Brother MFC-8220 Service Manual page 212

CHAPTER 6 TROUBLESHOOTING
I-3 Completely blank
Possible cause
Developing bias
contact failure
Drum unit
Drum unit failure
Toner cartridge
failure
Scanner
harness
connection
failure
Main PCB
failure
Laser unit failure
CIS unit
User Check
(1) Check for the setting of originals.
Step
1 Are the developing bias
contacts between the machine
body and drum unit dirty?
2 Are the drum shaft and drum
electrode of the machine
connected correctly?
3 Is the problem solved after
replacing the drum unit?
4 Is the problem solved after
replacing the toner cartridge?
5 Is the scanner harness
connected securely?
(Check if there is any play in
the connection.)
6 Are printing signals being input
to the laser unit?
Is the problem solved after
replacing the main PCB?
7 Is the scanner interlock lever
damaged?
Is the scanner mirror broken or
loose?
8 Is the problem occurring on
CIS replacement?
Check Result
6-34
Remedy
Yes Clean the electrodes
at both sides.
Yes Clean the shaft and
the electrode.
No Check the connection
between the shaft and
the electrode.
Yes Replace the drum
unit.
Yes Replace the toner
cartridge with a new
one.
No Reconnect the
connector correctly.
Yes Replace the main
PCB.
Yes Replace the laser unit.
No Replace the high-
voltage power supply
PCB.
Yes Replace the CIS.
Ground
contacts
(4)
(1)
(1)