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HP-8500 - HP8550 - COLOR LASER PRINTER - TROUBLESHOOT - PRINT FAULTS
Repetitive defects troubleshooting
Repetitive defects are defects that occur in the same
vertical position on the page, but not necessarily on every page. Most
repetitive defects are caused by problems with one of the following, and are
indicated by the positioning of the defect on the page:
Developer roller (at 38 mm)
Charging roller (at 44 mm)
Cleaning roller (at 56 mm)
Developer DSD wheels (at 65 mm)
Transfer roller (at 66 mm)
Transfer drum (occurs once per 11-by-17 inch or A3-sized
page, or every other letter- or A4-sized page)
Fuser (at 150.5 mm)
Imaging drum (at 195 mm)
Transfer belt (at 222 mm)
Color developer roller
Symptoms: Print defect occurring every 38 mm.
Cause: Dirty or damaged developer roller.
Actions: Replace the toner cartridge.
Charging roller
Symptoms: Print defect occurring every 44 mm.
Cause: Dirty or damaged charging roller.
Actions: Replace the imaging drum.
Black developer roller
Symptoms: Print defect occurring every 38 mm.
Cause: Dirty or damaged developer roller.
Actions: Replace the toner cartridge.
Cleaning roller
Symptoms: Print defects occurring every 56 mm.
Cause: Dirty or damaged cleaning roller.
Actions: Clean the cleaning roller with a hand wipe. If
cleaning does not resolve the defect, replace the cleaning roller.
Developer DSD wheels
Symptoms: Print defect occurring every 65 mm.
Cause: Dirty or damaged developer DSD wheels. These wheels
are located on the outer ends of the color toner cartridge and appear as a
black bushing.
Actions: Replace the toner cartridge of the color producing
the repetitive defect.
Transfer roller
Symptoms: Print defect occurring every 66 mm.
Cause: Dirty or damaged transfer roller.
Actions: Clean the transfer roller with isopropyl alcohol
and a hand wipe. If cleaning does not resolve the defect, replace the transfer
belt.
Transfer drum
Symptoms: Print defect occurring once per page on
11-by-17-inch-or A3-sized media, or on every other letter- or A4- sized page.
Cause: Dirty or damaged transfer drum.
Actions: Clean the transfer drums (see below). If the defect
is not resolved by cleaning, replace the transfer drum.
Cleaning the transfer drum
Many, but not all, repetitive defects can be removed using
the following procedures. Defects that appear as light spots in dark areas of
print are more likely to be corrected by this procedure than dark spots in
unprinted areas.
If the procedures are performed incorrectly or without
proper care, the transfer drum can be permanently damaged.
This procedure requires the following items:
Print sample showing the repetitive defect
Clean, flat surface on which to work
A hand wipe
You can also use a dry, clean, soft, lint-free cloth, such
as cheesecloth, to clean the transfer drum. To prevent scratches on the drum,
do not use any paper products (such as tissue or paper towels) to clean the
drum.
1 Turn the printer off and open the front door.
2 Press the button and swing the lower lever to the right.
3 Open the right upper door, and remove the transfer drum.
4 Using the print sample as a reference, inspect the transfer
drum for a spot or speck that might be causing the repetitive defects.
5 Gently rub the spot or speck with a hand wipe.
6 Re-install the transfer drum.
7 Swing the lower lever to the left making sure it clicks
into place.
8 Close the right upper and front doors, and turn the
printer on.
9 Reprint the print job. If cleaning does not eliminate the
repetitive defect, replace the transfer drum.
Do not clean the transfer drum using force. Do not use any
water-based cleaners or alcohol. These actions can permanently damage the
transfer drum.
Do not use isopropyl alcohol to clean the transfer drum.
Fuser
Symptoms: Print defects occurring at about 150.5 mm. The
defects will be most visible on overhead transparencies.
Cause: Defect on the upper fuser roller.
Actions:
1 Power the printer off, allow 30 minutes for the fuser to
cool, and remove the fuser.
2 Turn the fuser gears and inspect the surface of the upper
fusing roller. If the roller has surface defects, replace the fuser assembly.
Imaging drum
Symptoms: Print defects occurring every 195 mm.
Causes:
Damage such as scratches or dents on the imaging drum. These
usually appear as dark or light marks on the page.
Paper dust adhering to the imaging drum. These usually
appear as white marks in the dark printed areas of the page.
Exposure of portions of the imaging drum to light. This
causes dark sections in the printed output. The life of the imaging drum is
shortened by exposure to strong light.
Actions:
Print at least four configuration pages to determine if the
defect repeats in the same vertical orientation.
Inspect the imaging drum for scratches, dents, or other
damage. Replace if needed.
If the problem is dust, remove the dust with 70% isopropyl
alcohol applied with a hand wipe. Try this only if the print defect is
unacceptable and the only other alternative is replacing the imaging drum.
Defects caused by exposure to light might clear up over
time. If severe, replace the imaging drum.
Do not expose the imaging drum to direct sunlight, and be
careful not to scratch or get fingerprints on the drum surface during cleaning.
Transfer belt
Symptoms: Print defects occurring every 222 mm.
Cause: Defects on the transfer belt surface.
Actions: Remove the transfer belt and inspect the entire
belt surface.
Use the transfer belt gears to rotate the belt through its
travel.
