Brother MFC-8460N Service Manual page 358

(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 the inside of the machine 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 4
contact failure
High-voltage 5
power supply
PCB failure
(I-8) Black vertical streaks (in a gray background)
Possible cause
Step
Corona failure 1
User Check
Check
Are the horizontal stripes at
74mm (exposure drum)
intervals?
Are the horizontal stripes at
42.7mm (developer roller)
intervals?
Are the horizontal stripes at
79mm (heat roller)
intervals?
Are the charge electrodes
between the machine body
and the drum unit dirty?
Is the problem solved after
replacing the high-voltage
power supply PCB?
Check
Is the corona wire dirty?
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 heat roller.
Yes Clean both electrodes.
Yes Replace the high-
voltage power supply
PCB.
Result
Yes Clean the corona wire
with the wire cleaner.
9-35
Ground
Remedy
contacts
(3)
Ground
Remedy
contacts
(2)
Confidential