Keithley 2500, Service Manual

Page: 9 / 121

3 Routine Maintenance
Introduction ................................................................................ 3-2
Line voltage selection ................................................................. 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 ................................................. 4-3
CHAR SET test ................................................................... 4-4
Principles of operation ................................................................ 4-4
Overall block diagram ......................................................... 4-5
Analog circuits .................................................................... 4-6
Power supply ....................................................................... 4-8
Digital circuitry ................................................................... 4-9
Troubleshooting ........................................................................ 4-10
Display board checks ........................................................ 4-10
Power supply checks ......................................................... 4-11
Digital circuitry checks ..................................................... 4-12
Analog circuitry checks ..................................................... 4-13
No comm link error .................................................................. 4-14
5 Disassembly
Introduction ................................................................................ 5-2
Handling and cleaning ................................................................ 5-2
Handling PC boards ............................................................ 5-2
Solder repairs ....................................................................... 5-2
Static sensitive devices ............................................................... 5-3
Assembly drawings ..................................................................... 5-3
Case cover removal ..................................................................... 5-4
Input board removal .................................................................... 5-4
Mother board removal ................................................................ 5-5
Front panel disassembly ............................................................. 5-6
Removing power components .................................................... 5-6
Power supply module removal ............................................ 5-6
Power module removal ........................................................ 5-6
Power transformer removal ................................................. 5-7