HP 4550 Service Manual - Page 245

Image formation troubleshooting The image formation system (Figure 7-6) consists of the following imaging units:
photosensitive drum cartridge carousel
laser/scanner
toner cartridges
intermediate transfer belt (ITB) unit
secondary transfer roller Figure 7-6 Image formation Before beginning image formation troubleshooting, check that the media meets the specifications listed in the HP LaserJet Printer Family Print Media Guide. Print density test and color checks Use the configuration page to check the print density of the black, primary, and process color levels. Solid black and color-filled areas on the configuration page demonstrate the ability to print at full density. To print a configuration page, see page 287. In addition to the items listed above, the configuration page provides the following information:
It helps isolate the problem to the software or the printer.
It shows that all colors print. The following media-related items are responsible for many image formation and print-quality defects:
rough paper
heavy paper
transparencies out of the specified thickness range
paper that has absorbed too much moisture from the atmosphere
room environment (humidity too high or low) C7085-90921 Chapter 7 Troubleshooting 243