Brother HL-1070 - B/W Laser Printer, Service Manual

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IV-8
I-4 All black
Possible cause Step Check Result Remedy
HV.GND
contacts
(Fig.4-5)
Corona failure 1 Is the corona wire of the drum
unit broken? Yes Replace the drum
unit.
2 Are the electric terminal
springs in the printer body and
the electrode on the bottom
face of the drum unit dirty? Yes Clean the terminals
in the printer and on
the drum.
➅
Harness
connection 3 Is the scanner unit connected
with the driver PCB correctly? Yes Check the harness
connection between
the scanner unit and
the driver PCB.
H.V. power
supply PCB 4 Is the problem solved after
H.V. power supply PCB
replaced? Yes Replace the H.V.
power supply PCB.
Ditto 5 Perform the same check as in
step 3. No Replace the panel
sensor PCB.
Main PCB 6 Is the problem solved after
main PCB replaced? Yes Replace the main
PCB.
Driver PCB 7 Is the problem solved after
driver PCB replaced? Yes Replace the driver
PCB.