Keithley SourceMeter 2425, Service Manual

Page: 9 / 141

Unlocking calibration ................................................................. 2-5
Unlocking calibration from the front panel ......................... 2-5
Unlocking calibration by remote ......................................... 2-6
Changing the password ............................................................... 2-7
Changing the password from the front panel ...................... 2-7
Changing the password by remote ...................................... 2-7
Resetting the calibration password ............................................. 2-8
Viewing calibration dates and calibration count ........................ 2-8
Calibration errors ........................................................................ 2-8
Front panel error reporting .................................................. 2-8
Remote error reporting ........................................................ 2-9
Front panel calibration ................................................................ 2-9
Remote calibration .................................................................... 2-18
Remote calibration commands .......................................... 2-18
Recommended calibration parameters .............................. 2-19
Remote calibration procedure ........................................... 2-20
Single-range calibration ............................................................ 2-26
3 Routine Maintenance
Introduction ................................................................................ 3-2
Line fuse replacement ................................................................. 3-2
4 Troubleshooting
Introduction ................................................................................ 4-2
Safety considerations .................................................................. 4-2
Repair considerations ................................................................. 4-2
Power-on self-test ....................................................................... 4-3
Front panel tests .......................................................................... 4-3
KEYS test ............................................................................ 4-3
DISPLAY PATTERNS test ................................................ 4-4
CHAR SET test ................................................................... 4-4
Principles of operation ................................................................ 4-5
Overall block diagram ......................................................... 4-5
Analog circuits .................................................................... 4-7
Power supply ....................................................................... 4-8
Output stage ......................................................................... 4-9
A/D converter .................................................................... 4-11
Active guard ...................................................................... 4-11
Digital circuitry ................................................................. 4-11
Display board circuit theory .............................................. 4-12