Brother Facsimile Equipment MFC7420 - Manual (Page 247)

Confidential 9-59
F-5 Speaker is silent during on-hook dialing.
Possible cause Step Check Result Remedy
Connection
between main
PCB and speaker 1 Main PCB and speaker
are properly connected. No Fix the connection properly.
Speaker 2 Replacement of speaker
solves the problem. Yes Replace the speaker with a
normal part.
Connection
between main
PCB and NCU
PCB 3 Main PCB and NCU
PCB are properly
connected. No Fix the connection properly.
Harness between
main PCB and
NCU PCB 4 Harness is damaged. Yes Replace the harness with a
normal part.
Connection
between main
PCB and control
panel PCB 5 Main PCB and control
panel PCB are properly
connected. No Fix the connection properly.
Harness between
main PCB and
control panel PCB 6 Harness is damaged. Yes Replace the harness with a
normal part.
NCU PCB 7 Replacement of NCU
PCB solves the
problem. Yes Replace the NCU PCB with a
normal part.
Main PCB 8 Replacement of main
PCB solves the
problem. Yes Replace the main PCB with a
normal part.
F-6 Dialing function does not switch between "tone" and "pulse".
Possible cause Step Check Result Remedy
Connection
between main
PCB and NCU
PCB 1 Main PCB and NCU
PCB are properly
connected. No Fix the connection properly.
Harness between
main PCB and
NCU PCB 2 Harness is damaged. Yes Replace the harness with a
normal part.
NCU PCB 3 Replacement of NCU
PCB solves the
problem. Yes Replace the NCU PCB with a
normal part.
Main PCB 4 Replacement of main
PCB solves the
problem. Yes Replace the main PCB with a
normal part