C4170-90959
Image Formation Troubleshooting
121
Dark Print
Possible Cause Action
Poor contact between
the drum grounding
contact pin of the
drive unit and the
cartridge contact.
Clean the contacts. Replace the contacts if the
problem persists after cleaning.
Poor contact between
the primary bias
contact on the Engine
Controller Assembly
and the cartridge
contact
Clean the contacts. Replace the contacts if the
problem persists after cleaning.
Defective Laser
Scanner
Replace the Laser Scanner.
Defective Engine
Controller Assembly
Replace the Engine Controller Assembly and the
Intermediate PCB.
Dirt on Back
Possible Cause Action
Particles accumulate
over time inside
printer (Tray
Separation Roller,
Feed Roller, Transfer
Roller, Fuser, Toner
Cartridge).
1) Print at least 10 pages to see if the problem goes
away.
2) Print a cleaning page. See “To Start Engine
Cleaning” (page 62).
Identify and clean the dirty part according to the
“Repetitive Defect Ruler” (page 132). If dirt cannot
be removed, replace the dirty part.
3) Check for toner leaks.
Paper does not meet
printer specifications
or is stored
improperly.
1) Print a few more pages to see if the problem
corrects itself.
2) Turn over the stack of paper in the tray. Also try
rotating the paper 180 degrees.
3) Check the paper (or other print media) type and
quality. Replace the paper, and advise the customer
to use the recommended paper and store it properly.
See “Media Troubleshooting” (page 134).
Dirt on an internal
roller
Use the “Repetitive Defect Ruler” (page 132) to
determine the dirty roller. Clean or replace it.
Dirty feed belt, feed
guide, or fuser
entrance guide
Clean the dirty areas.
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