Canon NP6251 Service Manual page 606

9. The copy has black lines (vertical, fine).
Cause Step
Copyboard
glass
Photosensitive
drum cleaner
assembly
Photosensitive
drum
Developing
system,
Exposure
system
Fixing assembly
COPYRIGHT © 1997 CANON INC.
Checks
1 Dese the problem occur only in
stream reading mode?
2 Press the Copy Start key, and turn
off the power switch when copy
paper is in the feeding assembly.
At this time, does the copy before
moving through the fixing
assembly have black lines?
3 Is paper or foreign matter trapped
on the cleaning blade of the
cleaner assembly?
4 Are there scratches on the
cleaning blade? (Feel the edge of
the cleaning blade with a finger to
find out.)
5 Are there scratches or black lines
on the surface of the
photosensitive drum in the
peripheral direction?
6 Are there scratches or black lines
on the surface of the fixing
assembly upper roller in the
peripheral direction?
CANON NP6350/NP6251 REV. 0 JULY 1997 PRINTED IN JAPAN (IMPRIME AU JAPON)
CHAPTER 11 TROUBLESHOOTING
YES/NO Action
YES Check the copyboard
glass for dirt and
scratches at the point
where the scanner is
fixed in position in
stream reading mode.
NO Go to step 6.
YES Remove the foreign
matter, and clean the
cleaning blade and the
outside of the cleaner
assembly.
YES Switch to the new side
(edge). If both edges
have scratches, find out
the cause.
YES Replace the
photosensitive drum. If
scratches are found, find
out the cause.
NO Check the developing
system and the
exposure system.
YES 1. Replace the upper
roller.
2. Check the take-up
mechanism for the
cleaning belt.
3. Check the reciprocat-
ing mechanism of the
thermistor and the
separation claw.
Check the inlet of the
NO
fixing assembly for dirt.
11-75