Printer and Photocopier Troubleshooting and Repair Collection : Copies too dark 2                       
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Copies too dark 2

"Canon NP-2015s ... prints very dark, with "water stained" appearance. All controls full light gives a 'readable' copy with a dark grey background. I have been told everything from 'wrong toner' to moisture in the toner. The guy who brought it to me doesn't know. Before I vacuum out the toner & stick a $25 cartridge in it, could this be a bias problem?"

(From: Bernard Morey (bmorey@aardvark.apana.org.au).)

Have you tried cleaning the corona wires? There are generally two modules. Pull out and clean with cotton-swabs (Q-tips).

(From: Lionel Wagner (ck508@FreeNet.Carleton.CA).)

If your dark grey background is not uniform, you will have to vacuum out ALL the old toner, and thoroughly clean the roller that transfers it to the drum. Do not use abrasives, as the surface of the roller is very critical. If this restores even grey background, you can think of adjusting the bias voltage.