Printer Monocolor: Foggy Background - Konica Minolta bizhub C450 Service Manual

Field Service Ver. 1.0 Mar. 2005
18.3.19

Printer Monocolor: foggy background

A. Typical Faulty Images
B. Troubleshooting Procedure
Step Section
State Confirma-
tion → Table
1 Number
(Service Mode)
2 State Confirma-
tion → Level His-
tory 1
3
(Service Mode)
4 Level History data
check results
5
6
7
LPH Assy
8
9 Imaging Unit
10 LPH Assy
TCR Sensor win-
11
dow
Image Process
Adjustment →
12 Background Volt-
age Margin
(Service Mode)
Image Process
Adjustment
→Gradation
13
Adjust
(Service Mode)
ABCD
ABCD
ABCD
ABCD
ABCD
4036fs4030c0
Check Item
Check data for Vg and Vb.
Color Vdc: Around 390 V
Vg : Around 500 V
Black Vdc: Around 390 V
Vg : Around 500 V
Check TCR data.
IDC output value is around 4.3 V.
Low TCR and low Vg and Vdc
Low TCR and high Vg and Vdc
TCR falling within specified range
and low Vg and Vdc
TCR falling within specified range
and high Vg and Vdc
LED retracting lever is locked in
position.
Dirty on the outside.
The surface of the lens array is dirty.
The color TCR Sensor window on
the LED Assy is dirty.
The problem is eliminated after
Background Voltage Margin has
been adjusted.
"Conv. Value" falls within the speci-
fied range as checked through Gra-
dation Adjust.
Max: 0 ± 100
Highlight = 0 ± 60
18. Image quality problem
Result Action
NO Go to next step.
NO Go to next step.
NO Clean IDC Sensor.
Check Transfer Belt for dam-
age.
YES Go to step 8.
YES Go to step 12.
YES Go to step 8.
YES Go to step 12.
NO Slide out the IU and reinstall.
YES Clean.
YES Clean with cleaning jig.
YES Clean.
NO Go to next step.
YES Go to step 17.
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