HP Color LaserJet 8500 Service Manual - Page 456

Note Charge roller set (See figure 228 on page 447 for an example of this print defect.) Charge roller set print defect, usually only noticeable in lighter halftone colors, is characterized by banding lines at intervals of 44 mm (approximately 1.75 inches). The print defect usually appears immediately after installing a new imaging drum or if the printer has been in storage without power applied for a prolonged period of time. The conductive rubber charge roller inside the imaging drum cartridge can flatten on one side when the drum sits idle. A charge roller typically returns to a cylindrical shape within 24 hours after installation or after printing approximately 100 pages, so the image defect diminishes with use or time. Do not replace the new imaging drum with another new imaging drum. Doing so can cause the image defect to appear worse. Instead, wait 24 hours or print 100 sheets of a medium-coverage print job. Waves (See figure 229 on page 448 for an example of this print defect.) Waves are characterized by color printing that appears "choppy" in transition from high-coverage to low-coverage areas of the printed page. Waves can appear late in the life of a color toner cartridge, especially when the cartridge has seen prolonged use at very low coverage; there might still be toner in the cartridge, but it might be "worn out." Solve the print defect by replacing the color toner cartridge. For example, if waves appear in magenta or colors that use magenta (reds and blues), replace the magenta cartridge. Missing toner (See figure 230 on page 449 for an example of this print defect.) The "missing toner" print defect is characterized by small speckles, caused by missing toner, that appear usually in lighter colors within two or three centimeters (approximately one inch) of the leading or trailing edge. To avoid the print defect, use better quality or heavier media. Also try using darker colors and avoiding light colors in these areas. 454 Chapter 7 - Troubleshooting EN