Brother MFC-7450

1-56
Confidential
■ Speaker is silent during on-hook dialing.
■ Dialing function does not switch between "tone" and "pulse".
Step Cause Check Result Remedy
1
Connection
between main
PCB and
speaker
Are the main PCB and
speaker connected
correctly?
No
Reconnect the connector.
2
Speaker Is the problem solved
after replacing the
speaker?
Ye s
Replace the Speaker.
3
Connection
between main
PCB and NCU
PCB
Are the main PCB and
NCU PCB connected
correctly?
No
Reconnect the connector.
4
Connection
between main
PCB and control
panel PCB
Are the main PCB and
control panel PCB
connected correctly?
No
Reconnect the connector.
5
NCU PCB Is the problem solved
after replacing the NCU
PCB ASSY?
Ye s
Replace the NCU PCB
ASSY.
6
Main PCB Is the problem solved
after replacing the main
PCB ASSY?
Ye s
Replace the main PCB
ASSY.
Step Cause Check
Result Remedy
1
Connection
between main
PCB and NCU
PCB
Are the main PCB and
NCU PCB connected
correctly?
No
Reconnect the connector.
2
NCU PCB Is the problem solved
after replacing the NCU
PCB ASSY?
Ye s
Replace the NCU PCB
ASSY.
3
Main PCB Is the problem solved
after replacing the main
PCB ASSY?
Ye s
Replace the main PCB
ASSY.