Troubleshooting Procedure - Keithley 7021 Instruction Manual

Service Information

Troubleshooting procedure

Table 6-6 summarizes multiplexer-digital I/O card trouble-
shooting.
Table 6-6
Troubleshooting procedure
Step Item/component
1 GND pad
2 Q100, pin 2
3 U101, pin 16
4 R135
5 Q100, pin 3
6 U110, pin 6
7 U110, pin 5
8 U106, pin 7
9 U106, pin 2
10 U106, pin 3
11 U105-U109, pins 10-18
*+3.5VDC present at +V pad under steady-state conditions. This voltage rises to +5.7VDC for about 100msec when relay configuration is changed.
6-18
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Required condition
+6VDC
+5VDC
+15VDC
+3.5VDC*
IDCLK pulses
IDDATA pulses
STROBE pulse
CLK pulses
DATA pulses
Low with relay energized; high
with relay de-energized.
Comments
All voltages referenced to digital ground
(GND pad).
Relay voltage.
Logic voltage.
Relay bias voltage.
Regulated relay voltage.
During power-up only.
During power-up only.
End of relay update sequence.
During relay update sequence only.
During relay update sequence only.
Relay driver outputs.