Oki OKIOFFICE84 Maintenance Manual page 470

2: Operation not responded
Clock display normal
Yes
LED is not lit.
No
Key are not responded
No
See 1: LCD is not displayed.
No
Yes
A pin either pin 33
through pin 48 of IC1 changes
to 5V or near 0V when the
LED should be lit
Replace IC1.
Yes
An input ports pins 4
through 11 of IC1 change
when the key is pressed
Replace IC1.
H - 15
See 1: LCD is not displayed.
Yes
No
Replace LED.
No
Yes
Replace the switch.
40672201TH Rev. 4