Lexmark T520 Service Manual page 118

Infoprint 1120 and 1125
FRU
5 Printhead Assembly
Print Quality - Random Marks
Service Tip: The primary cause of random marks is due to loose
material moving around inside the printer and attaching to the
photoconductor, charge roll or transfer roll.
Symptom
1 Random Marks
Print Quality - Blurred or Fuzzy Print
Blurred of fuzzy print is usually caused by a problem in the main
drive gearbox assembly, alignment assembly, any feed roller or in
the transfer roll bearings or transfer roll. Check the gearbox
assembly for correct operation. Check the transfer roll for binds or a
contaminated shaft or bearings.
Blurred print can also be caused by incorrect feeding from one of the
input paper sources, paper trays, duplex unit or envelope feeder.
Check the high voltage contacts to ensure they are not bent,
corroded or damaged. Replace as necessary.
Action
Generally a 93x service error is
posted if the printhead assembly
fails and the printer does not give a
blank copy symptom.
The printhead used in the printer
does not have a mechanical shutter
as previous laser printers. The
printer is interlocked through the
front top cover interlock switch.
Action
Check the print cartridge for any
signs of loose or foreign material that
might be on the photoconductor.
Check the transfer roll and charge
roll for any pieces of material that
are stuck to the rolls.
Diagnostic Information
2-91