Canon NP6621 Service Handbook page 63

20 The copy has poor sharpness.
Cause Step
Original 1 Is the original off the copyboard glass?
Lens drive 2
Is the copyboard glass stained with
assembly
oil? Further, is the copyboard installed
correctly?
Lens drive 3 Turn OFF and then ON the power
assembly switch. Does the lens move smoothly?
Transferf 4 Execute 'No. 403' in service mode
charging (transfer charging roller cleaning). Is
roller the problem corrected?
5 Is the transfer charging roller installed
securely?
6
Is there dirt, cracks, or scratches on
the transfer charging roller?
7
Are the position and the condition of
the transfer roller pressure spring
normal?
Drum 8 Is the drum cartridge installed se-
cartridge, curely? (Check if the developing
Developing assembly roll is forced against the
assembly photosensitive drum.)
Developing 9 Is the developing bias generated
bias normally?
Mirror 10
Is the horizontal reproduction ratio in
position
DIRECT copying within specification?
Scanner
Checks
IMAGE FAULTS
Yes/No Remedy
YES 1. Check the copyboard
cover for warping.
2. Advise the user how to
place an original on the
copyboard correctly.
YES • Clean the copyboard glass.
• Install the copyboard glass
correctly.
NO Check the lens drive assem-
bly.
YES End.
NO Install the transfer charging
roller securely.
YES Replace the transfer charging
roller.
NO
Correct or replace the spring.
NO Install the drum cartridge and
developing assembly once
again.
NO Replace the composite power
supply. (Replace the DC
controller PCB.)
NO Adjust the distance between
No. 1 mirror mount and No. 2
mirror mount.
YES
Clean the scanning lamp,
reflecting plate, mirror, lens,
and dust-proofing glass.
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