Ricoh FT4480 Field Service Manual page 222

LIGHT COPY
- P o s s i b l e C a u s e s -
Development bias not applied or defective bias power pack
Defective main board
Defective dc power supply
- Action -
Does the image density change with ID selection?
Y N
I
Is the development bias applied?
Y N
I
Does the bias power pack receive the proper trigger signal from
the main board?
Y N
I
Replace the main board.
Check for electrical continuity between the bias terminal and
the development sleeve. Correct any poor contact or faulty
wiring. If that isn't effective, replace the bias power pack.
Does the toner supply clutch work properly?
Y N
I
Does CN230-4 drop from +24 volts to ground?
Y N
I
Does CN202-A7 go from +24 volts to ground?
Y N
I
Replace the main board.
Replace the paper feed relay board.
Clean or replace the toner supply clutch.
Other possible causes:
1. Charge corona
2. Transfer corona
3. Development drive mechanism
9-17
15 March 1987