Brother HL 1240 - B/W Laser Printer Service Manual page 140

CHAPTER 6 TROUBLESHOOTING
I-7 Black and blurred horizontal stripes
Possible cause
Scratch on the
drum
Toner stuck on
the developer
roller
Scratch on the
heat roller
Corona contact
failure
High-voltage
power supply
PCB failure
I-8
Possible cause
Translucent
stain on the
scanner window
Corona failure
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 the printer interior and the corona wire in the drum unit.
Step
1 Are the horizontal stripes at
94mm (photosensitive drum)
intervals?
2 Are the horizontal stripes at
39mm (developer roller)
intervals?
3 Are the horizontal stripes at
79mm (heat roller) intervals?
4 Are the charge electrodes
between the printer body and
the drum unit dirty?
5 Is the problem solved after
replacing the high-voltage
power supply PCB?
Black vertical streaks (in a gray background)
Step
1 Is there any dirt on the scanner
window?
2 Is the corona wire dirty?
Check Result
Check Result
6-30
Remedy
Yes The photosensitive
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 heat
roller.
Yes Clean both electrodes.
Yes Replace the high-
voltage power supply
PCB.
Remedy
Yes 1) Clean the scanner
window.
2) If it is not effective,
replace the laser
unit.
Yes Clean the corona wire
with the wire cleaner.
Ground
contacts
Ground
contacts