Brother International MFC 8890DW Service Manual - Page 144

Speaker is silent during on-hook dialing., Dialing function does not switch between tone and

Page 144 highlights

■ Speaker is silent during on-hook dialing. Step 1 2 3 4 5 6 Possible cause Connection between main PCB and speaker Speaker Connection between main PCB and NCU PCB Harness between main PCB and NCU PCB Connection between main PCB and control panel PCB Harness between main PCB and control panel PCB Check Are the main PCB and speaker connected properly? Is the problem solved after replacing the speaker? Are the main PCB and NCU PCB connected properly? Is the harness damaged? Are the main PCB and control panel PCB connected properly? Is the harness damaged? Result Remedy Reconnect the connector No properly. Replace the Speaker. Yes Reconnect the connector No properly. Replace the harness with a Yes normal one. Reconnect the connector No properly. Replace the harness with a Yes normal one. NCU PCB 7 Main PCB 8 Is the problem solved after replacing the NCU PCB ASSY? Is the problem solved after replacing the main PCB ASSY? Replace the NCU PCB Yes ASSY. Replace the main PCB Yes ASSY. ■ Dialing function does not switch between "tone" and "pulse". Step 1 2 3 4 Possible cause Connection between main PCB and NCU PCB Harness between main PCB and NCU PCB NCU PCB Main PCB Check Are the main PCB and NCU PCB connected properly? Result Remedy Reconnect the connector No properly. Is the harness damaged? Replace the harness with a Yes normal one. Is the problem solved after replacing the NCU PCB ASSY? Is the problem solved after replacing the main PCB ASSY? Replace the NCU PCB Yes ASSY. Replace the main PCB Yes ASSY. 3-72 Confidential

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3-72
Confidential
Speaker is silent during on-hook dialing.
Dialing function does not switch between "tone" and "pulse".
Step
Possible cause
Check
Result
Remedy
1
Connection
between main
PCB and
speaker
Are the main PCB and
speaker connected
properly?
No
Reconnect the connector
properly.
2
Speaker
Is the problem solved
after replacing the
speaker?
Yes
Replace the Speaker.
3
Connection
between main
PCB and NCU
PCB
Are the main PCB and
NCU PCB connected
properly?
No
Reconnect the connector
properly.
4
Harness
between main
PCB and NCU
PCB
Is the harness
damaged?
Yes
Replace the harness with a
normal one.
5
Connection
between main
PCB and control
panel PCB
Are the main PCB and
control panel PCB
connected properly?
No
Reconnect the connector
properly.
6
Harness
between main
PCB and control
panel PCB
Is the harness
damaged?
Yes
Replace the harness with a
normal one.
7
NCU PCB
Is the problem solved
after replacing the NCU
PCB ASSY?
Yes
Replace the NCU PCB
ASSY.
8
Main PCB
Is the problem solved
after replacing the main
PCB ASSY?
Yes
Replace the main PCB
ASSY.
Step
Possible cause
Check
Result
Remedy
1
Connection
between main
PCB and NCU
PCB
Are the main PCB and
NCU PCB connected
properly?
No
Reconnect the connector
properly.
2
Harness
between main
PCB and NCU
PCB
Is the harness
damaged?
Yes
Replace the harness with a
normal one.
3
NCU PCB
Is the problem solved
after replacing the NCU
PCB ASSY?
Yes
Replace the NCU PCB
ASSY.
4
Main PCB
Is the problem solved
after replacing the main
PCB ASSY?
Yes
Replace the main PCB
ASSY.