Oki OKIFAX4550 Maintenance Manual page 558

4.2.12 Operation interface not operating correctly
12: Operation interface
does not operate correctly
Pin 101 of CPU1
remains at 0V
No
Pin 92 of CPU1
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 9 of IC15 remains at
0V or 5V
Replace IC15.
No
Inputs of pins 13 and 3
of IC15 change to 0V or
5V when the operation
panel key is pressed
Replace IC15.
Yes
Output waveforms of pins
11 and 5 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 CPU1.
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