CHAPTER 10 TROUBLESHOOTINGCOPYRIGHT © 1999 CANON INC. CANON NP6320 REV.0 DEC. 1999 PRINTED IN JAPAN (IMPRIME AU JAPON)10-282. Light image (even in dark areas)3. Light image (very light overall)Cause ActionEnd.Perform step 6 and subse-quent steps.1. Install the corona wirescorrectly.2. Adjust the height of thecorona wires.3. Clean the corona wire.4. Install the corona assem-bly securely.1. The paper may have ab-sorbed moisture, so in-struct the user about thecorrect method of storingpaper.2. Explain to the user that ifpaper not recommendedby Canon is being used,the image quality maynot be as expected.1. Check if the lower trans-fer assembly guide plateis touching the spring ofthe feeder.2. Replace the varistor.Check the high-voltagetransformer and the DCcontroller PCB.Check the pressure apply-ing mechanism of the de-veloping assembly.If the problem is in theblack developing assembly,see sub-section "Add Tonerindicator does not go ON."Check if the developingbias is being supplied to thedeveloping cylinder.YES/NOYESNONOYESYESNONONOYESChecksDoes the image quality improve after the BasicAdjustment Procedure is followed?Switch the copier OFF during copying andopen the front door. Does the toner image onthe surface of the photosensitive drum (prior totransfer) appear normal?Are the corona and grid wires of the transfercorona assembly installed correctly, and is thecorona wire height normal?Does the image become darker when freshcopy paper is used?Is the resistance between the metal part of thelower transfer guide and the feeder 0Ω?Is the developing roller of the developing as-sembly pressing against the photosensitivedrum?Is the surface of the developing cylinder coateduniformly with toner?Developing defect Faulty transferTransfer coronaassemblyCopy paper• Lower transferassemblyguide plate• Varistor• High-voltagetransformer• DC controlerPCBDeveloping unitpressure apply-ing mechanismAmount of tonerin developingassemblyDeveloping biasStep1234567
