HP 4550 Service Manual - Page 82
Approximate replacement intervals for consumable items, Imaging drum life - maintenance kit
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Approximate replacement intervals for consumable items Imaging drum life Images versus pages The life of the imaging drum (about 25,000 pages) is stated in terms of A-4/Letter-size images. The number of images printed for each sheet of paper varies, depending on the mix of color, type of format, and whether duplexing has occurred. The following guidelines will help determine drum life: An "image" is a layer of toner. An A-4/Letter-size color page printed on one side contains four A-4/Letter images, one for each color (CMYK). A duplexed sheet counts as two pages. In color duplex mode (printing on both sides of a page), there are eight A-4/Letter-size images per A-4/Letter sheet. The page count numbers on the Configuration Page give a count of the number of pages printed, regardless of size. For example, an A-4-size color duplexed page takes eight images to print, but only adds two pages to the page count. Usage patterns How the printer is actually used can also have a significant effect on drum life: Because of pre- and post-rotations, the drum wear is approximately the same for a one-page job as for a two-page job. Frequent short jobs will decrease the drum life. There are extra rotations and cleaning cycles when printing duplex pages. Duplex jobs use the imaging drum at a higher rate than comparable simplex jobs. "Drum life low" versus "drum life out" The DRUM LIFE LOW warning message on the control panel indicates approximately 20 percent of life remaining. This is intentional to allow the user enough time to order a replacement kit (C4195A). It is perfectly acceptable to continue to print while the DRUM LIFE LOW message is displayed. However, when the DRUM LIFE OUT message occurs, the drum has reached the end of its life and the printer will not operate. Key points to remember The drum life specification assumes two-page jobs, one-sided printing on A-4/Letter-size pages. When printing in color (four images per page), the number of pages will be 1/4 of the images printed. Due to the carousel arrangement of the color cartridges, color printing uses four images per page even if only one color is actually used. 80 Printer maintenance C7085-90921