Xerox WorkCentre Pro 423 Service Manual page 257

White off: Copy sample
C - 3
Symptom: White off (Copies with missing or too light characters and drawings in a belt
shape in the copy feed direction)
Cause
Moisture of paper
BCR
• Faulty BCR
• Faulty HVPS
Quality change and deterioration
of Drum surface
Interrupted laser path
Partially dirty white reference
board
Foreign matter (paper or fiber
chips) on Sheet Platen of DADF
Control board
• Faulty MCU/SW PWB or
IIT/IPS PWB
Control board
• Faulty CCD PWB
Toner
• Insufficient toner supply
Toner
• Toner blocking
WorkCentre Pro 423/428
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Corrective action
• Replace paper.
• Instruct the customer to store paper in dry places.
• Replace CRU.
• Replace HVPS.
• Replace CRU.
• Check for foreign matter or contamination on the
laser path (mirror, ROS window) between ROS
drum.
• Clean the white reference board.
• Remove foreign matter.
• Print out built-in Test Pattern (4BIT line pattern) to
check and isolate faulty board.
• Replace CCD PWB.
• Replace CRU.
• Replace CRU.
White off: Copy sample
C - 4
Symptom: White off
(Copies with missing or too light characters and drawings in a belt shape in the transverse
to copy feed direction)
Cause
Moisture or wrinkle of paper
Faulty BCR
Drum
• Drum revolution failure
Drum
• Quality change and
deterioration (at 94mm
intervals)
Toner
• Magnetic roll revolution failure
Developer bias
• Output failure of HVPS
Developer bias
• Magnetic roll discontinuity
Control board
• A failure occurs even when the
ROS synchronized signal from
SOS Sensor (Line Sync signal
at IPS (BSD 6.5/6.4/6.3/6.1) )
lasts longer than the specific
time and does not generate
status code [U3-3]. See BSD
6.5/6.3/6.4. SOS signal failure,
lowered ROS Power, or
revolution failure of ROS Motor
3-13 CHAPTER 3 IMAGE QUALITY TROUBLESHOOTING
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Corrective action
• Replace paper.
•
Instruct the customer to store paper in dry places.
• Replace CRU.
• Replace HVPS.
• Check for a skipping gear at CRU.
• Replace CRU.
• Check for a skipping gear at CRU.
• Replace HVPS.
• Check continuity of magnetic roll.
• Replace
ROS Assy, then IIT/IPS
(BSD 6.5/6.4/6.3/6.1)
3.3 Image Quality Troubleshooting
PWB.