Canon GP335 Service Manual page 442

CHAPTER 14 TROUBLESHOOTING
3 Copy Density Auto Correction
Execute copy density auto correction for the following:
The copy image is not proper (image fault).
The laser unit has been replaced.
The image processor has been replaced.
The composite power supply PCB has been replaced.
When executing copy density auto correction, be sure to execute the following three types (five
items) as a set. Be sure to execute shading correction before executing density correction.
• Standard white paper density read
• PD density auto correction
(text, text/photo mode)
• DZ density auto correction
(photo mode)
The following blocks are subjected to correction processing:
Laser characteristic correction
Developing bias correction
Executing the Mode
a. Executing Shading Correction
1) Start service mode.
2) Select COPIER>FUNCTION>CCD in sequence; then, select <CCD-ADJ>.
3) Press the OK key. (You need not place standard white paper.)
4) End service mode; then, make two solid black copies while holding the feeder or the copyboard
glass open. Check to make sure that white lines did not occur.
14-24
FUNCTION>DENS>WHITE-ME
FUNCTION>DENS>PD-DENS
FUNCTION>DENS>PD-ME
FUNCTION>DENS>DZ-DENS
FUNCTION>DENS>DZ-ME
COPYRIGHT © 1999 CANON INC. CANON 405/335 REV.0 JAN. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)