Brother FAX4750 Service Manual page 190

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:
- CIS unit
At the printer side
Clean the paper path which may be contaminated with toner.
l
Slide the wire cleaner to clean the corona wire inside the
l
drum unit.
Make sure that the wire cleaner is returned to its home
l
position.
Replace the toner cartridge.
l
Replace the drum unit.
l
Replace the heat-fixing unit.
l
At the printer side
Clean the laser beam window (glass) on the laser unit.
l
Replace the laser unit.
l
At the printer side
Slide the wire cleaner to clean the corona wire inside the
l
drum unit.
If the horizontal stripes appear at 39-mm intervals, replace
l
the toner cartridge.
If they appear at 94-mm intervals, replace the drum unit.
l
If they appear at 79-mm intervals, replace the heat-fixing
l
unit.
Clean the grounding contacts. (Contacts
l
given on page VI-27.)
Replace the high-voltage power supply PCB.
l
At the printer side
Check the connection between the right end of the paper
l
feed roller and the grounding wire. (Contact
illustration given on page VI-28.)
VI - 22
Action to be taken
•
in the illustration
‡
in the