The Copy Has Uneven Density (Darker At Front); The Copy Has Uneven Density (Lighter At Front) - Canon NP6621 Service Handbook

4

The copy has uneven density (darker at front).

5

The copy has uneven density (lighter at front).

Cause Step
Scanner 1 Clean the scanning lamp, reflecting
plate, side reflecting plate, mirror,
lens, and dust-proofing glass. Is the
problem corrected?
Primary 2 Execute service mode 402 (primary
charging charging roller cleaning). Is the
roller problem corrected?
Transfer 3 Execute service mode 403 (transfer
charging roller cleaning). Is the problem cor-
assembly rected?
4 Make several blank copies. Is the
problem corrected?
5 Is the transfer charging roller installed
securely?
6 Are the position and the condition of
the transfer charging roller pressure
spring normal?
Pre-expo- 7 Does the pre-exposure lamp remain
sure lamp ON during copying operation?
Developing 8 Is the developing cylinder coated with
assembly a uniform layer of toner?
Checks
IMAGE FAULTS
Yes/No Remedy
YES End.
YES End.
YES End.
YES End.
NO Install the charging roller
securely.
NO Correct or replace the spring.
NO See "The pre-exposure lamp
fails to turn ON."
NO Take out the developing
assembly, shake it several
times, and make copies. If
the Problem is not corrected,
replace the developing
assembly.
3–7