We got a new Phaser 7500 in our office about 8 months ago. Just recently we have started having a problem where any areas of black are printing very weak to the point where they look more like 30% grey. Other colors don't seem to be affected. We had a local technician come by, but he couldn't fix it or give any explaination. We are a design agency, and use the Phaser for outputting presentations, etc, so we need to find a solution right away. Any help is much appreciated!
I would first be sure its not file specific, and try a "known good" file. Better yet, create a new test pattern with 100% black and see what you get.
Also knowing whether you have recently changed computers, software, or updated would be helpful.
What kind of media are you running on?
You probably need to calibrate the machine, and calibrate for paper. If that does not make a difference, then replace the black drum.
It definitely isn't file specific, as it affects everything from MS Word to Adobe CS5 and CS6 files; and even the built-in test documents print poorly.
One thing I have found is that the problem goes away if you use an RGB profile instead of CMYK. I set up a document with vector squares 100% through 5% black, and the same scale as a raster image. The results were the same across all apps until I printed the test from a document set up as RGB, or chose an RGB profile in the print menu. I don't see this as a long term solution, but it works in the meantime.
There are no notable changes to computers or software.
The media is just standard laser printer paper, and off-brand toner.
Try cleaning the laser window, there maybe a wand that does this in front of machine where the doors open up for service. There also could be a problem with the developer housing or the developer itself may need to be replaced.
I recommend you talk with your local Xerox reps and maybe start a contract for service with them