HP Color LaserJet Enterprise CM4540 Service Manual - Page 666

Solve image-quality problems This section helps you define print-quality problems and what to do to correct them. Often print-quality problems can be handled easily by making sure that the product is maintained, using paper that meets HP specifications, or running a cleaning page. Print quality examples The following examples depict letter-size paper that has passed through the product short-edge first. These examples illustrate problems that would affect all the pages that you print, whether you print in color or in black only. The topics that follow list the typical cause and solution for each of these examples. Problem Print is light or faded on entire page. Sample Print is light or faded in a particular color. Image is too dark. Cause Solution Poor contacts exist on the ITB unit and the product grounding unit. Clean the grounding contacts. If the problem remains after cleaning, check the contacts for damage. Replace any deformed or damaged parts. Poor secondary transfer contacts exist on the secondary transfer roller and the ITB. Clean the contacts. If the problem remains after cleaning, check the contacts for damage. Replace any deformed or damaged parts. Poor primary transfer bias contacts on the ITB unit and product. Poor primary charging bias contacts with the print cartridge and product. Clean the contacts of the color that produces the light print. If the problem remains after cleaning, check the contacts for damage. Replace any deformed or damaged parts. Poor developing bias contacts with the print cartridge and product. The RD sensor is defective. Replace the RD sensor. See Registration density (RD) sensor assembly on page 209. Page is blank. The high-voltage power-supply lower is defective (no developing bias output). Replace the high-voltage powersupply lower. See High-voltage power supply lower (HVPS-D) on page 250. 614 Chapter 3 Solve problems ENWW