Service manual

COPYRIGHT © 1999 CANON INC. CANON GP160 REV.0 FEB. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 13 TROUBLESHOOTING
13-18
1 Too Light
Cause
Copy paper
Cartridge
Poor connector
connection
Cartridge
(primary charg-
ing roller)
Laser scanner
unit
DC controller
PCB
Transfer guide
Transfer charg-
ing roller con-
tact
Transfer charg-
ing roller
Dirty scanner
assembly
Steps
1
2
3
4
5
6
7
8
9
10
Yes/No
YES
NO
YES
YES
NO
YES
YES
NO
NO
YES
NO
YES
Action
1. The paper may be
damp. Advise the
user on paper stor-
age methods.
2. If paper other than
the recommended
paper is being used,
explain to the user
that this may cause
an inferior image.
Check from Step 10.
Check from Step 8.
End
Connect firmly.
End
End
Replace the DC con-
troller PCB
Check that no screws
or other metal parts
have fallen near the
transfer guide.
Clean the contacts.
Replace the transfer
charging roller.
End
Checks
When new (unopened) copy paper is
used, does the density become
darker?
Make a test print following the direc-
tions on page 13-120. Is the output
image too light?
Interrupt and stop the machine while
the image is being printed onto pho-
tosensitive drum. Is the toner being
developed on the drum surface?
Remove the cartridge. Does the
problem improve after the cartridge
has been lightly shaken 5 or 6
times?
Check the connection between con-
nector J304 on the DC controller
PCB and the laser scanner unit. Is it
normal?
Is the trouble resolved when the car-
tridge is replaced?
Is the trouble resolved when the
laser scanner unit is replaced?
When the transfer guide and other
metal parts are measured by a
tester, is the electrical resistance 0
ohms?
Check the transfer charging roller
and the high voltage contact point.
Are they dirty?
Does the image improve when the
mirror and lens dust proof glass are
cleaned?
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