HL-5240/5250DN/5270DN/5280DW SERVICE MANUAL
Confidential
4-41
(I-3) Completely blank
Possible cause
Step
Check
Result
Remedy
Ground
contacts
Developing bias
contact failure
1
Are the developing bias
contacts between the printer
body and drum unit dirty?
Yes
Clean the electrodes
at both sides.
Yes
Clean the shaft and
the electrode.
Drum unit
2
Are the drum shaft and drum
electrode of the printer body
connected correctly?
No
Check the connection
between the shaft and
the electrode.
Drum unit failure
3
Is the problem solved after
replacing the drum unit?
Yes
Replace the drum
unit.
Toner cartridge
failure
4
Is the problem solved after
replacing the toner cartridge?
Yes
Replace the toner
cartridge with a new
one.
Scanner
harness
connection
failure
5
Is the scanner harness
connected securely?
(Check if there is any play in
the connection.)
No Reconnect
the
connector correctly.
Main PCB
failure
6
Are printing signals being input
to the laser unit?
Is the problem solved after
replacing the main PCB?
Yes
Replace the main
PCB.
Yes
Replace the laser unit.
Laser unit failure
7
Is the scanner interlock lever
damaged?
Is the scanner mirror broken or
loose?
No
Replace the high-
voltage power supply
PCB.