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MFC-8440/8840D/8840DN, DCP-8040/8045D/8045DN
SERVICE MANUAL
6-33
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 wire is damaged.
Yes
Replace the harness with a
normal part.
Connection
between main
PCB, relay PCB,
and control
panel PCB
5
Main PCB, relay PCB, and
control panel PCB are
properly connected.
No
Fix the connection properly.
Harness
between main
PCB, relay PCB,
and control
panel PCB
6
Harness wire 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.
Relay PCB
8
Replacement of relay PCB
solves the problem.
Yes
Replace the relay PCB with a
normal part.
Main PCB
9
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 wire 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.
Summary of Contents for DCP 8040 - B/W Laser - All-in-One
Page 272: ...CHAPTER 7 MAINTENANCE MODE 7 6 Fig 7 3 l m a b c d e f g h i j k ...
Page 343: ...APPENDIX 4 CIRCUIT DIAGRAMS A 50 Appendix 4 1 Main PCB Circuit Diagram 1 7 ...
Page 345: ...APPENDIX 4 CIRCUIT DIAGRAMS A 52 Appendix 4 3 Main PCB Circuit Diagram 3 7 ...
Page 347: ...APPENDIX 4 CIRCUIT DIAGRAMS A 54 Appendix 4 5 Main PCB Circuit Diagram 5 7 ...
Page 349: ...APPENDIX 4 CIRCUIT DIAGRAMS A 56 Appendix 4 7 Main PCB Circuit Diagram 7 7 ...
Page 351: ...APPENDIX 4 CIRCUIT DIAGRAMS A 58 Appendix 4 9 Engine PCB Circuit Diagram 1 2 ...
Page 353: ...APPENDIX 4 CIRCUIT DIAGRAMS A 60 Appendix 4 11 NCU PCB Circuit Diagram U S A ...
Page 355: ...APPENDIX 4 CIRCUIT DIAGRAMS A 62 Appendix 4 13 NCU PCB Circuit Diagram Asia ...
Page 357: ...APPENDIX 4 CIRCUIT DIAGRAMS A 64 Appendix 4 15 Control Panel PCB Circuit Diagram ...
Page 362: ...April 04 SM FAX027 1 8C5903 Printed in Japan ...