Oki OKIOFFICE84 Maintenance Manual page 464

8: Receiving NG
RING signal cannot be
detected
No
Protocol signal receiving is NG
No
Signals cannot be sent.
During protocol signal sending,
sine wave or modulated sine wave
output is provided between pin
1 and pin 2 of IC8
Yes
During protocol signal sending,
sine wave or modulated sine wave
output is provided at pin 7 of IC12
Yes
Check CN10.
Yes
5V and 0V are alternately
input to pin 9 of IC14,
synchronized with the
RING signal
No
Check CN10.
Yes
During protocol signal receiving,
sine wave or modulated sine wave
input is provided between pins
2 and 3 of IC12
Yes
During protocol signal receiving,
sine wave or modulated sine wave
output is provided between pins
60 and 61 of IC8
Yes
No
Replace IC8.
No
H - 9
Yes
Pin 2 of IC2 repeats 5V and
No
0V cyclically, synchronized
with the RING signal
Replace IC14.
No
Check CN10.
No
Replace IC12.
Yes
Replace IC1.
40672201TH Rev. 4