Brother MFC6800 Service Manual page 150

Trouble
(5) Black and blurred vertical
stripes or band
(6) Black vertical streaks on gray
background
(7) Black and blurred horizontal
stripes
(8) Horizontal lines
At the scanner
Check the following components:
- CCD unit
At the printer side
Clean the paper path which may be contaminated with toner.
Slide the wire cleaner to clean the corona wire inside the drum
unit.
Make sure that the wire cleaner is returned to its home position.
Replace the toner cartridge.
Replace the drum unit.
Replace the heat-fixing unit.
At the printer side
Clean the laser beam window (glass) on the laser unit.
Replace the laser unit.
At the printer side
Slide the wire cleaner to clean the corona wire inside the drum
unit.
If they appear at 94-mm or 17-mm intervals, replace the drum
unit.
If they appear at 54-mm intervals, replace the heat-fixing unit.
Replace the high-voltage power supply PCB.
At the printer side
Check the connection between the right end of the paper feed
roller and the grounding wire. (Contact
given on page 6-28.)
6 -2 3
Action to be taken
in the illustration