Printer Monocolor: White Lines, White Bands, Colored Lines And Colored Bands In Sub Scan Direction - Konica Minolta bizhub C25 Service Manual

22. IMAGE QUALITY PROBLEM
22.2.12 Printer monocolor: white lines, white bands, colored lines and colored
bands in sub scan direction
A. Typical faulty images
White lines
B. Troubleshooting procedure
Step Section
1 Image check A white line or black line in sub
scan direction is sharp.
2 When printing thick paper, black
lines appear.
3 Imaging unit The surface of the PC drum is
scratched.
4 Dirty on the outside.
5 Contact terminals make good con-
nection between each imaging unit
and machine.
6 Developing bias contact terminal
makes good connection.
7 PH unit The surface of the PH window is
dirty.
8 The problem has been eliminated
through the checks of steps up to 7.
356
White bands Colored lines
Check item Result
YES Clean the electrostatic charger wire.
YES Select [SERVICE MODE] 
YES Change imaging unit.
YES Clean.
YES Clean with cleaning jig.
Field Service Ver. 1.1 May 2011
Colored bands
Action
[ADJUST]  [THICK MODE] and set
[QUALITY MODE].
NO Clean contact terminals.
NO Clean contact terminal and check ter-
minal position.
NO Change transfer belt unit.
Change PH unit.
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