HP LaserJet M9040/M9050 Service Manual - Page 350

Drum rotation functional check The print process requires the photosensitive drum in the print cartridge to rotate. The photosensitive drum is driven from the main drive assembly. This procedure tests that it rotates: 1. Open the front cover. 2. Remove the print cartridge. 3. Mark the position of the print cartridge drive gear using a felt tip marker. 4. Reinstall the print cartridge, and close the front cover. This product startup sequence should turn the photosensitive drum enough to change the position of the drive gear. 5. Remove the print cartridge and note the position of the gear mark. If it has moved, the main drive assembly is working correctly. If it did not move, make sure that the main drive assembly is contacting the drive gear correctly. If the drive gear appear to be working correctly, replace the print cartridge. NOTE: This test is important especially when using refilled print cartridges. Calibrations The product requires calibrations after some components are replaced. The following table lists the required calibrations for each component replacement. CAUTION: Replacing these components without running the associated calibrations can cause damage to the product and can cause image quality problems. Component replaced Glass ADF width sensor ADF optical unit Flatbed optical unit Required calibration ● Leading edge glass ● Left side glass ● Leading edge front ● Left side front ● ADF plain scaling (ADF heavy scaling if necessary) ● Glass scaling ADF tray width calibration ● Leading edge back ● Left side back ● Leading edge glass ● Left side glass ● Leading edge front ● Left side front 332 Chapter 7 Solve problems ENWW