HP 2100 Service Manual - Page 137

Repetitive Defect Ruler Repetitive print defects usually are associated with a specific roller within the printer or the Toner Cartridge. Use Figure 7-1 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 the roller in question. When the defect pattern matches the pattern of the ruler, replace the indicated roller. Figure 6-3 Repetitive Defect Ruler Half Self-Test Functional Check The electrophotographic process can be subdivided into the following stages: • Cleaning (removes excess toner from drum surface) • Conditioning (places a uniform electrical charge on drum) • Writing (laser strikes surface of drum to create latent image) • Developing (forms the toner image on drum) • Transferring (charges transfer the image to paper) • Fusing (heat and pressure produces a permanent image) The purpose of the Half Self Test Check is to determine which process is malfunctioning. Perform the test as follows: 1 Print a Configuration Page. 2 Open the top cover after the paper advances half-way through the printer (about five C4170-90959 Image Formation Troubleshooting 127