HP 2100 Service Manual - Page 138

NOTE: seconds after the Main Motor begins rotation). The leading edge of the paper should have advanced past the Toner Cartridge. 3 Remove the Toner Cartridge. 4 Open the Toner Cartridge's drum shield to view the drum's surface. If a dark and distinct toner image is present on the drum's surface, assume that the first four functions of the electrophotographic process are functioning (cleaning, conditioning, writing, and developing - see Chapter 5: Functional Overview), and troubleshoot the failure as a transfer or fusing problem. If no image is present on the photosensitive drum, perform the Drum Rotation Functional Check. Drum Rotation Functional Check The photosensitive drum, located in the Toner Cartridge, must rotate for the print process to work. The photosensitive drum receives its drive from the Main Drive assembly. To verify whether the drum is rotating: 1 Open the top cover. 2 Remove the Toner Cartridge. 3 Mark the cartridge's drive gear with a felt-tipped marker. Note the position of the mark. 4 Install the Toner Cartridge and close the top cover. The start-up sequence should rotate the drum enough to move the mark. 5 Open the printer and inspect the gear that was marked in step 3. Verify that the mark moved. If the mark did not move, inspect the Main Drive assembly to ensure that it is meshing with the Toner Cartridge gears. If the drive gears function, and the drum does not move, replace the Toner Cartridge. This test is especially important if refilled Toner Cartridges are in use. 128 Chapter 6 Troubleshooting C4170-90959