Xerox WorkCentre Pro 423 Service Manual page 259

Spot white off Copy sample
C - 6
Symptom: Spot white off (Copies with missing characters and drawings in spot shapes)
Cause
Moisture or wrinkle of paper
DTS contamination
Quality change or deterioration of
drum or detached OPC
Damage, quality change and
deterioration of Heat Roller surface
(at 94mm intervals)
Control board
• Faulty MCU/SYSTEM PWB or
IIT/IPS PWB
Condensation of the Platen Glass
at rear
WorkCentre Pro 423/428
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Corrective action
• Replace paper.
• Instruct the customer to store paper in dry places.
• Clean or replace DTS.
• Replace CRU.
• Replace Heat Roller.
• Print out built-in Test Pattern (4BIT line pattern) to
check and isolate faulty board.
• Clean the Platen Glass.
C - 7 Black lines Copy sample
Symptom: Black lines (Black lines of below 1mm width appear on copies in the copy feed
direction)
Cause
Drum
• Flaws on Drum surface in
circumference direction
Drum
• Poor Drum cleaning
Fuser
• Flaws on Heat Roller surface in
circumference direction
Fuser
• Too high fuser temperature
setting
Toner
• Uneven toner supply
Foreign matter on Sheet Platen of
DADF (paper and fiber chips)
Faulty reflection of White
Reference Board
Control board
• Faulty MCU/SW PWB or
IIT/IPS PWB
Control board
• Faulty CCD PWB
IIT No.1 - 3 mirrors are dirty.
3-15 CHAPTER 3 IMAGE QUALITY TROUBLESHOOTING
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Corrective action
• Replace CRU.
• Check for the cause of the Drum flaws. (Foreign
matter on BTR or installation of drum peripherals)
• Replace CRU.
• Replace Heat Roller.
• Check for the cause of the Heat Roller flaws.
(Deformation of Strip Finger and installation of
Heat Roller peripherals)
• Check NVM setup data.
(Diag: [20-100 to 106])
• Replace CRU.
• Clean DADF glass.
• Clean the White Reference Board.
• Print out built-in Test Pattern (continuous
gradation or 4-BIT line pattern) to check and
isolate faulty board.
• Replace CCD PWB.
• Clean the mirrors.
3.3 Image Quality Troubleshooting