HP 8000dn Service Manual - Page 433

Image System Troubleshooting Half Self Test Functional Check The electrophotographic process can be subdivided into the following stages: Cleaning (removing excess toner from drum surface) Conditioning (placing a uniform electrical charge on drum) Writing (laser strikes surface of drum to create latent image) Development (formation of the toner image on drum) Transfer (charge to transfer the image to paper) Fusing (heat and pressure to produce a permanent image) See Chapter 5 for more information. 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. See "Configuration Page" on page 342 for instructions. 2 Open the top cover after the paper advances half-way through the printer (about five seconds after the Main Motor begins rotating). 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), and troubleshoot the failure as a transfer or fusing problem. If NO image is present on the photosensitive drum, perform the functional checks on the following pages: EN Image Quality 409