Oki OKIOFFICE84 Maintenance Manual page 460

4: Heater NG
(printer alarm 4)
Pin 27 of IC2 repeated
5V and 0V ON/OFF
during printing
Yes
Pin 1 results in 5V
output when approximately
3V is input to pin 3 of IC18
Yes
Pin 3 becomes lower than
1V when 5V is input to pin 2
of TR504
Yes
The value of voltage input
to pin 47 of IC2 is normal?
Printing: 2V to 3.5V
Standby mode: Lower
than 0.5V
(when pin 2 of TR506 is at 5V)
Yes
Pin 3 is lower than 2V
when 5V is input to pin 2
of TR506
Yes
Check CN7.
No
No
No
No
No
H - 5
Replace IC2.
Replace IC18.
Replace TR504.
Replace IC2.
Replace TR506.
40672201TH Rev. 4