Brother HL-5240 Service Manual page 159

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