Maximising Laserjet Black Print Density

ANSWER : Try this test. Put a page into the manual feeder and do that same test. When the end of the page is just about to enter the printer, open the lid. Take out the toner cartridge and pull back the shutter. Look at the image and see if it is black. The explanation is that there is high voltage going to both the toner cartridge and the charge transfer roller below it. If the image on the drum is black, then the fault is at the transfer roller not getting enough high voltage. The transfer roller pulls the image off of the drum and down onto the paper. It would not be a laser scanner problem as any issue with it would not result in an overall gray image, but combination of gray and black. It will probably turn out to be a bad HV power supply, which will need replacement. I’ve never seen this particular problem on this model.

ANSWER : That model had issues with the carousel solenoid sticking. That might explain why it works after you let it sit for 10 minutes. The solenoid gets hotter with use which causes the deteriorated foam on it to become sticky and hold down the release plate instead of letting it go. This allows the carousel to spin when it is supposed to stop for each color. The solenoid is located on the right side of the printer. If you open the lid, it is just behind the opening at the top right. You need to remove the top of the printer and scrape off the goo on top of the solenoid body. I put a piece of thin sticky backed felt to replace it. Other people use electrical tape.

ANSWER : Find someone with a HP LaserJet 4100 and you can configure the card to the IP you want:

ANSWER : You need to unlock the carousel. Once you unlock it and remove the toners, ignore all the rest of the crap. Pick any color and align the cartridge slot on the left side like you would have it to remove the cartridge. Then pull out on the gear towards you on the right and drop it so the right slot is lined up as well. You can get it aligned pretty close by just eyeballing it visually. I’ve never seen the left side go out of alignment, just the right, so this method has worked for me everytime.

ANSWER : It looks like a fuser problem. One way to prove it is with the half-stop test. Put a sheet in the drop down manual feed tray. Send a print job and watch the paper. When the end of it is about to enter the printer, open the lid and take out the toner cartridge. Look at the printed image. If it looks OK, then it is a fuser problem. If not, then it is a toner cartridge issue since it hasn’t gone through the fuser.

ANSWER : Been working on these since they first were released. Never seen a problem like yours. If it happens again, try doing an engine test, as it bypasses the formatter board. The engine test is located at the right side of the manual tray opening. Look for a hole in the side wall. Stick something like a paper clip into it to actuate the test button. It will then print a lined test page. If it does that, then it points to the formatter board as the cause of your problem.

ANSWER : Take out the toner cartridge and look at the drum. If you see the line, replace the cartridge. If you don’t, then you need to replace the fuser assembly.

ANSWER : Don’t know why you replaced the fuser, but assuming you had print before, then it must have been something you did during the procedure. Only thing I can suggest is to recheck your work. Just because you reinstalled a connector doesn’t mean that it is seated firmly enough to work. Any flat ribbon connectors that you removed and reinstalled, check to see that the contacts are all flat and not peeled back.