![background image](http://html.mh-extra.com/html/canon/canoscan-n1220u/canoscan-n1220u_service-manual_62826070.webp)
CHAPTER 5
5 - 2
COPYRIGHT
2000 CANON INC. CANOSCAN N650U/N656U/N1220U REV.0 JUNE 2000 PRINTED IN JAPAN (IMPRIME AU JAPON)
II. TROUBLESHOOTING
Causes and corrective actions for possible image defects and malfunctions during operation
are described below.
A. Troubleshooting Image Defects
1. Image not output
Cause 1
: Faulty connection of the USB cable
Corrective action : Securely connect the USB cable.
Cause 2
: Faulty contact image sensor
Corrective action : Replace the contact image sensor.
Cause 3
: Faulty main PCB
Corrective action : Replace the drive unit.
2. Uneven image density or lines
Cause 1
: Dirt on the document cover or document glass
Corrective action : Clean the document cover or document glass.
Cause 2
: Faulty calibration data
Corrective action : Perform the calibration.
Cause 3
: External light is entering into the scanner. External light entering into
the contact image sensor can cause uneven image density.
Corrective action : Fully close the document cover. If it is impossible, cover with a sheet
etc. to prevent external light.
Cause 4
: Faulty contact image sensor
Corrective action : Replace the contact image sensor.
Cause 5
: Faulty main PCB
Corrective action : Replace the drive unit.