HP LaserJet 4MP faded print

[dferreyra]

HP LaserJet 4MP faded print

Hello,

The printouts from our LaserJet 4MP are coming out pretty faded compared to how they used to look. It's very noticeable on serifed fonts like Times Roman, and on dithered backgrounds.

This is on a newly opened, genuine HP toner cartridge. BTW, the labels on the toner cartridge box indicate that it was manufactured in July, 2007. Can old toner be the culprit?

Increasing the print "density" to its maximum of 5 helps but doesn't come close to the darkness I used to get at the default density just a few months ago.

I did a "halfway" test. The unfused toner looks faded just like I'm seeing with a normally printed page. If I flip up the drum shield on the toner cartridge and look at the print on the drum itself, it looks faded, too.

I've tried cleaning the toner cartridge contacts on the printer. This seemed to improve things a little, but that improvement was gone the next day.

I've brushed the beam-to-drum mirror. It looks clean to me and had no effect.

I've looked under the laser/scanner assembly shield and wiped the focusing lens with a dry cotton swab. It looks clean to me and cleaning had no effect.

I've wiped the transfer roller with a dry cloth with no effect.

I'm considering buying another toner cartridge to see if that helps, but I'm afraid it will be a waste of money.

Any idea what this might be? Any input would be greatly appreciated!

Dean

[Big Al]

Have you tried another Toner Cartridge? If so then it has to be either the high voltage power supply or a weak laser. The halfway test is independent of the formatter board. Might be time to go up to a 5n, they use the same toner cartridges and NIC. Did you clean the rotating mirror? I have seen a few times when strange problems were cleared up by reseating the formatter board three or four times but I doubt that is your problem. Toner cartridges usually have a very long storage life if kept under reasonable conditions. Over the years we have received a few genuine HP cartridges that did not work well.

Please let us know what you find if you get it fixed.

Al

[dferreyra]

Hi Al,

Thanks for your response!

No, I haven't tried another cartridge yet. I'll see if I can pick one up today and give it a shot.

I didn't clean the rotating mirror. If the new cartridge doesn't fix this, I'll look into doing that. Unfortunately, I don't have any experience repairing printers -- everything I know I learned this weekend from reading parts of the service manual, browsing the Internet, and reading this forum!

Thanks for the suggestion of the 5N. My wife is an accountant and would love for us to have one. BTW, our 4MP uses a 74A cartridge while the 5N looks like it uses a 98A cartridge.

Dean

[Big Al]

Sorry, I missed the model of the printer. Take the cartridge back where you bought it and ask them to test it. They are guranteed by HP. Did you shake the cartridge well before installing it?

Those "J" printers are difficult to repair. Sounds like you are low on the learning curve but are making rapid progress.

The older LJ4, 4+ and 5n are real workhorses. Sometimes you can pick one up very cheap. About the only things they need are the two feed rollers and the pickup roller in the main paper tray. I do a lot of printing at home and my LJ4 is slow but very reliable. Even bought an envelope feeder for it and that works well too.

Al

[dferreyra]

The most I'd done with the cartridge was gently rock it back to front and side to side. After your message, I shook the cartridge pretty strongly, but the printouts are still faded.

Since your post, I took apart the laser/scanner assembly. The rotating mirror and various other small lenses and mirrors looked perfectly clean to me, but I wiped them all gently with cotton swabs anyway. I also wiped the back side of the focusing lens. The printouts did not improve.

I don't know where we bought the cartridge, probably Staples a year or two ago. It had been sitting in our house, unopened, on a shelf. I'm still planning on trying a new cartridge. Maybe if that one works, I can contact HP directly to return this one.

Thanks again, Al.

Dean

[redcow]

See if you can pick up a transfer roller. That will affect print quality. On those older printers we used to take the transfer roller and wash it with water in the sink, dry them good and reinstall it. Once you get the paper dust washed away it makes a big difference.

[dferreyra]

I just tried a new toner cartridge, but the print did not improve.

[dferreyra]

Thanks for your response, redcow.

I just tried cleaning the transfer roller with water, also with no improvement.

At this point I don't think the transfer roller is the main problem because the "halfway" test showed me that the print was faded on the photosensitive drum even before transferring the image to the page.

[dferreyra]

Just a quick update, I've given up on the 4MP and I've bought a refurbished HP LaserJet 4000TN from PrinterTechs.com.

I bought the 4MP new in 1994 and it's done well until now. Now I just have to figure out what to do with it.

[MichaelTech]

Remove the high voltage assy, under the printer and clean the contacts wires on the board. They look like staples, use a brush.

[dferreyra]

MichaelTech, thanks for the suggestion. I'll give it a try when I get the chance, though I don't know how successful I'll be. From what I remember from the service manual, getting to the high voltage assembly was a lot more disassembly than I've attempted so far.

Dean

[RogerF]

Remove the high voltage assy, under the printer and clean the contacts wires on the board. They look like staples, use a brush.

I have the same problem as the OP: very faded prints. No error codes on self test. Halfway test shows almost no toner on the drum. I followed your advice to clean the HV contact wires but it didn't solve the problem. If the laser were weak, would I expect to see an error code? Or is it time to replace the DC controller board assuming the HV is failing?

Thanks!

[woodss]

Just a quick update, I've given up on the 4MP and I've bought a refurbished HP LaserJet 4000TN from PrinterTechs.com.

I bought the 4MP new in 1994 and it's done well until now. Now I just have to figure out what to do with it.

Might be good idea to retire the old thing but sometimes dust can get inside the laser scanner usually a blow with compressed air can fix these problems, but 4MP are very slow, 4ppm, the 4000TN is a much better unit.

I personally use a 4300DTNS, which has duplexer, and 3 500 sheet bins and a stacker tray, this unit was made in October 2003.

Used since 1994, thats nearly 20 years so it has done its job really well, my junk internet printing printer is the HP LJ II Its now 23 years old, Jan 1988, and just had its regular annual yearly service, every year on the month it was made the printers I have a annual service mainly cleaning the inside and inspection of major parts. such as rollers and the fuser.

When I see these problems, I check the laser scanner for dust and transfer roller.