Canon PC980 Service Manual - Page 319

CHAPTER 11 TROUBLESHOOTING 4 The copy has uneven density. (darker at front) 5 The copy has uneven density. (lighter at front) Cause Scanner Cartridge, Scanning lamp Transfer charging roller Step 1 2 Checks Clean the scanning lamp, reflecting plate, lens, and mirror. Is the problem corrected? Turn off the power in the middle of a copying run, and open the machine. Is the toner image on the photosensitive drum before transfer more or less uneven? YES/NO Action YES End. YES 1. Replace the cartridge. 2. Replace the scanning lamp. NO 1. Mount the transfer charging roller correctly. 2. Replace the transfer charging roller correctly. 6 The copy is foggy. (entire face) Cause Scanner Grounding spring Scanning lamp, Developing bias Step 1 2 3 Checks Is the density correction switch (SW101) or the density adjusting lever set to the middle setting? Clean the scanning lamp, reflecting plate, lens, and mirror. Is the problem corrected? Set the cartridge in the machine. Is there electrical continuity between the PCB of the base of the drum and the machine's top unit? YES/NO NO YES NO YES Action Set the switch or the lever to the middle setting, and make a copy. If the image is still foggy, to step 2). End. Check to see if the grounding spring is mounted correctly (in reference to the drum drive gear). 1. Check the activation of the scanning lamp. 2. Check the developing assembly. 11-54 COPYRIGHT © 1999 CANON INC. CANON PC800s/900s REV.0 AUG. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)