Xerox WorkCentre Pro 423 Service Manual page 258

WorkCentre Pro 423/428
Cause Corrective action
can be the cause.
• Repair or replace BTR.
Poor contact of BTR (Deformed
bias plate)
3-14 CHAPTER 3 IMAGE QUALITY TROUBLESHOOTING
C - 5 White off Copy sample
Symptom: White off
(Copies with missing or too light characters and drawings in a belt shape in the copy feed
direction at solid and halftone areas.)
Cause
BCR
• Faulty BCR
Flaws on the drum surface in
circumference direction
Toner
• Uneven toner coating on the
magnetic roll.
Foreign matter on Sheet Platen of
DADF (paper and fiber chips)
Flaws in heat roller in
circumference direction
Burrs or flaws of paper transport
system
Interrupted laser path
Partially dirty (spots) white ref. board
Control board
• Faulty MCU/SW PWB or
IIT/IPS PW
Control board
• Faulty CCD PWB
BTR is dirty.
IIT No.1-3 mirrors are dirty.
3.3 Image Quality Troubleshooting
j0hn3008
Corrective action
• Replace CRU.
• Replace HVPS.
• Replace CRU.
• Check for the cause of the drum flaws. (Foreign
matter on BTR or installation of the drum
peripherals)
• Replace CRU.
• Clean DADF glass.
• Replace Fuser.
• Check for the cause of the Heat Roller flaws.
(Deformation of Stripper Finger and installation of
the Heat Roller peripherals)
• Check paper transport system for burrs and flaws.
• Check laser path (mirror, and ROS window) from
ROS to drum for foreign matter.
• Clean the White Reference Board.
• Print out built-in Test Pattern (of continuous
gradation or 4-BITline pattern) to check and
isolate faulty board.
• Replace CCD PWB.
• Clean or replace BTR.
• Clean the mirrors.