Printer Monocolor: Gradation Reproduction Failure - Konica Minolta bizhub C650 Service Manual

18. Image quality problem
18.3.20

Printer monocolor: gradation reproduction failure

A. Typical faulty images
B. Troubleshooting procedure
Step Section
Warning display
1
Photo/density
2
3 Imaging unit
PH unit
4
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
Initialize + Image
Stabilization
(Service Mode)
9
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Check item
The maintenance call mark is
displayed on the panel.
Original type and screen pattern are
selected properly.
Dirty on the outside.
The surface of the PH window is
dirty.
IDC output value is around 4.3 V.
"Conv. Value" falls within the
specified range as checked through
gradation adjust.
Dark: 0 ± 100
Highlight: 0 ± 60
The problem has been eliminated
through the adjust of D Max.
After the Initialize + Image Stabiliza-
tion sequence has been completed,
run gradation adjust;
The problem has been eliminated
through the checks of steps up to 8.
Field Service Ver. 8.0 Jun. 2008
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Result Action
YES Take action according to the
warning code shown on the
state confirm screen.
NO Change screen pattern.
YES Clean.
YES Clean with cleaning jig.
NO Clean IDC sensor and execute
the image stabilization.
Check image transfer belt for
damage and correct as neces-
sary.
YES Go to step 9.
NO Go to next step.
NO Go to next step.
NO Change imaging unit.
→ Change printer control board
→ Change PH unit.
→ Change high voltage unit/2.