HP 8550 Service Manual - Page 488

The copy has white vertical lines (main scanning direction) Unit Copy module Cause Step 1 Optical 2 path Original 3 exposure system Checks Make a halftone test print (TYPE=5). Does it have white bands/lines? Is the scanning lamp, reflecting plate, standard white plate, copyboard glass, or any of the mirrors soiled? Does the mount for mirror 1/2/3 move smoothly on the rail? Yes/No Action NO Go to step 2. YES Go to step 4. YES NO YES Clean the soiled part. If the dirt cannot be removed, replace the part. Remove the impediment to smooth movement. Check the cable of the original exposure system. CAUTION If you have replaced the scanner parts of the copy module (scanning lamp, mirror, CCD unit) be sure to execute CCD adjust in service mode (FUNCTION > CCD > CCD-ADJ). Further, if you have removed and replaced the scanning lamp, intensity detection PCB, standard white plate, or the CCD, be sure to execute intensity adjustment in service mode (FUNCTION > MISC-R > USE-LAMP). The copy has a specific missing color Unit Printer Cause Toner cartridge Step 1 Toner- 2 level detection Checks Remove the toner cartridge, and turn on the power. If the printer starts up normally, check each cartridge. Does it malfunction? Is the missing color black? Yes/No Action YES Replace the problem cartridge. YES No See the printer service manual. See the printer service manual. 486 Chapter 7 - Troubleshooting EN