
Table of Contents
1. INTRODUCTION ....................................................................................................................................1
2. SPECIFICATIONS...................................................................................................................................3
3. DESCRIPTION OF CONTROLS AND FUNCTIONS ...........................................................................5
FRONT PANEL...........................................................................................................................................5
REAR PANEL .............................................................................................................................................6
INTERNAL CONTROLS ...............................................................................................................................6
4. SAFETY CONSIDERATIONS AND MAINTENANCE........................................................................9
ENVIRONTMENTAL CONDITIONS FOR NORMAL USE .................................................................................9
CLEANING INSTRUCTIONS AND PRECAUTIONS ..........................................................................................9
REPLACEMENT OF FUSES .........................................................................................................................10
MAINTENANCE.........................................................................................................................................10
INSTRUMENT RETURN FOR REPAIR/CALIBRATION ..................................................................................10
BATTERY REPLACEMENT.........................................................................................................................11
ELECTRICAL SAFETY PRECAUTIONS........................................................................................................11
5. OPERATING PROCEDURES...............................................................................................................12
THEORY OF OPERATION ...........................................................................................................................13
DETECTOR INPUT/AMPLIFIER ........................................................................................................13
ALPHA/BETA DISCRIMINATOR......................................................................................................13
ALPHA/BETA DISCRIMINATOR LOGIC CIRCUIT .............................................................................14
LOW VOLTAGE SUPPLY .................................................................................................................14
HIGH VOLTAGE SUPPLY.................................................................................................................14
DETECTOR OVERLOAD...................................................................................................................14
METER DRIVE.................................................................................................................................15
MICROPROCESSOR..........................................................................................................................15
AUDIO .............................................................................................................................................15
6. RECYCLING..........................................................................................................................................16
7. PARTS LIST...........................................................................................................................................17
MAIN BOARD (DRAWING 347 X 600).......................................................................................................17
FRONT PANEL BOARD (DRAWING 347 X 244) .........................................................................................20
CHASSIS WIRING DIAGRAM (DRAWING 347 X 243).................................................................................21
8. APPENDIX.............................................................................................................................................22
APPENDIX 1–CHECKOUT PROCEDURE....................................................................................................22
APPENDIX 2–MODEL 177-84 MODE SWITCH ADDITION........................................................................24
APPENDIX 3–MODEL 4902 SPECIFICATIONS ..........................................................................................25
9. DRAWINGS AND DIAGRAMS...........................................................................................................26