HP 8550 Service Manual - Page 485

The copy has vertical lines (sub-scanning direction) Unit Copy module Printer Cause Step 1 Optical 2 path 3 Photo- 4 sensitive drum Upper 5 fusing roller Checks Yes/ No Make a halftone test print (TYPE=5). Does it have vertical bands or lines? NO YES Is the scanning lamp, reflecting plate, standard white plate, copyboard glass, or any of the mirrors soiled? YES Remove the CCD cover, and clean YES the surface of the CCD with a NO blower brush. Is the problem corrected? Are there scratches in the peripheral direction (sub-scanning direction) of the photosensitive drum? YES Are there scratches in the YES peripheral direction (sub-scanning direction) of the upper fusing roller? Action Go to step 2. Go to step 4. Clean the soiled part. If the dirt cannot be removed, replace the part. End. Replace the CCD unit. Replace the photosensitive drum cartridge. Replace the upper fusing roller. EN Copy module troubleshooting 483