Xerox WorkCentre Pro 423 Service Manual page 261

Belt high-background Copy sample
C - 10
Symptom: Belt high-background (Belt like images appearing in the copy feed direction.
Belt width exceeds 1mm and light one is called belt high background while dark one is
called black belt.)
Cause
Faulty BCR
Drum
• Poor Drum cleaning
Drum
• Contamination, quality change,
and deterioration of Drum
Drum
• Uneven toner thickness
Dirty Platen Glass
HVPS
• Output failure of HVPS, and
contact failure of terminals
Control board
• Faulty MCU/SW PWB or IPS
PWB
(When shading
compensation fails, high
background appears at both
sides.)
Control board
• Faulty CCD PWB
Fuser
• Contamination, quality change
and deterioration of
Heat/Pressure Roller
WorkCentre Pro 423/428
j0hn3013
Corrective action
• Replace CRU.
• Replace CRU.
• Replace CRU.
• Replace CRU.
• Clean Platen Glass.
• Clean DADF Glass.
• Replace HVPS, check continuity.
• Print out built-in Test Pattern (continuous
gradation or line pattern) to check and isolate
faulty board.
• Replace CCD PWB.
• Clean/replace the appropriate roller.
Belt high-background Copy sample
C - 11
Symptom: Belt high-background (Belt like images appearing in the transverse to copy feed
direction. Belt width exceeds 1mm and light one is called belt high background while dark
one is called black belt.)
Cause
Faulty BCR
Drum
• Poor cleaning of Drum
Drum
• Contamination, quality change
and deterioration of Drum
Drum
• Faulty grounding of Drum
Dirty Platen Glass
Control board
• Faulty MCU/SW PW or IIT/IPS
PWB
HVPS
• Output failure of HVPS, and
contact failure of terminals
BTR
• BTR failure (at 55mm intervals)
Fuser
• Contamination, quality change
and deterioration
Heat/Pressure Roller (at 94mm
intervals)
3-17 CHAPTER 3 IMAGE QUALITY TROUBLESHOOTING
j0hn3014
Corrective action
• Replace CRU.
• Replace CRU.
• Replace CRU.
• Check continuity path of Drum grounding.
• Clean Platen Glass.
• Print out built-in Test Pattern (line pattern) to
check and isolate faulty board.
• Replace HVPS, and check continuity.
• Replace BTR.
• Clean/Replace the appropriate roller.
of
3.3 Image Quality Troubleshooting