Troubleshooting For Control Panel Problems; Leds Are Not Activated; Control Panel Is Inoperable - Brother HL-5440D Service Manual

4.6

Troubleshooting for Control Panel Problems

4.6.1 Nothing is displayed on the LCD
Step
1 AC cord failure
Connection failure of the panel
2
harness
Connection failure of the backlight
3
harness
Connection failure of the LCD
4
harness
5 LCD failure
6 Backlight PCB failure
7 Panel PCB failure
Low-voltage power supply PCB
8
failure
9 Main PCB failure

4.6.2 LEDs are not activated

Step
1 AC cord failure
Connection failure of the panel
2
harness
3 Panel PCB failure
Low-voltage power supply PCB
4
failure
5 Main PCB failure

4.6.3 Control panel is inoperable

<User Check>
- Check that the function lock is not set.
Step
1 Panel unit attachment failure
Connection failure of the panel
2
harness
3 Rubber key failure
4 Panel PCB failure
Low-voltage power supply PCB
5
failure
6 Main PCB failure
Cause
Replace the AC cord.
Check the connection of the panel harness,
and reconnect it if necessary.
Check the connection of the backlight
harness, and reconnect it if necessary.
Check the connection of the LCD harness,
and reconnect it if necessary.
Replace the LCD.
Replace the backlight PCB ASSY.
Replace the panel PCB ASSY.
Replace the low-voltage power supply PCB
ASSY.
Replace the main PCB ASSY.
Cause
Replace the AC cord.
Check the connection of the panel harness,
and reconnect it if necessary.
Replace the panel PCB ASSY.
Replace the low-voltage power supply PCB
ASSY.
Replace the main PCB ASSY.
Cause
Reattach the panel unit.
Check the connection of the panel harness,
and reconnect it if necessary.
Replace the rubber key printed ASSY.
Replace the panel PCB ASSY.
Replace the low-voltage power supply PCB
ASSY.
Replace the main PCB ASSY.
2-75
Remedy
Remedy
Remedy
Confidential