Fluke 525A Temperature/Pressure Calibrator Service Manual

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
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

56 pages