Brother International MFC-7050C Service Manual - Page 122

inoperative.

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2.4 Troubleshooting Procedures [ 1 ] Control panel related Trouble (1) LCD shows nothing. (2) Control panel inoperative. Check: • Panel-main harness • Control panel PCB • Power supply PCB • Main PCB • Interface PCB • Power supply harnesses (1 and 2), connecting the interface PCB and main PCB with each other • Panel-main harness • Control panel PCB • FPC key • Main PCB [ 2 ] Telephone related Trouble (1) No phone call can be made. (2) Speed dialing or one-touch dialing will not work. (3) Speaker silent during onhook dialing. (4) Telephone does not ring. Check: • FPC key • Hook switch PCB • Control panel PCB • NCU PCB • Main PCB • NCU harness • 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. • Ordinary dialing function (Pick up the handset and press the numerical keys.) If it works normally, proceed to the following checks; if not, refer to item (1) above. • Speaker • Speaker • NCU PCB • Main PCB • NCU harness VI - 5

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2.4
Troubleshooting
Procedures
[
1
]
Control
panel
related
Trouble
Check:
(1)
LCD
shows
nothing.
•
Panel
-main
harness
•
Control
panel
PCB
•
Power
supply
PCB
•
Main
PCB
•
Interface
PCB
•
Power
supply
harnesses
(1
and
2),
connecting
the
interface
PCB
and
main
PCB
with
each
other
(2)
Control
panel
inoperative.
•
Panel
-main
harness
•
Control
panel
PCB
•
FPC
key
•
Main
PCB
[
2
]
Telephone
related
Trouble
Check:
(1)
No
phone
call
can
be
made.
•
FPC
key
•
Hook
switch
PCB
•
Control
panel
PCB
•
NCU
PCB
•
Main
PCB
•
NCU
harness
(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
(Pick
up
the
handset
and
press
the
numerical
keys.)
If
it
works
normally,
proceed
to
the
following
checks;
if
not,
refer
to
item
(1)
above.
•
Speaker
(4)
Telephone
does
not
ring.
•
Speaker
•
NCU
PCB
•
Main
PCB
•
NCU
harness
VI
-
5