TABLE OF CONTENTS
MODELS 868 AND 869 DIGITAL THERMOMETERS
SECTION
PAGE
SECTION 1 INTRODUCTION ....................................................1
1.1
General Description....................................................................................................................1
1.2
Features ................................................................................................................................................1
SECTION 2 INSTALLATION......................................................1
2.1
Unpacking ..........................................................................................................................................1
2.2
Battery Installation......................................................................................................................2
SECTION 3 OPERATION ........................................................2
3.1
Safety Precaution and Notes..............................................................................................2
3.2
Control and Display ..................................................................................................................2
3.3
Operating Procedure................................................................................................................3
3.4
Accuracy Considerations ....................................................................................................4
3.5
Three Wire and Four Wire Operations......................................................................4
SECTION 4 THEORY OF OPERATION......................................6
4.1
Three Wire Signal Conditioning ......................................................................................6
4.1.1
Zero Phase........................................................................................................................................6
4.1.2
Signal Phase ....................................................................................................................................7
4.2
Four Wire Signal Conditioning..........................................................................................9
4.2.1
Zero Phase........................................................................................................................................9
4.2.2
Signal Phase ..................................................................................................................................10
4.3
Analog-to-Digital (A/D) Converter ..............................................................................11
4.4
Polarity Detector..........................................................................................................................11
4.5
FET Drivers ........................................................................................................................................11
4.6
Low-Battery Detector ............................................................................................................12
SECTION 5 SERVICE INFORMATION......................................12
5.1
Disassembly ..................................................................................................................................12
5.2
Calibration ....................................................................................................................................14
5.3
Probe Compensation ..............................................................................................................16
5.4
Troubleshooting..........................................................................................................................16
5.4.1
Voltage Checks ..........................................................................................................................17
5.4.2
A/D Converter Checks ........................................................................................................17
5.4.3
Waveform Checks....................................................................................................................18
5.5
Static Sensitive Parts ..............................................................................................................19
5.6
Performance Verification ....................................................................................................19
SECTION 6 SPECIFICATIONS ................................................21
6.1
Parts List for Models 868 and 869..............................................................................24
Summary of Contents for 868F
Page 1: ......
Page 4: ...jumper ...
Page 7: ...figure 3 2 jumper ...
Page 11: ......
Page 14: ......
Page 17: ...jumper ...
Page 23: ...jumper jumper ...
Page 28: ...Jumper strip ...
Page 29: ...26 ...
Page 30: ...27 ...
Page 31: ...28 ...
Page 32: ...29 ...
Page 33: ...NOTES 30 ...
Page 34: ...31 NOTES ...
Page 36: ...0315 ...