Canon NP6251 Service Manual page 604

6. The copy is foggy. (overall)
Cause Step
LIGHT_5
Scanner
Cleaner
assembly
Pre-exposure
lamp, DC
controller PCB
Developing roll
Developing
cylinder
Lamp regulator
Potential control
system
DC controller
PCB
High-voltage
transformer,
Developing
assembly
COPYRIGHT © 1997 CANON INC.
Checks
1 Perform the Image Adjustment
Basic Procedure. Is the problem
corrected?
2 Clean the scanning lamp,
reflecting plate, side reflecting
plate, mirror, lens, dust-proofing
glass, and heat absorbing glass.
Is the problem corrected?
3 Is the cleaning blade installed
correctly?
4 Is the pre-exposure lamp flashing
during copying?
5 Are the developing rolls worn?
6 Replace the developing cylinder.
Is the problem corrected?
7 Replace the lamp regulator. Is the
problem corrected?
8 Make the checks on p. 11-42. Is
the potential sensor normal?
9 Set the meter to the 30VDC
range, and measure the voltage
between J111A-2 (DCBC) and
J114A-13 (GND) on the DC
controller PCB.
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 11 TROUBLESHOOTING
YES/NO Action
YES End.
YES End.
NO Install the cleaning
blade.
NO 1. Replace the pre-
exposure lamp.
2. Replace the DC
controller PCB.
YES Replace the developing
rolls.
YES Replace the developing
cylinder.
YES End.
YES Replace the DC
controller PCB.
NO Replace the DC
controller PCB.
YES 1. Check the wiring from
the DC controller PCB
and the high-voltage
transformer; if normal,
replace the high-
voltage transformer.
2. Check the developing
assembly.
11-73