the low side of the sense

output of the resistance standard.

2. Connect channel B of the 1281 to the 5520A as follows: a. Connect I+ of the DMM to the high side of the current input of the 5520A. b. Connect I- of the DMM to the low side of the current input of the 5520A. c. Connect the high side (HI) of the DMM sense input to the high side of the sense

output of the 5520A.

d. Connect the low side (LO) of the DMM sense input to the high side of the sense

output of the 5520A.

525A

Calibration Adjustment

3. Connect the 525A to the 5520A as follows: a. Connect the HI INPUT 4W RTD Ω jack of the Calibrator to the high side of the

current input of the 5520A.

b. Connect the LO INPUT 4W RTD Ω jack of the Calibrator to the low side of the

current input of the 5520A.

c. Connect the HI SENSE 4W RTD Ω jack of the Calibrator to high side of the

sense output of the 5520A.

d. Connect the LO SENSE 4W RTD Ω jack of the Calibrator to the low side of the

sense output of the 5520A.

4. Set the 5520A to source 2000 Ω.

5. Using the 2 channels on the DMM, calculate the actual value of the 5520A’s output. This is done by using the ratio of a known standard to the output of the 5520A. The 1281 can be used to calculate the ratio or proceed as follows:

Ratio = A/B RA = RS/Ratio

Where: A = The reading from channel A of the DMM B = The reading from channel B on the DMM RS = The value of the resistance standard (in this case 10K) RA = The actual output of the 5520A

After the actual output value, the PC displays the following:

Input ~4000 Ohms, Enter the actual value when stable

1. Set the 5520A to source 4000 Ω (nominal) and enter the actual value calculated

as described above.

After the value is entered, the calibration constants will be saved and the display returns to the main Calibration Menu.

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Service Manual

9: Low Ohms, Adjusting Low Resistance Measure

When adjusting the calibration for the 5-400 Ohms Measure range (Low Ohms Measure), the Calibrator will measure 3 resistances. Refer to Table 20 for a list of equipment used in this section.

Table 20. List of Equipment for High Ohms Measure Calibration Adjustments

Manufacturer Model Equipment

Fluke FLUKE-525A/LEADS Test Lead Set Fluke 742A-100 Resistance Standard, 100 Ω Fluke 5520A Calibrator Wavetek 1281 DMM

The method described below uses the 1281 to establish a ratio between the 5520A output and the 742 to improve the accuracy with which the 5520A’s output resistance is known.

1. Connect channel A of the 1281 to the Resistance Standard as follows: a. Connect I+ of the DMM to the high side of the current input of the Resistance

Standard.

b. Connect I- of the DMM to the low side of the current input of the Resistance

Standard.

c. Connect the high side (HI) of the DMM sense input to the high side of the sense

output of the resistance standard.

d. Connect the low side (LO) of the DMM sense input to the low side of the sense

output of the resistance standard.

output of the 5520A.

d. Connect the low side (LO) of the DMM sense input to the low side of the sense

output of the 5520A.

3. Connect 525A to the 5520A as follows: a. Connect HI INPUT 4W RTD Ω jack of the 525A to the high side of the current

input of the 5520A.

b. Connect LO INPUT 4W RTD Ω jack of the 525A to the low side of the current

input of the 5520A.

c. Connect the HI SENSE 4W RTD Ω jack of the 525A to the high side of the sense

output of the 5520A.

d. Connect the LO SENSE 4W RTD Ω jack of the 525A sense input to the low side

of the sense output of the 5520A.

4. Type 9 {enter} on the PC. The following will be displayed on the PC.

Input ~100 Ohms, Enter the actual value when stable:

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Calibration Adjustment

The ~100 indicates that the desired resistance is about 100 Ω. The actual resistance is not as important as the accuracy with which the value is known.

5. Set the 5520A to source 100 Ω.

6. Using the two channels on the DMM, calculate the actual value of the 5520A’s output. This is done by using the ratio of a known standard to the output of the 5520A. You can use the 1281 to calculate the ratio or proceed as follows.

Ratio = A/B RA = RS/Ratio Where: A = The reading taken from channel A on the DMM. B = The reading taken from channel B on the DMM. RS = The value of the resistance standard (in this case 100 Ω). RA = The actual output of the 5520A.

After the actual output value is entered, the PC displays the following:

Input ~200 Ohms, Enter the actual value when stable:

525A

7. Set the 5520A to source 200 Ω (nominal) and enter the actual value calculated as described above.

Set Input ~400 Ohms, Enter the actual value when stable:

8. Set the 5520A to source 400 Ω (nominal) and enter the actual value calculated as described above.

After the value is entered, the calibration constants will be saved and the display will return to the main Calibration Menu.

10: SPRT 25, Adjusting SPRT Low Resistance Measure

The SPRT 25 range is used for measuring SPRTs (typically 25 Ohm R0) and Ohms from 0 to 100 Ohms in the 0-400 Ohms range. The 525A will measure a short, and 2 resistances. Refer to Table 21 for a list of equipment used in this section.

Table 21. List of Equipment for Low Ohms Measure Calibration Adjustments

Manufacturer Model Equipment

Fluke FLUKE-525A/LEADS Test lead set Fluke 742A-100 Resistance Standard, 100 Ω Fluke 5520A Calibrator Wavetek 1281 DMM

1. Insert a good 4-wire short into the 525A 4W RTD Ω jacks.

2. Type 10 and press the Enter key on the PC. The following is displayed on the PC.

Input 0 Ohms, Press Enter When Stable

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3. Allow a few seconds for everything to stabilize, then press the Enter key. In a few moments the following is displayed on the PC:

Input ~50 Ohms, Enter the actual value when stable:

The ~50 indicates that the desired resistance is about 50 Ω. The actual resistance is not as important as the accuracy with which the value is known. The method described below uses the 1281 to establish a ratio between the 5520A output and the 742 to improve the accuracy with which 5520As output resistance is known.

4. Connect channel A of the 1281 to the Resistance Standard as follows:

1. Connect I+ of the DMM to the high side of the current input of the Resistance

Standard.

2. Connect I- of the DMM to the low side of the current input of the Resistance

Standard.

3. Connect the high side (HI) of the DMM sense input to the high side of the sense

output of the resistance standard.

4. Connect the low side (LO) of the DMM sense input to the low side of the sense

output of the resistance standard.

5. Connect channel B of the 1281 to the 5520A as follows: a. Connect I+ of the DMM to the high side of the current input of the 5520A. b. Connect I- of the DMM to the low side of the current input of the 5520A. c. Connect the high side (HI) of the DMM sense input to the high side of the sense

output of the 5520A.

d. Connect the low side (LO) of the DMM sense input to the low side of the sense

output of the 5520A.

6. Connect 525A to the 5520A as follows: a. Connect HI INPUT 4W RTD Ω jack of the 525A to the high side of the current

input of the 5520A.

b. Connect LO INPUT 4W RTD Ω jack of the 525A to the low side of the current

input of the 5520A.

c. Connect the HI SENSE 4W RTD Ω jack of the 525A to the high side of the sense

output of the 5520A.

d. Connect the LO SENSE 4W RTD Ω jack of the 525A sense input to the low side

of the sense output of the 5520A.

7. Set the 5520A to source 50 Ω.

8. Using the two channels on the DMM, calculate the actual value of the 5520A’s output. This is done by using the ratio of a known standard to the output of the 5520A. The 1281 can be used to calculate the ratio or proceed as follows.

Ratio = A/B RA = RS/Ratio Where: A = The reading taken from channel A on the DMM. B = The reading taken from channel B on the DMM. RS = The value of the resistance standard (in this case 10K).

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RA = The actual output of the 5520A.

9. After the actual output value is entered, the PC displays the following:

Input ~100 Ohms, Enter the actual value when stable:

10. Set the 5520A to source 100 Ω (nominal) and enter the actual value calculated as described above.

After entering the value, the calibration constants will be saved and the display returns to the main Calibration Menu.

11: TC SOURCE, Adjusting TC mVolt Source

The adjust of the TC Source output range is similar to the first part of the voltage source calibration, the 525A outputs two Adjust points, after the output becomes stable the values can be entered at the PC. Refer to Table 22 for a list of equipment used in this section.

Table 22. List of Test Equipment for Adjusting TC Source

Manufacturer Model Equipment

525A

Calibration Adjustment

Fluke FLUKE-525A/LEADS Test lead set Wavetek 1281 DMM

1. Use a copper TC mini-plug cable with low thermal EMF jacks on the other end to connect the Calibrator to the DMM. Make certain the polarity is correct. Set the DMM to read DC Volts.

2. Type 11 and press the Enter key on the PC. The following is displayed on the PC:

First Calibration Point. Enter the Volts displayed:

3. When the reading dis pla yed on the DMM stabi lizes, type the reading value on the PC and press the Enter key. After the value has been entered, the following is displayed on the PC.

Second Calibration Point. Enter the Volts displayed:

4. When the reading dis pla yed on the DMM stabi lizes, type the reading value on the PC and press the Enter key.

After the calibration constants are saved, the Calibration Menu is displayed on the PC.

12: TC Read, Adjusting TC mVolt Measure

The adjust of the TC Source output range is similar to the first part of the voltage source calibration, the Calibrator outputs 2 adjustment points, after the output stabilizes, the values can be entered from PC. Refer to Table 23 for a list of equipment used in this section.

Table 23. List of Test Equipment for Adjusting TC Read

Manufacturer Model Equipment

Fluke FLUKE-525A/LEADS Test lead set Wavetek 1281 DMM

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Service Manual

Use a copper TC mini-plug cable with low thermal EMF jacks on the other end to connect the 525A to the DMM. Make certain the polarity is correct.

1. Set the DMM to read DC Volts.

2. Type 12 and press the Enter key on the PC. The following is displayed on the PC:

Adjust to -10 mV, 8 for up 2 for down, Press Enter When Stable

3. In the 10 key section of the PC keyboard, use the 8 (up arrow) to increase the output voltage displayed or 2 (down arrow) to decrease the output voltage displayed. Keep in mind the lag time between a change in output voltage to a stable display on the DMM and make small changes. Wait for the reading to stabilize.

4. Adjust the output so that there is a stable -10 mV reading. When satisfied with the reading, press the Enter key on the PC. The PC display will show:

Please Wait...

-1073806

Adjust to 15 mV, 8 for up 2 for down, Press Enter When Stable

5. The value is the raw A/D counts for this calibration point, followed by a prompt to adjust for 15 mV. Use the 8 (up) and 2 (down) key on the PC to adjust the output so that a reading very close to 15 mV is obtained.

6. When satisfied with the reading, press the Enter key. The PC display shows:

Please Wait... 1610975

Adjust to 40 mV, 8 for up 2 for down, Press Enter When Stable

7. The value is the raw A/D counts for this calibration point, followed by a prompt to adjust for 40 mV. Use the 8 (up) and 2 (down) key on the PC to adjust the output so that a reading very close to 40 mV is obtained.

8. When satisfied with the reading, press the Enter key. The PC display shows:

Please Wait... 4295762

Adjust to 65 mV, 8 for up 2 for down, Press Enter When Stable

9. The value is the raw A/D counts for this calibration point, followed by a prompt to adjust for 65 mV. Use the 8 (up) and 2 (down) key on the PC to adjust the output so that a reading very close to 65 mV is obtained.

10. When satisfied with the reading, press {enter}. The PC display will show:

Please Wait... 6980475

Adjust to 75 mV, 8 for up 2 for down, Press Enter When Stable

11. The value is the raw A/D counts for this calibration point, followed by a prompt to adjust for 75 mV. Use the 8 (up) and 2 (down) key on the PC to adjust the output so

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Customer Replaceable Parts

that a reading very close to 75 mV is obtained. When satisfied with the reading, press the Enter key. The PC display will show:

Please Wait... 8054372

12. After the raw A/D counts are displayed, the calibration step is complete. The calibration constants for the range have been saved. Press the Enter key to return to the Calibration Menu.

13: TC CJC, Adjusting TC Cold Junction Temperature

The Calibration of the TC CJC (cold junction compensation) is a critical part of the calibration adjustment process. It is important that the thermocouple junction be allowed to completely stabilize. Refer to Table 24 for a list of equipment used in this section.

Table 24. List of Test Equipment for Adjusting TC CJC

Manufacturer Model Equipment

Hart Scientific 1521 Precision Thermometer Omega J Thermocouple Probe

525A

_ _ Lag Bath __RTD Probe

The precision thermometer’s probe should already be in the lag bath along with the J thermocouple probe.

1. Plug the mini-plug on the J thermocouple probe into the TC jack on the Calibrator.

2. Type 12 and press the Enter key on the PC. The following is displayed on the PC:

Input a Type J Thermocouple. Enter temperature when stable.

3. Allow about three minutes for all of the thermal junctions to stabilize.

4. Enter the temperature from the temperature reference. The final display should look like the following.

Input a Type J Thermocouple. Enter temperature when stable. 377376 26.699269

1103.936911

1124.668121

0.000000

-20.731080

26.698029

5. Press the Enter key to return to the Calibration Menu.

Customer Replaceable Parts

Replacement parts are shown in Figure 14. Table 25 provides a description and part number of each replacement part. Table 26 lists optional accessories.

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Service Manual

Figure 14. Exploded View of the 525A

ajr20f.eps

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Customer Replaceable Parts

Table 25. Replacement Parts

Part

Item #

1 1601576 525A Front Panel Decal Front Of Top Chassis 1 2 1617918 Fuse Drawer Power Module 1

W3 1645311 Fuse, (1/4A), FB For 1x0 VAC Fuse Drawer 2 W4 1645327 Fuse, (1/8A), FB For 2x0 VAC Fuse Drawer 2

5 1601601 525A Output Block Front Plate 1 6 295105 Allen Head Screw Handles To Case 20 7 320093 Flathead Screw Top Cover 10 8 1601583 525A Chassis Base 1 9 1601590 525A Instrument Top Cover 1 10 886341 Chassis Handles Front/Rear Chassis 4 11 868786 Plastic Feet Bottom of Chassis 4

Number Description Location Quantity

525A

12 1601078 Programming Door Back of Chassis Base 1 13 886382 Red 5-Way Binding Post Output Block 5 14 886379 Black 5-Way Binding Post Output Block 5 15 859939 #8 Washer, Low Thermal Output Block 10 16 850334 8-32 Nut, Low Thermal Output Block 10 17 942714 Pressure Conn, Circ, 5 Socket Output Block 1 18 1601565 525A Keypad Front Of Top Chassis 1 20 1618591 Main PCA 1 20* 1642173 PEP Main PCA 1 22 1617941 Display PCA 1 23 1618617 Keypad PCA 1 24 1640190 6-32 X 3/8" Screw, Nylon, Pan, Display To Chassis 4 25 1640305 Nylock Nut 6-32 Block To Chassis 5 25 1640305 Nylock Nut 6-32 Power Module to Chassis 2 26 494641 5-20 X .312, Screw TC PCA To Output Block 2 27 110338 #6, Int Tooth Lock Washer Main PCA To Chassis 6 27 152181 6-32 X 5/8’’ Screw, Round Main PCA To Chassis 6 28 1640225 6-32 X 2-1/2" Screw, Ph Transformer To Chassis 4 29 1640202 #6 Nylon Washer Display PCA To Chassis 4 29 1640202 #6 Nylon Washer Transformer 4 30 1618600 TC PCA 1

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Service Manual

Table 25. Replacement Parts (continued)

Part

Item #

31 1617929 Power Module Back Of Chassis 1 32 1617907 Voltage Selector Power Module 1 33 1638939 Opto RS232 PCA Back of Chassis 1 Not shown 271973 .1uf/250V Cap., Polyester Output Block 1 Not shown 1617866 14 Cond Ribbon Cable J4 To Display 1 Not shown 1617882 5 Cond Ribbon Cable Lemo PCA To Main PCA 1 Not shown 1627364 12 Cond Ribbon Cable J11 To Keypad PCA 1 34 1640331 Pressure-Lemo PCB Lemo Connector 1 Not shown 172080 Cable Tie, 4’’ 4 Not shown 1618621 Line Cord, 3 COND 1 Not shown 110338 #6, Int Tooth Lock Washer Keypad PCA to Chassis 5

Number Description Location Quantity

Not shown 152165 #6 X 3/8" Screw, PH Keypad PCA to Chassis 5 Not shown 152165 #6 X 3/8" Screw, PH Power Module to Chassis 2 Not shown 152165 #6 X 3/8" Screw, PH Program Door to Chassis 1 Not shown 721266 Lug, Closed, Round, #8 Stud Output Block 11 Not shown 110619 1/4"-28 Nut Ground Lug Stud 2 Not shown 448092 Jack Screw RS232 Conn 9 Pin D-Sub 1 Not shown 110338 1/4" Int Tooth Lock Washer Binding Post Stud 2 Not shown 102889 Binding Head Thumbscrew Binding Post Stud 1 Not shown 102707 Binding Post Jack Chassis Back 1 Not shown 1601541 525A Getting Started Guide 1 Not shown 1601552 525A User Manual (on CD) 1 W For safety, use exact replacement only. * PEP is an exchange of a repairable assembly for a factory repaired one.

Table 26. Accessories

Description Part Number

Fluke 525A/LEAD, Lead wire set 1616018

Fluke Y525 Rack Mount Kit 1622027 RS43, RS232 Null Modem Cable 946470 525A Service Manual 1644492

Fluke 525A Service Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Service Manual

LIMITED WARRANTY AND LIMITATION OF LIABILITY

Table of Contents

List of Tables

List of Figures

Introduction

Contacting Fluke

Safety Information

Calibrator Specifications

General Specifications

DC Voltage Specifications, Output

DC Current Specifications, Output

Resistance Specifications, Output

Resistance Specifications, Input

Thermocouple Specification, Output and Input

TC mV Specifications, Input and Output

RTD and Thermistor Specification, Output

RTD and Thermistor Specification, Input

Pressure Measurement

Theory of Operation

Micro-Controller Section

Analog Section

Basic Maintenance

Cleaning the Calibrator

Replacing a Line Fuse

To Check or Replace a Fuse

Changing Line Voltage

Modular-Level Maintenance

Disassembly

Reassembly

Output Block Subassembly Connections

Keypad PCA to Main PCA

Display Assembly to Main PCA

Opto RS232 PCA to Main PCA

Reinstalling the Circuit Boards

Connecting the Power Module

Final Assembly and Inspection

Performance Tests

Required Equipment List

Testing DC Voltage

Testing DC Current

Testing Thermocouple Output

Testing CJC (Cold Junction Compensation)

CJC (Cold Junction Compensation) Calibration

Testing Thermocouple Input

Testing Ohms Output

Testing Ohms Input

Testing Pressure Modules

Calibration Adjustment

Initiating Communication

Starting Adjustment Mode

Adjustment Sequence

14: Calibrate DAC, Digital to Analog Converter Adjustment

1: 100 mV Source to 4: 100 V Source, Adjusting DC Source

5: 100 mA Source, Adjusting DC Current Source

Customer Replaceable Parts