Printer Monocolor: Gradation Reproduction Failure - Konica Minolta bizhub C250 Service Manual

18. Image quality problem
18.3.19

Printer Monocolor: gradation reproduction failure

A. Typical Faulty Images
B. Troubleshooting Procedure
Step Section
Photo/Density
1
2 Imaging Unit
PH Unit
3
TCR Sensor win-
4
dow
State Confirma-
tion → Level His-
5
tory 1
(Service Mode)
Image Process
Adjustment
→Gradation
6
Adjust
(Service Mode)
Image Process
Adjustment →
7
D Max Density
(Service Mode)
Image Process
Adjustment
→ Stabilizer →
8
Reset + Stabi-
lizer
(Service Mode)
9
406
4036fs4048c0
Check Item
Original type and screen pattern are
selected properly.
Dirty on the outside.
The surface of the PH Window is
dirty.
TCR Sensor window is dirty.
IDC output value is around 4.3 V.
"Conv. Value" falls within the speci-
fied range as checked through Gra-
dation Adjust.
Max: 0 ± 100
Highlight = 0 ± 60
The problem has been eliminated
through the adjust of D Max.
After the Reset + Stabilizer
sequence has been completed, run
Gradation Adjust;
The problem has been eliminated
through the checks of steps up to 8.
Field Service Ver. 1.0 Jul. 2005
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Result Action
NO Change screen pattern.
YES Clean.
YES Clean with cleaning jig.
YES Clean.
NO Clean IDC Sensor.
Check Image Transfer Belt for
damage.
YES Go to step 9.
NO Go to next step.
NO Go to next step.
NO Change Imaging Unit.
→ Change MFP Control Board
→ Change PH Unit.
→ Change High Voltage Unit
(Image Transfer, Neutralizing).