Image Distortion - Brother HL-4040CN Service Manual

Completely blank
User Check
- Replace the toner cartridge or drum unit with a new one.
Step Cause
1 Developing bias
voltage
conduction failure
2 Scanner harness
connection failure
3 Engine PCB
failure
4 Laser unit failure
5 Transfer HVPS
PCB failure
6 Charge HVPS
PCB failure

Image distortion

Step Cause
1 Laser unit not
assembled
correctly
2 Incorrect radiation
angle of scanner
diode
Scanner motor
rotation failure
Check
Are the electrodes on the
drum unit and machine
body dirty?
Is the scanner harness
connected securely?
Is the problem solved
after replacing the engine
PCB ASSY?
Is the problem solved
after replacing the Laser
unit?
Is the problem solved
after replacing the
transfer HVPS PCB
ASSY?
Is the problem solved
after replacing the charge
HVPS PCB ASSY?
Check
Is the laser unit
assembled into the
machine securely?
(Check if there is no gap.)
Is the problem solved
after replacing the laser
unit?
1-45
Remedy
Result
Yes Clean both electrodes.
No Reconnect the scanner
harness.
Yes Replace the engine PCB
ASSY.
Yes Replace the laser unit.
Yes Replace the transfer
HVPS PCB ASSY.
Yes Replace the charge
HVPS PCB ASSY.
Remedy
Result
No Assemble the laser unit
correctly and secure the
screw.
Yes Replace the laser unit.
Confidential