HP LaserJet 4 Service Manual - Page 271

Table 7-19 Repetitive Defects Possible Cause Action Toner Cartridge. The circumference of the photoconductive drum is 3.75 inches (94mm). The circumference of the developer roller is 2 inches (51mm). If a defect appears in the print image at these intervals, assume the defect is associated with the Toner Cartridge. Replace the Toner Cartridge. Fuser Assembly. The Fuser Roller's circumference is approximately 2.5 inches (63mm) for the LJ4, and 3-1/8 (79mm) for the LJ4+/5. If a defect appears at this interval, assume the defect is associated with the Fuser Assembly. Clean the Fuser Assembly rollers. Replace the assembly if necessary. Dirty Roller. Any dirty roller along the paper path may result in a pattern of repetitive print image defects. Examine and clean rollers along the paper path. For further information on interval dimensions, refer to the Repetitive Defect Ruler, Figure 7-19. Troubleshooting 7-41