Brother HL-820 Service Manual page 77

I-6 Black and blurred vertical streaks
Possible cause Step
Corona failure 1
Corona failure 2
Dirt in the paper 3
feed system
Scratch on the 4
drum
Cleaning failure 5
Scratch on the 6
heat roller
Note:
If you print the same pattern continuously, the drum will be worn and black vertical
streaks will appear on the paper.
I-7 Black and blurred horizontal stripes
Possible cause Step
Scratch on the 1
drum
Toner stuck on 2
the developer
roller
Scratch on the 3
fixing roller
High-voltage 4
power supply
PCB
Check
Is the corona wire dirty?
Is the vertical block streak
about 10mm wide?
Is the corona wire cleaner not
in its home position?
Is the paper tray or feed
system on the drum unit soiled
with toner?
Is the drum surface scratched?
Is the drum surface dirty with
toner in streaks?
Is the surface of the heat roller
scratched?
Check
Are the horizontal stripes at
94mm (OPC drum) intervals?
Are the horizontal stripes at
25mm (developer roller)
intervals?
Are the horizontal streaks at
63mm (heat roller) intervals?
Is the problem solved after the
high-voltage power supply
PCB is replaced?
IV-10
Result Remedy
Yes Clean the corona
wire with the wire
cleaner.
Yes Return the wire
cleaner to its home
position.
Yes Clean the toner off.
Yes Replace the drum
unit.
Yes Replace the drum
unit.
Yes Replace the fixing
unit.
Result Remedy
Yes Replace the drum unit.
Yes Print several sheet and see
what happens.
The problem will disappear
after a while. If not, replace the
drum unit.
Yes Replace the fixing unit.
Yes Replace the high-voltage
power supply PCB.
HV.GND
contacts
(Fig.4-5)