Brother MFC-9320CW Service Manual page 145

■ Dark
<User Check>
- Check the machine's environment. High temperature and high humidity
- Clean the corona wire.
- Replace the toner cartridge or drum unit with a new one.
- Adjust the color density from the control panel cover ASSY.
Step Cause
1 Corona wire
conduction failure
2 Dirt on belt unit
electrode
3 HVPS control PCB
failure
4 High-voltage power
supply PCB failure
5 Engine PCB failure
6 Main PCB failure
7 LED head control
PCB failure
8 Registration mark L
PCB failure
9 Toner/new
sensor PCB failure
or low temperature and low humidity conditions can cause this problem.
Are the electrodes on
the drum unit and
machine body dirty?
Are the electrodes on
the belt unit and
machine body dirty?
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
engine PCB ASSY?
Is the problem solved
after replacing the main
PCB ASSY?
Is the problem solved
after replacing the LED
head control PCB
ASSY?
Is the problem solved
after replacing the
registration sensor
holder ASSY?
Is the problem solved
after replacing the
toner/new sensor PCB
ASSY?
3-64
Check
Result
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Remedy
Clean both electrodes.
(Refer to Fig. 3-3
(P3-32) and Fig. 3-6
(P3-33))
Clean both electrodes.
(Refer to Fig. 3-4
(P3-32) and Fig. 3-6
(P3-33))
Replace the HVPS
control PCB ASSY.
Replace the
high-voltage power
supply PCB ASSY.
Replace the engine
PCB ASSY.
Replace the main PCB
ASSY.
Replace the LED head
control PCB ASSY.
Replace the
registration sensor
holder ASSY.
Replace the toner/new
sensor PCB ASSY.
Confidential