Troubleshooting By Symptom - Canon MP640 Service Manual

2-3. Troubleshooting by Symptom

Faulty operation
Unsatisfactory print quality No printing, or no color ejected.
Symptom
The power does not turn on.
The power turns off immediately
after power-on.
A strange noise occurs.
The LCD does not display properly.
A portion of the LCD is not
displayed.
The display flickers.
Paper feed problems (multi-feeding,
skewed feeding, no feeding).
Faulty scanning (no scanning,
strange noise).
The CD / DVD tray is not pulled in
the feeder.
Faint printing, or white lines on
printouts.
Uneven printing.
Improper color hue.
Paper gets smeared.
(1) Confirm connection of the power supply unit:
- Harness and connector conditions
(2) Replace the following item(s):
- Logic board
- Power supply unit
- Panel board
(1) Examine and remove any foreign material or paper debris.
(2) Replace the following item(s):
- The part generating the strange noise
- Logic board
(1) Confirm cable connection (LCD FFC and panel harness):
- Harness and connector conditions
- No cable breakage, etc.
(2) Replace the following item(s):
- LCD FFC
- LCD viewer unit
- Panel board
- Logic board
(1) Examine and remove any foreign material or paper debris.
(2) Confirm that the paper guides are set properly.
(3) Confirm the PF rear cover and the cassette conditions.
(4) Confirm cable connection.
(5) Replace the following item(s):
- ASF unit (for paper feeding error from the rear tray)
- PF pick-up unit (for paper feeding error from the cassette)
- PE sensor board
- Pressure roller unit
- Cassette unit
(1) Confirm cable connection (scanner motor cable and CIS
FFC):
- Harness and connector conditions
- No cable breakage, etc.
(2) Replace the following item(s):
- Scanner unit
- Logic board
(1) Confirm the reflector of the back of the CD / DVD tray:
- Cleaning of the reflector
(2) Replace the following item(s):
- Logic board
- CD-R tray
- Platen unit
(1) Confirm the ink tank conditions:
- Confirmation of the air-through of an ink tank
- Re-setting of an ink tank
- Whether the ink tank is Canon-genuine one or not
- Whether the ink tank is refilled one or not
(2) Remove foreign material from the purge unit caps, if any.
(3) Perform cleaning or deep cleaning of the print head.
(4) Perform print head alignment.
(5) Replace the following item(s):
*1
- Print head , and ink tanks
- Logic board
- Purge drive system unit
(1) Clean the inside of the machine.
(2) Perform bottom plate cleaning.
14 / 54
Solution