Brother Facsimile Equipment MFC7420 - Manual (Page 244)

Confidential 9-56
[ 8 ] Troubleshooting of fax functions
F-1 FAX can't send it.
User Check
(1) Verify that the telephone cord is securely inserted.
Possible cause Step Check Result Remedy
Dialing mode
setting 1 Dialing signal (PB or
DP) comes out
normally in each mode.
(Use telephone line
emulator.)
Yes Check the dialing mode setting
at customer's again.
Check the telephone line cord
between machine and socket.
Connection
between main
PCB and NCU
PCB 2 Main PCB and NCU
PCB are properly
connected. No Fix the connection properly.
Harness between
main PCB and
NCU PCB 3 Harness is damaged. Yes Replace the harness with a
normal part.
Connection
between main
PCB and control
panel PCB 4 Main PCB and control
panel PCB are properly
connected. No Fix the connection properly.
Harness between
main PCB and
control panel PCB 5 Harness is damaged. Yes Replace the harness with a
normal part.
Contact of rubber
key 6 The rubber key works
correctly. No Replace the rubber key with a
normal part.
NCU PCB 7 Replacement of NCU
PCB solves the problem. Yes Replace the NCU PCB with a
normal part.
Control panel PCB 8 Replacement of control
panel PCB solves the
problem. Yes Replace the control panel PCB
with a normal part.
Main PCB 9 Replacement of main
PCB solves the problem. Yes Replace the main PCB with a
normal part.