HP 8550 Service Manual - Page 465

Note Check the intermediate transfer drum unit, fusing assembly, intermediate transfer drum cleaning roller, secondary transfer belt assembly, toner cartridge, and drum cartridge to make sure that they are properly mounted. Paper Media should meet the specifications outlined by HP. See the media guidelines on page "Supported media" on page 29. Also check the HP Media Specifications Guide. Environmental factors can affect media; try some new media, fresh from its packaging. Placement of copy paper Copy paper must be placed in the cassette or the multi-feeder tray in an appropriate volume and in the correct orientation. Transparencies must be placed on the multi-feeder tray with the correct orientation. Condensation In the winter, bringing a copier from a cold place to a warm one can cause condensation inside the printer, leading to various problems. l Condensation in the original exposure system or the drum exposure system (six-facet mirror, reflecting mirror, lens) can produce light images. l Condensation in the charging system can cause leakage. l Condensation on the pick-up/feeding guide can cause feeding faults. l When cold, the photo-conducting layer of the photosensitive drum inside the drum cartridge tends to have a high resistance, causing poor contrast on copies. l Condensation on the surface of the intermediate transfer drum can cause ITD cleaning faults. If condensation is found, wipe the parts dry, or leave the copier turned on for 10 to 20 minutes. Opening a toner cartridge immediately after bringing it in from a cold place will also cause condensation. Instruct the user to make sure that the cartridges have reached room temperature by leaving them in the room where they will be used for one to two hours before opening them. If uneven density (difference in density between front and rear), light image, or fogging is noted, execute auto gradation correction in user mode. EN Copy module troubleshooting 463