Brother MFC-B7720DN Service Manual

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

Brother MFC-B7720DN Specifications

General

Brand	Brother
Model	MFC-B7720DN
Category	All in One Printer
Language	English