Brother DCP-9040CN Service Manual page 38

Error code 71
Print Unable 71
Turn the power off and then back on again.
Polygon motor failure
Error code 72
Print Unable 72
Turn the power off and then back on again.
Beam detecting sensor (K) failure
Error code 73
Print Unable 73
Turn the power off and then back on again.
Beam detecting sensor (C) failure
Step
1 Condensation on laser unit
2 Laser unit harness connection
failure
3 Laser unit failure
4 Engine PCB failure
Cause
Turn the power off and leave the machine in an
airy place at normal room temperature.
Check the two harness connections of the laser
unit and reconnect them.
Replace the laser unit.
Replace the engine PCB ASSY.
1-19
Remedy
Confidential