Brother MFC-8460N Servise Manual page 353

(I-2) Dark
(1) Check the paper used meets the recommended paper specifications.
(2) Check the machine's environment. High temperature and high humidity
(3) Clean the corona wire with the wire cleaner.
(4) Try installing a new toner cartridge or drum unit.
Possible cause
Step
Corona failure 1
(contact
failure)
Drum unit 2
failure
Toner 3
cartridge
failure
High-voltage 4
power supply
PCB failure
Main PCB 5
failure
User Check
conditions can increase the amount of background shading.
Check
Are the charge electrodes
between the machine body
and the drum unit dirty?
Is the problem solved after
replacing the drum unit?
Is the problem solved after
replacing the toner
cartridge?
Is the connections of the
connector between the
high-voltage power supply
PCB and the main PCB
secured correctly?
Are there any disconnected
connectors?
Result
Yes Clean both electrodes.
Yes Replace the drum unit
with a new one.
Yes Replace the toner
cartridge with a new
one.
Yes Replace the high-
voltage power supply
PCB.
No Replace the main PCB.
9-29
Ground
Remedy
contacts
(3)
Confidential