HP 8550 Service Manual - Page 487

The copy has vertical lines (main scanning direction) Unit Copy module Cause Step 1 Optical 2 path Power 3 supply voltage, scanning lamp, inverter PCB Original 4 exposure system CCD unit 5 Checks Yes/ No Make a halftone test print NO (TYPE=5). Does it have horizontal YES bands or lines? Is the scanning lamp, reflecting plate, standard white plate, copyboard glass, or any of the mirrors soiled? YES Does the scanning lamp flicker? YES Does the mount for mirror 1/2/3 NO move smoothly on the rail? Remove the CCD cover, and clean YES the surface of the CCD with a NO blower brush. Is the problem corrected? Action Go to step 2. Go to step 6. Clean the soiled part. If the dirt cannot be removed, replace the part. 1. Check for fluctuation in the power supply voltage. 2. Check the scanning lamp and the inverter PCB; if faulty, replace the part. Remove the impediment to smooth movement. End. Replace the CCD unit. EN Copy module troubleshooting 485