Xerox C2424 Service Manual - Page 279

Test Print Examples (Continued) 6: Gray Fill, Dot Size Uniformity This print is made up of a 66% black fill. It reveals variations in the ink-drop-spread caused by thermal variations, transfix roller pressure variations, or drum oiling variations. Look for: Light band 1. There is a large area of differences in the density across the width of the page (a slight variation is normal). Look for a lighter vertical band, about 1/3 the width of the page, running the length of the page. Look for small, light spots, or irregular white lines, vertically aligned with each other, in the print every 125 mm (5.0 in.). Uneven fill Should see 2. Look for ink on the top and bottom margin of the page, or ink on the back of the page. This pattern is sensitive to the density variations in the paper it is printed on. Use a high-quality grade of system paper; otherwise, the print appears mottled. even fill left to right s2424-096 Causes: 1. Use the diagnostics to check the printhead and drum for correct thermal regulation. Ensure the drum fan is running properly. A vertical band, 1/3 of a page wide, running the length of the page, is caused by a stuck heating plate in the paper preheater. Run the control panel cleaning procedure Clean Print Smears, which raises the temperature of the paper preheater and may free the stuck heating plate. Additionally, you may manually force a thick sheet of paper (65 to 80 lbs.) through the paper preheater to jar the plate free. Light spots that repeat every 11.63 cm (4.58 in.) down the length of the page are caused by a defective transfix roller. The roller has a soft spot that is not pushing the ink into the paper as well as the rest of the roller. If you observe variations in the glossiness of the print, replace the maintenance kit. 2. If there is ink on the top and bottom margin of the page or ink on the back of the page, it may be caused by the roller remaining down during the print. You may hear an unusual noise if the Transfix Roller stays down and rubs against the drum. Inspect the Drive Train and ensure that it self-homes between prints. The drive train is in its home position when the two 1.5 mm holes found on the clear plastic cover align axially with corresponding holes in the gear. Another way to verify that the drive train is in its home position is to verify that the two small leaf springs from the clear plastic cover are seated correctly in their corresponding gear detent slots. Inspect the perimeter of the cam lobes for surface defects and check to see that the angular orientations of the cams match. Inspect the transfix load arm return springs. Verify that the maintenance kit returns home between prints. Inspect the cam shaft surfaces for damage. If all of these items are working correctly, replace the process drive module. 7: Manuf. Five Duplex GSF This print is used by manufacturing and engineering only. Image-Quality Troubleshooting 5-39