Oki OKIFAX4550 Maintenance Manual page 546

4.1.12 Operation interface not operating correctly
12: Operation interface
does not operate correctly
Pin 77 of IC2 remains
at 0V
No
Pin 79 of IC2 remains at
0V or 5V
No
Pin 1 of CN4 changes to
0V or 5V when the operation
panel key is pressed
Yes
Pin 2 of CN4 changes to
0V or 5V when the operation
panel keys are pressed
No
Check CN4 connection.
41309401TH Rev.4
Yes
Yes
Pin 5 of IC15 remains at
0V or 5V
Replace IC15.
No
Inputs of pins 11 and 9
of IC15 change to 0V or 5V
when the operation panel
key is pressed
Replace IC15.
Yes
Output waveforms of pins
2 and 4 of IC15 change to
0V or 5V when the operation
panel key is pressed
Replace IC15.
Yes
No
Check CN4
connection.
No
Yes
Yes
No
Replace IC2.
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