HP 2700n Service Manual - Page 234

Repetitive-defects troubleshooting Defects on printer rollers can cause image defects to appear at regular intervals on the page. Use Table 6-26 Causes of repetitive defects on page 216 to determine which roller is causing the defect. To resolve the problem, try cleaning the roller. If the roller remains dirty after cleaning or if it is damaged, replace it. Repetitive defects for the transfer unit normally appear on every other page, because the transfer belt is longer than a page. However, the period of the repetitive defect can vary depending on the type of media, and a repetitive defect can occur more than once on the same page. CAUTION Do not use solvents or oils to clean rollers. Instead, use lint-free paper to clean the roller. If dirt is difficult to remove, dampen the paper with rubbing alcohol. NOTE Defects on the tray 2 pickup roller or the multipurpose-tray pickup roller do not cause a repetitive defect, but instead cause a defect on the leading edge of the page. Table 6-26 Causes of repetitive defects Problem Area Primary charging roller Developing cylinder Registration roller (inside) Registration roller (outside) Transfer roller Fuser sleeve Photosensitive drum Fuser pressure roller Period of defect (mm) About 27 About 27 About 35 About 36 About 44 About 75 About 76 About 79 Problem Dirt on front X X X Blank spots X X X X X X X X Dirt on back Poor fuser X X X X X Repetitive print defects are usually caused by a specific roller, cylinder, or drum in the printer or the print cartridge. Use the following figure to isolate the cause of repetitive print defects. Align the first occurrence of the defect with the top of the "ruler" (at the top or bottom of the misprinted page), and measure to the next occurrence of the defect to determine which roller, cylinder, or drum is causing the defect. When the defect pattern matches the pattern of the ruler, replace the indicated part. 216 Chapter 6 Troubleshooting ENWW