The Copy Has Uneven Density - Canon NP7160 Service Manual

4. The copy has uneven density. (front side dark)
5. The copy has uneven density. (front side light)
Cause Step
Developing
assembly
Scanner
Pre-scanning lamp
(LA2)
Developing
assembly
Charging assembly,
Copy paper
COPYRIGHT © 1998 CANON INC.
Checks
1 Perform the Image Adjustment Basic
Procedure. Is the problem corrected?
2 Are the developing rolls of the
developing assembly in firm contact
with the photosensitive drum?
Clean the scanning lamp, reflecting
3
plate, side reflecting plate, mirror,
lens, and dust-proofing glass. Is the
problem corrected?
4 Does the pre-exposure lamp remain
on during copying?
5 Is the developing cylinder coated
with a uniform layer of toner?
CANON NP7161/NP7160 REV.0 AUG. 1998 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 10 TROUBLESHOOTING
Yes/No Actions
YES End.
NO Check the developing assembly
locking lever.
YES End.
NO 1. Replace the pre-exposure lamp.
2. Replace the DC controller PCB.
NO 1. Clean the tip of the blade of the
developing assembly. (dry wiping)?
2. Clean the surface of the developing
cylinder.
3. Check to make sure that the toner
inside the developing assembly is
not displaced to one side.
YES 1. Clean all charging wires once
again, and check the height of the
charging wires once again.
2. Try replacing the copy paper.
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