Printer Monocolor: Uneven Density In Sub Scan Direction - Konica Minolta bizhub C650 Service Manual

18. Image quality problem
18.3.17

Printer monocolor: uneven density in sub scan direction

A. Typical faulty images
B. Troubleshooting procedure
Step Section
High image
density original
1
Machine
→ LD adjust-
ment → LD
2
lightness bal-
ance adjust.
(Service Mode)
Imaging unit
3
4
PH unit
5
Transfer belt
6
unit
7
710
4036fs4043c0
Check item
Uneven density in sub scan direc-
tion occurs at a pitch of 40 mm to
50 mm when a multi-copy cycle is
run using an original with high
image density (50% or more).
The problem has been eliminated
through the LD lightness balance
adjust.
The surface of the PC drum is
scratched.
Dirty on the outside.
The surface of the PH window is
dirty.
Is abnormality found in the cam
gear?
The problem has been eliminated
through the checks of steps up to 6.
Field Service Ver. 8.0 Jun. 2008
4036fs4044c0 4036fs4045c0
Result
YES Feed 10 to 20 blank sheets of
paper with no originals placed, as
the IU fails to keep up with a high
demand for toner.
NO Go to next step.
YES Change imaging unit.
YES Clean.
YES Clean with cleaning jig.
YES Change transfer belt unit.
NO Change IU.
→ Change PH unit.
→ Change High voltage unit/2.
Action