Brother MFC-B7720DN Service Manual

2-87
Confidential
 Completely blank
 Image distortion
<User Check>
• Replace the drum unit with a new one.
• Replace the toner cartridge with a new one.
• Install the latest main firmware.
Step Cause Remedy
1
Connection failure of the laser
unit flat cable
Reconnect the laser unit flat cable.
2 Laser unit attachment failure Reattach the laser unit.
3 Laser unit flat cable failure Replace the laser unit flat cable.
4
Dirt on the electrodes of the
high-voltage power supply
PCB and those of the
machine
Clean the electrodes of the high-voltage
power supply PCB and those of the machine.
5 Laser unit failure Replace the laser unit.
6 Main PCB failure Replace the main PCB ASSY.
Step Cause Remedy
1 Laser unit attachment failure Reattach the laser unit.
2 Laser unit failure Replace the laser unit.
3 Main PCB failure Replace the main PCB ASSY.

Brother MFC-B7720DN Specifications

General

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