asked May 23, 2005 at 3:40pm
Hp HP LaserJet 3100

HP LJ 3100 print quality - Electrical noise?

I have a Laserjet 3100. I am stumped with the problem I am experiencing.

The engine test and printouts have 'noise' on them. I scanned an example - please see

I've replaced the scanner assembly with a new one as well as tried three toner cartridges and the problem remains.

Every once in a while, a perfect page will print, but it isn't often.

Any ideas?
Do a half test and open the toner door to stop the printing. Remove the toner and look at the image. It will most likely be bad. Now look at the remaining image on the drum of the toner. If it is ok, then the problem is most likely the transfer roller either the roller itself or the metal springs which send the charge thru the roller. If the image on the drum is also bad, then it is the optics, toner, I guess maybe the high voltage or even a low voltage issue on the main board. If the image on the paper is good, then the issue believe it or not is the fuser assembly smearing the print.
by dmzcompute on May 23, 2005 at 3:54pm Add comment
The half test resulted in defective image on the toner drum -- given your description, it would appear the suspects are optics (and I replaced the laser/scanner; both old and new gave same results, so that probably isn't it), toner (I tried several known good toner cartridges from other 3100's, so that probably isn't it) and high/low voltage. Given these three possibilities it looks as if the high/low voltage is suspect.

I checked and cleaned the three high voltage pins - and still have the problem.

Dang. I've put about $75 in parts into this printer to this point and am a little frustrated. I guess the next logical step is to replace the ECU board, and if I was positive this would solve the problem, I'd consider it. - tgitech
Thats the problem. If you have the time and the inclination, I guess you could swap the ecu from one machine to another. Another old hp tech trick is to remove all the connections going to the ecu and putting them back on. Sometimes over time one of the connections gets loose and in your case maybe something is arching causing the issue. Just a thought.
by dmzcompute on May 23, 2005 at 6:02pm Add comment