Keithley SourceMeter 3A 2420, Service Manual

Page: 9 / 136

Changing the password ....................................................................... 2-6
Changing the password from the front panel ............................... 2-6
Changing the password by remote ............................................... 2-6
Resetting the calibration password...................................................... 2-6
Viewing calibration dates and calibration count ................................. 2-7
Calibration errors ............................................................................. 2-7
Front panel error reporting ........................................................... 2-7
Remote error reporting ................................................................. 2-7
Front panel calibration ........................................................................ 2-7
Remote calibration ............................................................................ 2-14
Remote calibration commands ................................................... 2-14
Recommended calibration parameters ....................................... 2-15
Remote calibration procedure .................................................... 2-17
Single-range calibration .................................................................... 2-22
3
Routine Maintenance
Introduction ......................................................................................... 3-2
Line fuse replacement ......................................................................... 3-2
4
Troubleshooting
Introduction ......................................................................................... 4-2
Repair considerations .......................................................................... 4-2
Power-on self-test................................................................................ 4-2
Front panel tests .................................................................................. 4-3
KEYS test..................................................................................... 4-3
DISPLAY PATTERNS test .......................................................... 4-3
CHAR SET test ............................................................................ 4-4
Principles of operation ........................................................................ 4-4
Overall block diagram .................................................................. 4-4
Analog circuits ............................................................................. 4-4
Power supply ................................................................................ 4-6
Output stage.................................................................................. 4-7
A/D converter ............................................................................... 4-8
Active guard ................................................................................. 4-8
Digital circuitry ............................................................................ 4-8
Display board circuit theory......................................................... 4-9
Troubleshooting ................................................................................ 4-10
Display board checks ................................................................. 4-10
Power supply checks .................................................................. 4-11
Digital circuitry checks .............................................................. 4-11
Analog circuitry checks.............................................................. 4-12
Battery replacement .......................................................................... 4-12
Battery replacement precautions ................................................ 4-12
Battery replacement procedure................................................... 4-13
No comm link error ........................................................................... 4-13