Keithley 2400 Service Manual

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.
Digital +5V supply.
Display +37V 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.

Keithley 2400 Specifications

General

Brand	Keithley
Model	2400
Category	Measuring Instruments
Language	English