Canon NP6621 Service Handbook page 57

10 The copy has white spots (vertical).
11 The copy has white lines (vertical).
Cause Step
Fixing 1 Press the Copy Start key with the
assembly copyboard open, and turn OFF the
power switch while the copy is moving
through the feeding assembly. At this
time, does the copy before the fixing
assembly have white spots or lines?
Primary 2 Execute service mode No. 402
charging (primary charging roller cleaning). Is
roller the problem corrected?
Transfer 3 Execute service mode 409 (transfer
charging roller cleaning). Is the problem cor-
roller rected?
4 Is there dirt, cracks, or scratches on
the transfer charging roller?
5 Are the position and the condition of
the transfer charging roller pressure
spring normal?
Static 6 Clean the static eliminator. Is the
eliminator problem corrected?
Developing 7 Is the density of the toner on the
assembly developing cylinder even?
Copy paper 8 Try fresh copy paper. Is the problem
corrected?
Photosensi- 9 Are there scratches around the
tive drum surface of the photosensitive drum?
External
light
Checks
IMAGE FAULTS
Yes/No Remedy
NO 1. Clean the inlet guide
assembly (upper, lower)
of the fixing assembly.
2. Check the upper fixing
roller.
3. Check and clean the
separation claws.
YES End.
YES End.
YES Replace the transfer charg-
ing roller.
NO Correct or replace the spring.
YES End.
NO Shake the developing
assembly several times. If
the problem is not corrected,
replace the developing
assembly.
YES The paper may be moist;
advise the user on the
correct method of storing
paper.
YES Replace the drum cartridge.
(Be sure to find out the
cause of scratches.)
NO Check the photosensitive
drum to find out if it is subject
to external light.
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