Brother 1240 Service Manual page 147

I-2 Dark
(1) Check the paper used meets the recommended paper specifications.
(2) Check the printer's environment. High temperature and high humidity conditions
can increase the amount of background shading.
(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 failure 2
Toner cartridge 3
failure
High-voltage 4
power supply
PCB failure
Main PCB failure 5
Engine PCB 6
failure
User Check
Check
Are the charge electrodes
between the printer 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 engine PCB secured
correctly?
Are there any disconnected
connectors?
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.
No Replace the engine
PCB.
6-25
CHAPTER 6 TROUBLESHOOTING
Ground
Remedy
contacts