HP 4550 Service Manual - Page 261

No image available Irregular, raised spots or stray toner
Toner collected on the transfer belt can cause smudging on the back of the page. Smudges commonly appear on the edges of pages after the media size is changed. The belt is selfcleaning and the smudging will normally clear within a few pages.
Toner on the edge of the media is usually caused by toner collecting on the paper guides. Inspect the paper guides and clean with a lint-free cloth if necessary.
Do not refeed paper that has already been through the printer. Re-feeding paper that has already passed through the printer can contaminate the fuser causing stray toner defects.
Paper might print with blobs after warm-up. Print a few pages to resolve the anomaly.
Verify that all media is cleared from the paper path.
The fuser roller is damaged. Replace the fuser kit.
If one toner color is streaking, that toner cartridge has been damaged. Replace the toner cartridge for the streaking color.
The paper does not meet HP paper specifications. Use media that meets HP media specifications. Light, dark, or faded print
The message TRANSFER KIT LOW REPLACE TRANSFER KIT appears on the printer control panel. Print out a configuration page to verify the remaining life of the transfer belt. Replace the transfer belt if necessary.
The moisture content of your paper is uneven or too low. Use paper from a different source or from an unopened ream of paper.
Some areas of the paper reject toner. Use paper from a different source or from an unopened ream of paper.
The paper is excessively rough. Use a smoother, xerographic paper.
The letterhead you are using is printed on rough paper. Try a smooth xerographic paper. If this solves your problem, consult with the printer of your letterhead to verify that the paper used meets the specifications for this printer.
Media does not meet the specifications for this printer. Only use media that meets the media specifications for this printer.
The printer is operating in excessively humid or dry conditions. Verify that the printing environment is within humidity specifications.
If a TONER LOW or TONER OUT message is displayed on the printer control panel, replace the appropriate toner cartridge. If the problem persists, call for service.
Excess toner may have been deposited on the transfer belt. Use a lint-free cloth to clean any excess toner from the transfer belt surface.
The laser scanner is defective.
The high-voltage power supply is defective. Light black or no black print
The black toner cartidge is empty. Replace it.
The HVPS might be faulty.
The connections into CL2 and CL3 have been switched at the clutches, not on the PCB. C7085-90921 Chapter 7 Troubleshooting 259