
Service Information
4-10
Table 4-3
Troubleshooting procedure
Step
Item/component
Required
condition
Comments
1
2
3
4
5
6
Digital ground P1034, pin 1, 3, 5
P1034, pin 9
U102, pin 2
U102, pin 3
U102, pin 7
U102-U104, pins 10-18
+5VDC
CLK pulses
DATA pulses
STR pulse
Low with relay
All voltages referenced to digital ground.
Card power supply voltage.
During relay update sequence only.
During relay update sequence only.
End of relay update sequence.
Relay driver outputs. Low with relay energized,
high with relay de-energized.
Summary of Contents for 6521
Page 12: ...iv...
Page 14: ...vi...
Page 16: ...viii...
Page 20: ...General Information 1 4...
Page 28: ...Card Connections and Installation 2 8...
Page 42: ...Operation 3 14...
Page 56: ...Replaceable Parts 5 4...
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