The Copy Has Uneven Density - Canon NP6330 Service Manual

Step
Cause
10
Drum unit
High-voltage
cord, high-
voltage power
supply PCB,
DC controller
PCB
4 The copy has uneven density. (darker at front)
5 The copy has uneven density. (lighter at front)
Step
Cause
1
Scanner
2
Transfer 3
charging
assembly
4
5
Pre-exposure
lamp
6
Developing
assembly
Charging wire,
copy paper
COPYRIGHT © 1997 CANON INC.
Checks
Replace the drum unit. Is the
problem corrected?
Checks
Clean the scanning lamp, reflect-
ing plate, side reflecting plate,
mirror, lens, and dust-proofing
glass. Is the problem corrected?
Perform the Image Adjustment
Basic Procedure. Is the problem
corrected?
Is the transfer charging assembly
set securely?
Is the charging wire of the transfer
charging assembly hooked
properly, and is its height normal?
Is the pre-exposure lamp on
during copying operation?
Is the coating of toner on the
developing cylinder even?
CANON NP6330 REV.0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 11 TROUBLESHOOTING
YES/NO Action
YES End.
NO 1. Check the high-
voltage cord for
electrical continuity.
2. Check the high-
voltage power supply
PCB and the DC
controller PCB
YES/NO Action
YES End.
YES End.
NO Set the charging
assembly securely.
NO Re-string the charging
wire.
NO See "The pre-exposure
lamp fails to turn on."
NO • Check the edge of the
blade of the developing
assembly.
• Dry wipe the surface of
the developing cylinder.
YES • Clean all charging
wires once again, and
check their position.
• Try replacing the copy
paper.
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