Brother DCP-7090 Service Manual page 136

 Downward fogging of solid color
<User Check>
Step
High-voltage power supply
1
PCB failure
2 Main PCB failure
 Horizontal lines
Step
Dirty charge electrodes
1
Dirt on the exposure drum
2
Scratch or dirt on the fuser
3
unit
High-voltage power supply
4
PCB failure
• Replace the toner cartridge with a new one.
Cause
<User Check>
• This problem may disappear after printing multiple
sheets of paper.
• Refer to
dirt from the exposure drum using a cotton applicator.
• Replace the drum unit with a new one.
• Replace the toner cartridge with a new one.
Cause
2-96
Remedy
Replace the high-voltage power supply PCB
ASSY.
Replace the main PCB ASSY.
<How to clean the drum unit>
Remedy
Clean the electrodes of the drum unit and
those of the machine. (Refer to
56) and Fig. 2-12 (P2-56).)
Perform drum cleaning.
(Refer to "2.1 Drum Cleaning" in Chapter
Replace the fuser unit.
Replace the high-voltage power supply PCB
ASSY.
to remove the
Fig. 2-13 (P2-
5.)
Confidential