Troubleshooting By Symptom - Canon MP638 Service Manual

2-5. 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.
The back side of 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 FCC 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 the PF rear cover and the cassette conditions.
(3) Confirm cable connection.
(4) 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 / DVD tray
(1) Confirm the ink tank conditions:
- Confirmation of the air-through of an ink tank (proper
removal of the orange tape)
- Re-setting of an ink tank
(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.
(3) Perform paper feed roller cleaning.
(1) Clean the inside of the machine.
(2) Perform cleaning or deep cleaning of the print head.
(3) Examine the platen ink absorber.
(4) Examine the paper eject roller.
(5) Replace the following item(s):
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Solution