Brother MFC-9320CW Service Manual page 164

■ Unstable color density
<User Check>
- Make a print on a different type of paper.
- Replace the belt unit with a new one.
- Replace the drum unit with a new one.
- Replace the waste toner box with a new one.
- Replace the toner cartridge with a new one.
Step Cause
1 Drum unit
conduction failure
2 Toner cartridge
conduction failure
3 Dirt on belt unit
electrode
4 Engine PCB failure
5 HVPS control PCB
failure
6 High-voltage power
supply PCB failure
7 LED head control
PCB failure
8 Main PCB failure
Check
Are the electrodes on
the drum unit and
machine body dirty?
Are the electrodes on
the toner cartridge and
machine body dirty?
Are the electrodes on
the belt unit and
machine body dirty?
Is the problem solved
after replacing the
engine PCB ASSY?
Is the problem solved
after replacing the HVPS
control PCB ASSY?
Is the problem solved
after replacing the
high-voltage power
supply PCB ASSY?
Is the problem solved
after replacing the LED
head control PCB ASSY?
Is the problem solved
after replacing the main
PCB ASSY?
3-83
Remedy
Result
Yes Clean both electrodes.
(Refer to Fig. 3-3 (P3-32)
and Fig. 3-6 (P3-33))
Yes Clean both electrodes.
(Refer to Fig. 3-3 (P3-32)
and Fig. 3-6 (P3-33))
Yes Clean both electrodes.
(Refer to Fig. 3-4 (P3-32)
and Fig. 3-6 (P3-33))
Yes Replace the engine
PCB ASSY.
Yes Replace the HVPS
control PCB ASSY.
Yes Replace the
high-voltage power
supply PCB ASSY.
Yes Replace the LED head
control PCB ASSY.
Yes Replace the main PCB
ASSY.
Confidential