Troubleshooting Based On Problem Type; 1 ] Control Panel Problems; 2 ] Telephone Problems - Brother MFC640CW Service Manual

9.2.4 Troubleshooting based on problem type

[ 1 ] Control panel problems

Problem
(1) LCD shows nothing.
(2) Control panel inoperative.
(3) Center panel inoperative.
(MFC820CW)

[ 2 ] Telephone problems

Problem
(1) No phone call can be made.
(2) Speed dialing will not work.
(3) Dial does not switch between
tone and pulse.
(4) Telephone does not ring.
• Panel-main harness (MFC640CW/DCP340CW)
• LCD flat cable or color LCD (MFC820CW)
• Control panel PCB (MFC640CW/DCP340CW)
• Power supply PCB
• Main PCB
• Panel-main harness (MFC640CW/DCP340CW)
• Panel-center panel harness or center panel-main harness
(MFC820CW)
• Control panel PCB
• Center panel PCB (MFC820CW)
• Rubber keypad
• Main PCB
• Panel-center panel harness or center panel-main harness
(MFC820CW)
• Center panel PCB
• Main PCB
• Rubber keypad
• Control panel PCB
• Main PCB
• MJ PCB
• 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.
• Main PCB
• Speaker
• Main PCB
• MJ PCB
9 - 2 8
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