Troubleshooting for Image Quality Problems
D0CA/D0C9/D0C8/D0CB 6-144 SM
Test pattern check Possible cause/Countermeasure
2. Replace the high-voltage power supply unit
(PCB22)(PCB23).
3. Do the forced process control (SP3-011-001) or supply
some toner (SP3-030-xxx).
4. Replace the BiCU (PCB1).
Normal image, but with color
registration errors
1. Defective ID sensor shutter
2. Defective ID sensors (S27-S29)
3. Defective BiCU (PCB1)
1. Replace the ID sensor shutter solenoid (SOL2).
2. Replace the ID sensors (S27-S29).
3. Replace the BiCU (PCB1).
After Executing SP2-111-001
• Result: "1" in SP2-194-007
• Result: "5" (Out of adjustable range) in SP2-194-010, -011, -012
Test pattern check Possible cause/Countermeasure
Low image density on the output
• Low pattern density
Do the forced process control (SP3-011-001)
or supply some toner (SP3-030-xxx).
The main scan registrations of M, C, Y, K are
shifted by more than ±1.4.
• Defective laser optics housing unit
• Defective BiCU (PCB1)
1. Do SP2-111-003 again.
2. Replace the laser optics housing unit.
3. Replace the BiCU (PCB1).
The sub scan registrations of M, C, Y are shifted
by more than ±1.4mm from the sub scan
registration of K.
• Defective image transfer belt
• Defective drive units
• Defective BiCU (PCB1)
1. Do SP2-111-003 again.
2. Replace the image transfer belt.
3. Replace the drum motor (M10,M11).
4. Replace the BiCU (PCB1).
The main scan registration is shifted by more than
±0.66 mm, but only at the central area of the
image on the output.
• Defective ID sensor (S28) at center
• Deformed center area on the image
transfer belt
• Defective BiCU (PCB1)
1. Replace the ID sensors (S27-S29).
2. Replace the image transfer belt.
3. Replace the BiCU (PCB1).
The skew for M, C, Y, K is more than ± 0.75 mm at
• Defective PCDU
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