Keithley SourceMeter 2400, Service Manual, Page: 64 / 137

2400-902-01 (G - Feb 2006)
Model 2400 Service Manual 4-10
Troubleshooting
Troubleshooting
Troubleshooting information for the various circuits is summarized in the following
paragraphs.
Display board checks
If the front panel display tests indicate that there is a problem on the display board, use
Table 4-1. See “Principles of operation” for display circuit theory.
Table 4-1
Display board checks
Step Item/component Required condition Remarks
1
2
3
4
5
6
7 Front panel test
P1005, pin 5
P1005, pin 9
U902, pin 1
U902, pin 43
U902, pin 32
U902, pin 33 Verify that all segments operate.
+5V ±5%
+37V ±5%
Goes low briefly on power up, and then goes high.
4MHz square wave.
Pulse train every 1 ms.
Brief pulse train when front panel key is pressed. Use front panel display test.
D5V supply.
D37V supply.
Microcontroller RESET.
Controller 4MHz clock.
Control from main processor.
Key down data sent to main
processor.
Power supply checks
Power supply problems can be checked using Table 4-2. See “Principles of operation” for cir-
cuit theory on the power supply. Note that the power supply circuits are located on the digital
board.
Table 4-2
Power supply checks
Step Item/component Required condition Remarks
1
2
3
4
5
6
7 Line fuse
Line power
TP5
TP6
TP7
TP8
TP9 Check continuity.
Plugged into live receptacle, power on.
+5V ±5%
+15V ±5%
-15V ±5%
~-35V
~+35V Remove to check.
Check for correct power-up sequence.
+5VF, referenced to Common F3
1
.
+15VF, referenced to Common F2
2
.
-15VF, referenced to Common F2.
-30VF, referenced to Common F2.
+30VF, referenced to Common F2.
1
U18, pin 2.
2
U8, pin 1.