The Copy Has Uneven Density (Front Too Dark); The Copy Has Uneven Density (Front Too Light) - Canon NP6218 Service Manual

CHAPTER 10 TROUBLESHOOTING

4. The copy has uneven density (front too dark).

5. The copy has uneven density (front too light).

Cause Step
Scanner
Primary
charging roller
Transfer charg-
ing assembly
Pre-exposure
lamp
Developing
assembly
10-52
Checks
1 Clean the scanning lamp, reflect-
ing plate, side reflecting plate,
mirror, lens, and dust-proofing
glass. Is the problem corrected?
2 Execute 'No. 402' in service mode
(primary charging roller cleaning).
Is the problem corrected?
3 Execute 'No. 403' in service mode
(transfer roller cleaning). Is the
problem corrected?
4 Make several blank (white) copies.
Is the problem corrected?
5 Is the transfer changing roller
securely inserted?
6 Are the position and condition of
the pressure spring of the transfer
charging roller normal?
7 Does the pre-exposure lamp turn
on during copying operation?
8 Is the developing cylinder coated
with a uniform layer of toner?
COPYRIGHT © 1997 CANON INC.
Results
YES
YES
YES
YES
NO
NO
NO
NO
CANON NP6218 REV. 0 MAY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
Action
End.
End.
End.
End.
Re-insert the charging
roller.
Corrector replace the
spring.
See "The pre-exposure
lamp fails to turn on."
Take out the developing
assembly, and shake it
several times; then,
make copies. If the
problem is not corrected,
replace the developing
assembly.