Brother HL-4140CN Service Manual page 79

■ Error code 71
Print Unable 71
Turn the power off and then back on again.
Laser unit polygon motor error.
Error code 72
Print Unable 72
Turn the power off and then back on again.
Beam detecting sensor (Black/Yellow) error of the laser unit.
Error code 73
Print Unable 73
Turn the power off and then back on again.
Beam detecting sensor (Cyan/Magenta) error of the laser unit.
<User Check>
- Open the front and back covers and leave them for 30 minutes or more with the power ON.
After that, close the front and back covers and turn OFF and ON the power switch.
Step
1 Harness connection failure of
laser unit
2 Laser unit failure
3 Engine PCB failure
4 Main PCB failure
Cause
2-48
Remedy
Check the harness connections (at three
locations) of the laser unit and reconnect
them.
Replace the laser unit.
Replace the engine PCB ASSY.
Replace the main PCB ASSY.
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