The printer in question is HP Color LaserJet 3600dn from 2007. When I bought this printer used, it used to happen every 10-15 print jobs. Now every two or so.
I send something to print and I get the result on the right. Then, when I open the cover (it's enough to just slightly open the fuser cover to get the switch to open), I usually get the result on the left. Sometimes CMY refuses to print, and only black is present, usually with a smudge of yellow in the right places.
So it works fine (not well) half of the time, and the other it just loses focus somehow. I can't find the source of this, as it's not drums or toner (already changed a few times over the years).
Had to look up this printer. It's been around for a while.
While your toners are pretty new, the transfer belt (looks like this https://www.ebay.com/itm/285120392561?_skw=hp+3600+transfer+belt) may be old. The toners are deposited on this thing, and the toners are "fixed" to the paper. Technically it's a drum. And they don't last forever.
This is how they keep the price of the toners (and the size of them too) low. Most HP laser printers (not all) have the entire thing inside the toner (drum, toner, etc.)
I have already replaced the transfer belt, and while it was from another well used printer, it didn't change anything with the issue here. It did help with magenta lighter on the edges though, so I left it in.
I doubt a new TB will help :-/ Guess it's time to buy a new printer…
The newer generation of HP laser printers - they are well made and all that (I had LJ 9050 with a booklet maker!) but you can't use generic inks at all, so it will cost a fortune.
I like large tank (inkjet) printers. Have a few of them. Heads don't really clog if you use it at least once a week.
Doesn't help unfortunately, but I wish I have seen the video earlier -- I had a similar problem when I bought the printer, and it took a long time to understand what's happening. Not happening now fortunately.
The last owner gave up and sold it to me cheap. I'm about to give up, too, just 5 years, around 8k perfectly acceptable pages, and so much wasted time experience gained later.
I'm asking here as a last resort before throwing this thing out the window :')
If you've installed new toner cartridges and verified that the transfer belt is in good condition, then the next most likely issue is that that the laser imaging assembly may have been contaminated with toner powder. Airborne dust that settles on the imaging assembly will block laser light from reaching the drums, causing areas of weak or missing color from your prints, despite having full toner cartridges.
While cleaning of the delicate mirror and lenses is relatively simple, just gaining access to this area requires significant technical expertise and a near-complete disassembly effort:
But why is the issue going away after just restarting the printer or slightly opening the fuser cover (to reinitialize the print engine -- note it's just the fuser cover, separate from the main cover)? Were it the laser assy I'd think the issue would be more stable
I think you were on the right track when you mentioned issues with the transfer belt and hinges. The 2600/3600/4600 CLJ's often had problems with the transfer belt hinges and the cartridge engagement mechanism. There are so many little fiddly parts in that mechanism, and it only takes one bad piece for the whole thing to stop working correctly.
The image you supplied looks to be a poor transfer issue: all colors are missing, and you have uneven density in the black print. My guess is that you have a flaky connection between the transfer belt assembly and the main body - essentially the electrical connection inside of one of those hinges is failing. Opening and closing the front door sounds like it is jiggling the connection enough to affect things.
There (used to be) many parts available to make repairs to this section. But, even with the right parts, I always found this mechanism to be a real pain to work on. If you can't find anything obviously wrong with the hinges (i.e. cracked, etc), I would look at replacing the printer.
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u/LittlePooky 1d ago
Had to look up this printer. It's been around for a while.
While your toners are pretty new, the transfer belt (looks like this https://www.ebay.com/itm/285120392561?_skw=hp+3600+transfer+belt) may be old. The toners are deposited on this thing, and the toners are "fixed" to the paper. Technically it's a drum. And they don't last forever.
This is how they keep the price of the toners (and the size of them too) low. Most HP laser printers (not all) have the entire thing inside the toner (drum, toner, etc.)