Brother MFC6800 - Troubleshooting Procedures; 1 ] Control Panel Related; 2 ] Telephone Related

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6.2.4 Troubleshooting Procedures
[ 1 ] Control panel related
Trouble Check:
(1) LCD shows nothing.
 Panel harness between the control panel PCB and relay
PCB
 Relay (CCD/PANEL) harness between the relay PCB
and main PCB
 Control panel PCB
 Low-voltage power supply PCB
 Main PCB
 LCD
(2) Control panel inoperative.
 Panel harness between the control panel PCB and relay
PCB
 Relay (CCD/PANEL) harness between the relay PCB
and main PCB
 Control panel PCB
 FPC key
 Main PCB
[ 2 ] Telephone related
Trouble Check:
(1) No phone call can be made.
 FPC key
 Control panel PCB
 NCU PCB
 Main PCB
(2) Speed dialing or one-touch dialing
will not work.
 Ordinary dialing function (other than the speed and
one-touch dialing)
If it works normally, check the main PCB; if not, refer
to item (1) above.
(3) Speaker silent during on-hook
dialing.
 Ordinary dialing function (other than the on-hook
dialing with the hook key)
If it works normally, proceed to the following checks; if
not, refer to item (1) above.
(4) Dial does not switch between tone
and pulse.
 Main PCB
 NCU PCB
(5) Telephone does not ring.
 Speaker
 NCU PCB
 Main PCB