HL-5240/5250DN/5270DN/5280DW SERVICE MANUAL
Confidential
4-45
(I-7) Black and blurred horizontal stripes
Possible cause
Step
Check
Result
Remedy
Ground
contacts
Scratch on the
drum
1
Are the horizontal stripes at
74mm (exposure drum)
intervals?
Yes
The exposure drum
was scratched.
Replace the drum
unit.
Toner stuck on
the developer
roller
2
Are the horizontal stripes at
62.8mm (developer roller)
intervals?
Yes
After printing several
pages, the problem
will disappear.
If not, replace the
toner cartridge.
Scratch on the
heat roller
3
Are the horizontal stripes at
79mm (heat roller) intervals?
Yes
Replace the fuser unit.
Corona contact
failure
4
Are the charge electrodes
between the printer body and
the drum unit dirty?
Yes
Clean both electrodes.
High-voltage
power supply
PCB failure
5
Is the problem solved after
replacing the high-voltage
power supply PCB?
Yes
Replace the high-
voltage power supply
PCB.
(I-8) Black vertical streaks (in a gray background)
Possible cause
Step
Check
Result
Remedy
Ground
contacts
Translucent
stain on the
scanner window
1
Is there any dirt on the scanner
window?
Yes
1) Clean the scanner
window.
2) If it is not effective,
replace the laser
unit.
Corona failure
2
Is the corona wire dirty?
Yes
Clean the corona wire
with the wire cleaner.
User Check
(1) The drum unit may be damaged. Install a new drum unit.
(2) Check the paper used meets the recommended paper specifications.
(3) Clean inside of the printer and the corona wire in the drum unit.