Brother HL-600 Service Manual page 55

I-2 Dark
Possible cause Step
Contrast 1 Is the contrast adjustment dial at
failure the center click position?
Corona failure 2 Is the corona wire soiled?
(soiled wire)
Corona failure 3 Are the corona electrodes between the printer
(contact failure) body (bottom plate spring) and drum unit
soiled?
Is the bottom plate spring normal?
Is the problem solved when the drum unit is
Drum unit failure
4
replaced?
I-3 Completely blank
Possible cause Step
Developing bias 1 Are the developing bias contacts between the
contact failure printer body and drum unit soild ?
Scanner harness 2 Is the scanner LD controlharness connected
connection failure normally?
Is there any play in the connection?
Main/driver PCB 3 Are printing signals being input to the scanner?
connection failure
Check
Check
IV - 5
Result Remedy
No Set it to the center click
position or reasonable
position.
Yes Clean the corona wire.
No Clean both electrodes.
If the spring is abnormal,
replace it.
Yes Replace the drum unit with
a new one.
Result Remedy
Yes Clean the electrodes at
both sides.
Yes Connect the connector
correctly.
No Replace the main PCB or
driver PCB.