Brother HL-4140CN Service Manual page 82

■ Error code 7B
Print Unable 7B
Turn the power off and then back on again.
Engine PCB error.
Step
1 Harness connection failure
between engine PCB and main
PCB
2 Engine PCB failure
3 Main PCB failure
■ Error code 7C
Print Unable 7C
Turn the power off and then back on again.
Communication error between the engine PCB and main PCB.
This error does not usually occur in the normal use. The conceivable causes are noise around
the installation site, fluctuation of the power supply voltage, and failures in the software.
<User Check>
- Turn OFF the power switch, and turn it ON again after a while.
Step
1 Main PCB failure
■ Error code 7D
Drum Error
Slide the Green tab on Drum Unit in each color. Refer to the User's Guide for
the procedures.
Dirt on drum unit.
<User Check>
- Clean the corona wire in the drum unit.
- Replace the drum unit with a new one.
Step
1 Dirt or dust on drum unit
electrodes
2 High-voltage power supply PCB
failure
3 Engine PCB failure
4 Main PCB failure
Cause
Cause
Cause
2-51
Remedy
Check the harness connection between
the engine PCB ASSY and main PCB
ASSY, and reconnect it.
Replace the engine PCB ASSY.
Replace the main PCB ASSY.
Remedy
Replace the main PCB ASSY.
Remedy
Clean the electrodes of the drum unit and
main body. (Refer to Fig. 2-6 (next page)
and Fig. 2-9 (P2-53))
Replace the high-voltage power supply
PCB ASSY.
Replace the engine PCB ASSY.
Replace the main PCB ASSY.
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