The Copy Has Uneven Density (Darker Front); The Copy Has Uneven Density (Lighter Front) - Canon iR8500 Service Manual

CHAPTER 6 TROUBLESHOOTING

3.3.4 The copy has uneven density (darker front)

3.3.5 The copy has uneven density (lighter front)

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1) Perform the Image Adjustment Basic Procedure. Is the problem
YES: End.
Developing assembly (position)
2) Are the developing members of the developing assembly in firm
NO:
Scanner (dirt)
3) Clean the scanning lamp, reflecting plate, side reflecting plate, mir-
YES: End.
Pre-exposure lamp
4) Is the pre-exposure lamp ON evenly during printing operation?
NO:
Developing assembly, Charging assembly, Paper
5) Is the developing cylinder coated evenly with toner?
NO:
YES: 1. Clean all the charging wires once again, and check the position
6-80
corrected?
contact with the photosensitive drum?
Check the developing assembly locking unit.
ror, lens, and dust-proofing glass. Is the problem corrected?
1. Replace the pre-exposure lamp.
2. Replace the DC controller PCB.
1. Clean the tip f the blade of the developing assembly (dry wip-
ing).
2. Clean the surface of the developing cylinder.
3. Check to find out if the toner inside the developing assembly is
uneven.
of each charging wire.
2. Try different paper.
3. Check the nip width of the fixing roller.
COPYRIGHT© 2001 CANON INC. 2000 2000 2000 2000 CANON iR8500/7200 REV.1 AUG. 2001