Canon NP6251 Service Manual page 602

Cause Step
Lower
transfer
guide/varistor
DC controller
PCB
Developing
assembly
Pre-transfer
charging
assembly
10
Potential 11
control,
Photosensitive
drum
Developing bias
control
COPYRIGHT © 1997 CANON INC.
Checks
7 Measure the resistance between
the PCBs (metal sections) of the
lower transfer guide and the
feeding assembly. Is it 0 ?
8 Is the developing assembly set
securely? Are the rolls of the
developing assembly in firm con-
tact with the photosensitive drum?
9 Is the pre-transfer charging wire
hooked correctly and is its height
correct?
Is the pre-transfer charging
assembly set correctly?
Turn off and then on the power
switch, and check the readings of
'VD' and 'VL1' in service mode (
). Are the readings of 'VDM'
1
and 'VL1M' the target value (VDT,
VL1T) ±10V?
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 11 TROUBLESHOOTING
YES/NO Action
YES 1. Check to see if the
transfer guide should
be in contact with the
side plate of the
feeding assembly
(metal section).
2. Replace the varistor.
NO Check the high-voltage
transformer (HVT) and
the DC controller PCB.
NO Check the developing
assembly locking unit.
NO 1. Hook the charging
wire correctly.
2. Adjust the height of
the charging wire.
NO 1. Clean the charging
wire.
2. Set the charging
assembly securely.
NO Check the potential
control system; if normal,
replace the
photosensitive drum.
YES Check the developing
bias control system.
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