HP LaserJet 4: toner line keeps forming on toner drum

[airspeed400]

I have an HP LaserJet 4. It prints horizontal lines across the paper, 3.75" apart. The lines come from toner stuck to the green clear roller in the toner cartridge.

This began 2 Years ago, when the printer started to accordion the paper as it exited the printer. I lived with pulling the paper out for a while, then broke down & bought a kit to replace some of the rollers. I only needed the exit feed rollers, but I replaced all of them, and some separator pads & pick ups, too.

The printer now feeds just fine, but from the time of the repair on, it has developed horizontal misprints on the pages. I don't know if it's related, but it was fine until I got inside to replace the feed & transfer rollers. I contacted the roller supplier, he gave me a new transfer roller, but it still has the problem with his 2nd replacement.

Reading the HP Combined Service Manual for the LaserJet 4/4M, 4 Plus/4M Plus, and 5/5M/5N, I learned (on page 7-41, table 7-19) that the

"possible cause"

"Toner Cartridge. The circumference of
the photoconductive drum is 3.75 inches
(94mm). The circumference of the
developer roller is 2 inches (51mm). If a
defect appears in the print image at
these intervals, assume the defect is
associated with the Toner Cartridge."

"action"

"Replace the Toner Cartridge."

So, I've replaced the toner cartridge, twice. At $95 each, I'm sliding into a hole, and fast! But I'm still getting the lines, 3.75" apart (about 3 across a letter-sized page).

If I leave the toner cartridge in the printer, I get more of these lines, a new one every time I leave it off for a while. If I use the printer & leave the toner cartridge in, I get a new line, in a new place (depending on where the roller stopped?) so now more show up on the paper. If I keep this up, pretty soon, there are lines everywhere, all horizontal.

I've also noticed that toner gets stuck to the "photoconductive drum" (green/clear roller) in the same, vague (looks like a sponge imprint) line. If I use a flexible plastic card (like a gift card) to scrape & some window cleaner to clean, I can get back to spotless, pristine prints when this roller is clean. But if I forget to take the cartridge out of the printer (and taking it out does get messy after a while), I'm back to the toner stuck across the green/clear roller and misprints unless I clean off the green/clear roller.

So, back to the Combined Service Manual, and

"possible cause"

"Small voids on black, or near-black
printed images may be caused by
imbedded toner on the
electro-photographic drum. Cartridges
that are run for long periods of time in
high temperature and humidity conditions
may develop this problem."

"action"

"Replace the EP Toner Cartridge. If the
printer is installed in a hot or humid
location, tell the customer to move the
printer to a better location."

How am I supposed to fix this? Two toner cartridges later, new, out-of-the box, and no improvement. The printer is not used for long periods of time, though I may leave it on for part of a day. It doesn't get a lot of use, it takes me 1-2 years to use a toner cartridge. The printer is in an air-conditioned room, maybe 74 degrees, I assume dry because of the A/C. Still, if I leave the cartridge in, I get the lines.

Obviously, this is not an okay situation. This is an excellent printer...when it works. It cost over $1,000 new, and I'm reluctant to let it go. I also believe in fixing things, not just tossing them on a lanfill & buying new.

So, what's wrong? Is there some sort of grounding problem to the cartridge? Did I undo something inside when I replaced the rollers, so creating the problem? Why does it only happen when the toner cartridge is in the printer, and not when it's out?

The lines match the lines on the 3.75" circumference green/clear roller, so I haven't looked past that. But there is toner on this roller, too, and when I clean it, all is well (for a time). The spacing confirms it is this roller.

So, what's going on here? NO ONE seems to be able to solve this...

PLEASE HELP!

To be absolutely clear:

The "image" on the clear/green roller matches the defect on the paper. This is not in question. If I clean this roller, the defect goes away. This is not in question. This occurs pre-fuser in the paper path. This is not in question.

What I am interested in solving is: what causes this toner to bond to the clear/green roller? If I leave the toner cartridge in the printer, switched on or off, for a few hours or more, this line appears on the clear/green roller, without the printer being used or the roller ever turning. If I take the toner cartridge out of the printer when it is not in use, I have no trouble, aside from toner everywhere after doing this many times, and the inconvenience. If I forget and leave the toner cartridge in the printer, I can pull the toner cartridge out before I print anything and find a spongy-looking toner imprint on the clear/green roller, centered across the exposed part of the clear/green roller. The nearest thing to the mark that appears on the clear/green roller is the spongy (pressure?) roller, and it exactly corresponds to the position of the spongy roller to the clear/green roller. Can the spongy (pressure?) roller be leaving the imprint on the clear/green roller, so the defect then appears on the green/clear roller? That seems to be what's happening.

What could be leaving this imprint on the clear/green roller while the printer is not in use? Is this some sort of grounding problem, or a fault with the quality of the non-HP spongy (pressure?) roller?

HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP! HELP!

[raz]

offhand,it sounds like there is an issue with the cartridge.this type of line can happen at the point where the scraper blade meets the drum.it's possible that it could be an electrical issue there.you could try cleaning out the cartridge slot and associated contacts there.

from what you are saying,it almost sounds like it is getting some excessive heat there at the cartridge.perhaps from a fan not working properly or from an issue wth the fuser putting out too much heat.

[redcow]

Replace the fuser

[MichaelTech]

Pull tray out. Set printer up on it's back.
Two screws, pull H/V assy. out.
Blow off all the toner/dust.
Re-install H/V.
Clean the toner contacts: Spring loaded, 2, and left side large flat contact.
Transfer roller may be extremely dirty.

[ptjeff1]

If I leave the toner cartridge in the printer, switched on or off, for a few hours or more, this line appears on the clear/green roller, without the printer being used or the roller ever turning.

From what you have said this isn't a fuser problem or a toner cartridge problem but a bad batch of aftermarket transfer rollers. Your supplier probably just sent another of the same batch. Try this experiment: take out the transfer roller (the spongy roller under the toner cartridge), put it on a white sheet of paper, put a little pressure on it like a small book, let it sit for an hour or two, see if there is a line on the paper. I tried this on a batch of defective 4000 transfer rollers and it only took 45 min for a line to appear. See the picture for what the line looks like on the toner cartridge drum. Make sure you replace the transfer roller with a genuine HP roller or a GOOD quality aftermarket roller.

[airspeed400]

Jeff:

You're the first person who has said what I have thought, that the transfer roller was not good. The supplier sent me another one, and I had the same problem immediately.

The line I get is a lot like the one in your photo, centered across the exposed photoconductive drum. Mine just happens to be wider, and looks more like an imprint from a sponge.

The supplier was convinced that the transfer roller being the problem was a longshot, because he said he only gets a bad one once in a very long while.

I will order a genuine HP transfer roller from another supplier. Do you want me to reproduce the problem, then send another picture? I'll try the book test you mention.

MichaelTech:

I don't know if you read, the transfer roller has been replaced...twice. I don't think it's a dirty transfer roller. It hasn't been used much, maybe 50-70 prints. If toner got on the new roller, I wouldn't expect it to leave a line on the photoconductive drum that's so consistent. It's almost like it's a mark from a sponge. What do you think?

I have used a vacuum to clean out toner/dust from where the cartridge installs, I'll try what you mention.

Redcow:

I can't see any evidence that this is a fuser problem. Would you explain why you think this has something to do with the fuser?

A line of embedded toner appears on the photoconductive drum, exactly where the transfer roller is positioned. If I clean the line of embedded toner off of the photoconductive drum, the print errors disappear. This all happens pre-fuser in the paper path.

Raz:

This is the second new cartridge, so I've been assuming the cartridge is good. I'll work on those contacts you mention, the cartridge slot has been vacuumed.

Would you expect any smell associated with the overheating you describe? I sit right next to this printer, and it has never smelled like it's hot or overheated. The fan souds like it's working as it always has.

What should I do to investigate this?

[raz]

when you say ,"spongy,pressure roller".if you are talking about the transfer roller.it's not really a pressure roller .it's a positively charged roller that charges the paper and pulls the negative charged toner off the drum onto the paper.
if not the cartridge or transfer roller itself or contacts in the cartridge slot.perhaps an issue where the transfer roller ends make contact where it seats in.is the housing where the ends of the transfer roller seat in ok?and the transfer roller fully seating in?there is a guide there right by the transfer roller also;did you wipe out the paper path by hand around there?perhaps some toner spill there or something.
you would think the issue would be right in that area somewhere.

[ptjeff1]

Here's another idea. Put a piece of paper under the toner cartridge and install the toner cartridge over the paper. This way the paper will be between the toner cartridge drum and the transfer roller. Leave it sit for an hour or two. If there is a line on the back of the paper you know the problem is the transfer roller.

Parts re-sellers usually don't test aftermarket parts. They buy from distributors and simply trust the distributors to do the testing, which often doesn't happen. There is also an increasing number of counterfeit HP parts entering the country that get passed off as OEM.

[redcow]

I think that it's the fuser because if the toner that's on the drum appears to be baked on the drum, I've seen the problem before, not on a LJ4, but on a LJ4000. Every toner cartridge I threw into the printer ended up the same way, in the trash.

After changing all the electronics in the printer to no avail, HP support found a service note...told me to change the fuser. I did and the new cartridge continued to supply toner until the "change toner" message appeared. About a year later I saw the problem again on a different printer. The fuser fixed that one also.

Sorry about rambling on like RAZ, but you asked.

What ever the fix...please let us know.

[airspeed400]

Thanks, gentlemen, I am doing what you suggest. I ordered a genuine HP transfer roller from the HP website. I hope that is the best way to ensure it's genuine.

I will do the test with the paper between the rollers.

In the mean time, here's a picture of what my photoconductive drum looks like, after being left in the printer more than one once.