HP 4300 Service Manual - Page 345

CAUTION Note Repetitive defects troubleshooting Defects on printer rollers can cause image defects to appear at regular intervals on the page. These defects appear at regular intervals that correspond to the circumference of the roller causing the defect. Measure the distance between defects that recur on a page. Use table 75 or the repetitive defect ruler (figure 207) to determine which roller is causing the defect. To resolve the problem, try cleaning the roller first. If the roller is still dirty after cleaning or if it is damaged, replace the indicated part. Do not use solvents or oils to clean rollers. Instead, rub the roller with lint-free paper. If dirt is difficult to remove, rub the roller with lint-free paper dampened with water. Table 75. Repetitive defects Roller Distance between defects Replacement part Primary charging roller 37.7 mm (1.5 inches) print cartridge Developer roller* 62.8 mm (2.5 inches) print cartridge Fuser 75.0 mm (2.95 inches; HP LaserJet 4200) 94.0 mm (3.75 inches; HP LaserJet 4300) Fuser Photosensitive drum 94.2 mm (3.75 inches) print cartridge *The developer roller circumference is 62.8 mm (2.5 inches). This defect will most likely repeat at intervals of 54.0 mm (2.125 inches) because of the way it is geared. Defects on the tray pickup rollers or the tray 1 pickup roller do not cause a repetitive defect. Defects on these rollers cause a defect to appear only on the leading edge of the image. First occurrence of the defect 37.7 mm (1.5 inches) primary charging roller *Note: The developer roller circumference is 62.83 mm (2.5 inches). This defect will most likely repeat at intervals of 54.0 mm (2.15 inches) because of the way it is geared. 54.0 mm (2.125 inches) developer roller (see note)* 62.8 mm (2.5 inches) developer roller (see note)* 75.0 mm (2.95 inches) fuser (HP LaserJet 4200) Figure 207. 94.0 mm (3.75 inches) fuser (HP LaserJet 4300) 94.2 mm (3.75 inches) photosensitive drum Repetitive defect ruler Q2431-90912 Chapter 7 Troubleshooting 325