Brother MFC8440D Service Manual page 244

7/13/2019
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 Black vertical streaks (in a gray background)
Possible cause
Translucent
stain on the
scanner window
Corona failure
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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 machine interior and the corona wire in the drum unit.
Step Check
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 machine and the
drum unit dirty?
5 Is the problem solved after
replacing the high-voltage
power supply PCB?
Step Check
1 Is there any dirt on the scanner
window?
2 Is the corona wire dirty?
Brother 8840D Service Manual
MFC-8440/8840D/8840DN, DCP-8040/8045D/8045DN
Result
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.
Result
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.
6-41
SERVICE MANUAL
Ground
Remedy
contacts
(3)
Ground
Remedy
contacts
(2)
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