HP d640 HP D640 High-Volume Printer - User Manual (Printer and Accessories), C - Page 179

Maintaining Print Quality Specific Print Quality Problems All sample pages are shown in Letter size and portrait orientation. Similar problems may show up on different paper edges, depending on the paper feed Fading If a white streak or a faded area appears on the page (in the direction the paper passes through the printer): • Check the Economode setting; be sure it is OFF. (See "Economode" on page 2-17.) • The moisture content of the paper may be uneven, or there may be moist spots on the paper. Print several dozen test pages with paper from a newly-opened ream. • The print density setting may be too light. Adjust the print density. (See "Density" on page 2-25.) • Toner may be on the transfer charger or pre-charger corona wires. Clean the printer's transfer assembly unit and precharger. (See "Transfer Assembly Guide" on page 5-9.) • Replace the developer in the printer with new developer. (See "Replacing Developer" on page 4-9.) • Replace the drum unit with a new one. (See "Drum Kit Replacing Drum and Transfer Assembly" on page 4-18.) • If you still have this print quality problem, contact your authorized HP service representative. Dropouts If faded areas, generally rounded, occur randomly on the page: • The moisture content of the paper may be uneven, or there may be moist spots on the paper. Print several dozen test pages with paper from a newly-opened ream. • The paper lot is bad. The manufacturing process can cause some areas to reject toner. Try paper from a different source. • Clean the paper feed path and LED array as described in "Weekly Cleaning" on page 5-1 and "Periodic Cleaning (When Replacing Drum)" on page 5-5. • Replace the developer unit with a new one. (See "Replacing Developer" on page 4-9.) • If you still have this print quality problem, contact your authorized HP service representative. 6-4 Advanced Topics