clj 2840 printing black horizontal lines

[madmextech]

I am working on a clj 2840 that is printing/copying black horizontal lines evenly spaced about an inch apart on every copy/print. I know this is a repetative defect. Can someone help me with determining whether I need to purchase a new drum unit or if it might be the transfer roller. I have no service documentation....:confused:

[Big Al]

First, is the printer under warranty? Are they using genuine HP cartridges? We have had a lot of trouble with color laser prints using some refilled cartridges. Many of the refillers are now sending the image drums out to be resurfaced. These resurfaced drums have a brown photosensitive coating. We got a bunch of them. Our purchasing department ignored us and bought refills. The cyan cartridge was putting a blue line across the page every 92 milimeters. I do not think this is your problem.

Start by downloading a service manual. You should be able to find one free on the Internet. In the book will be a repetive defect page that should help you isolate the issue. You can also go into the firmware and disable CARTRIDGE CHECK. You can then take out the black toner cartridge and see if this clears up the issue. You can also swap the black with another color and see if it follows the black cartridge. I cannot be more specific because I am not familiar with that printer. Please let us know what you find.

Al

[cs_steve]

Just from experience a Transfer roller rarely makes print defects other than light print...

The drum is a good possibility. If the lines are only printing "black", it very likely could be the black cartridge as well.