Printer Monocolor: Uneven Density In Sub Scan Direction - Konica Minolta bizhub C250 Service Manual

18. Image quality problem
18.3.16

Printer Monocolor: uneven density in sub scan direction

A. Typical Faulty Images
B. Troubleshooting Procedure
Step Section
High image density
original
1
Imaging Unit
2
3
PH Unit
4
Image Transfer Belt
5
Unit
6
492
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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 surface of the PC Drum is
scratched.
Dirty on the outside.
The surface of the PH Window is
dirty.
Cam gear operates properly.
The problem has been eliminated
through the checks of steps up to 5.
Field Service Ver. 3.0 Aug. 2006
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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.
YES Change Imaging Unit.
YES Clean.
YES Clean with cleaning jig.
NO Change Image Transfer
Belt Unit.
NO Change IU.
→ Change PH Unit.
→ Change High Voltage
Unit (Image Transfer,
Neutralizing).
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Action