Brother HL-4040CN, HL-4050CDN, HL-4070CDW Service Manual page 34

Error code 3D
Print Unable 3D
Turn the power off and then back on again.
Main PCB failure (Any of the PCBs is judged to be failure by the PCB checker, or it is not tested
with the checker.)
Step
1 Main PCB failure
2 Engine PCB failure
Error code 3F
Print Unable 3F
Turn the power off and then back on again.
Writing error into engine firmware
Step
1 The machine is turned off
while rewriting the data into
the engine firmware.
Error code 56
Cover is Open
Close the Back Cover.
Back cover opened
User Check
- Check if the back cover is closed certainly.
Step
1 Back cover switch failure
2 Harness connection failure of
back cover switch ASSY
3 Part pressing the back cover
switch is broken, which is
provided at the right side of
back cover inside.
4 Engine PCB failure
Cause
Replace the main PCB ASSY.
Replace the engine PCB ASSY.
Cause
Turn the power on. Resend the engine firmware
(DJF format) with the USB memory while the error
code is being indicated.
Cause
Check the sensor performance following the
procedure described in
Check the harness connection of the back cover
switch ASSY and reconnect it.
Replace the back cover switch ASSY.
Replace the engine PCB ASSY.
1-17
Remedy
Remedy
Remedy
"Maintenance mode
Confidential
32".