The Copy Is Foggy (Overall) - Canon NP6621 Service Handbook

IMAGE FAULTS
6

The copy is foggy (overall).

Cause Step
1
Scanner 2
Pre-expo- 3
sure lamp,
DC control-
ler PCB
Developing 4
roll
Developing 5
cylinder
Developing 6
assembly
Drum 7
cartridge
Composite
power
supply PCB
3–8
Checks
Perform the Basic Image Adjustment
Procedure. Is the problem corrected?
Clean the scanning lamp, reflecting
plate, side reflecting plate, mirror,
lens, and dust-proofing glass. Is the
problem corrected?
Does the pre-exposure lamp remain
ON during copying operation?
Is the developing roll worn?
Is the developing cylinder worn?
Is the developing cylinder insulated
from the machine GND?
(Turn OFF the power, and disconnect
J908 of the composite power supply
PCB. Check the electrical continuity
between the developing assembly
side of J908-2 and the machine side
plate with a meter.)
Is the indication for service mode 105
(primary current indication) 10 µA or
less?
Yes/No Remedy
YES End.
YES End.
NO See "The pre-exposure lamp
fails to turn ON."
YES Replace the developing
assembly.
YES Replace the developing
assembly.
NO Check the developing
cylinder and parts around the
developing connector.
NO Replace the drum cartridge.
YES Replace the composite
power supply PCB.