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
4 TCR Sensor window
State Confirmation →
5 Level History 1
(Service Mode)
Image Process
Adjustment → Grada-
6 tion Adjust
(Service Mode)
Image Process
Adjustment → D Max
7
Density
(Service Mode)
Image Process
Adjustment → Stabi-
8
lizer → Reset + Stabi-
lizer (Service Mode)
9
496
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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. 3.0 Aug. 2006
4036fs4049c0
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).