HP 1200 Service Manual - Page 152

Half self-test functional check The electrophotographic process can be subdivided into the following stages: ! image formation stage (charges the drum and writes a latent image to the drum with the laser) ! development stage (forms a toner image on the drum) ! transfer stage (transfers the image to paper) ! cleaning stage (removes excess toner from the drum) ! fusing stage (applies heat and pressure to make the image on paper permanent) To perform a half self-test check The purpose of the half self-test check is to determine which process is malfunctioning. 1 Print a self-test page. (See "To print a self-test page" on page 159.) 2 Open the printer door after the paper advances half-way through the printer (about five seconds after the 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 drum shield to view the drum surface. If a dark and distinct toner image is present on the drum surface, assume that the first two functions of the electrophotographic process are functioning (image formation and development). Troubleshoot the failure as a transfer or fusing problem. To perform other checks If there is no image on the photosensitive drum, perform these checks: 1 Make sure you removed the entire length of the sealing tape from the toner cartridge before you installed the cartridge. 2 Perform a drum rotation functional check. (See "Drum rotation functional check" on page 151.) 3 Perform a high-voltage power supply check. (See "High-voltage power supply check" on page 153.) 150 Chapter 6 - Troubleshooting EN