4.2 Troubleshooting plan - Probable defective control circuit
1. No input can be
programmed.
Continuity.
No continuity.
Defective PCB
assembly.
Replace PCB
assembly.
Check the conn-
ection between
membrane key
assembly and
PCB assembly.
Loose
connection.
Connect them
tightly.
2. Some inputs
cannot be
programmed.
Everything works
as specified.
Still have trouble.
Defective key
membrane
assembly.
Replace key
membrane
assembly.
Replace key
membrane
assembly and
check operation.
3. Display shows a
number or figure
different from one
touched.
4. Random
programming
when touching
other pads.
5. Display is fixed
at some figure
and can not
accept any
input.
Defective PCB
assembly.
Replace PCB
assembly.
CONDITION
CHECK
RESULT
CAUSE
REMEDY
The following visual conditions indicate a probable defective control circuit.
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