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One of the HP LaserJet 4100s in my office has a problem that is hard to describe. I'll link some scans of the pages it prints below so that you can see exactly what is going on. My best guess is that it is printing vertical lines in the wrong order.

Here is a list of things I've already done to solve the problem, none of which seems to have had any effect at all:

  1. The printer asked for a maintenance kit, so I purchased and installed the requested kit per the provided instructions. The maintenance kit included a fuser, so note that the fuser has been replaced.

  2. I messed around in the printer settings and changed things like pitch, font, etc. None of which worked. After all of that, I reset the settings back to factory defaults.

  3. I've replaced the toner just for the heck of it, with no improvement in print quality.

  4. I tried printing configuration pages from the printer itself with the data cable detached, and the problem persisted. This tells me that drivers are not the issue.

Here are links to scanned versions of my printer output. There is nothing wrong with the scanned images, they represent the printed pages well:

Cleaning page:

Cleaning page

Configuration page:

Configuration page

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Thank you for the help, much appreciated. – Gabriel Aug 9 '11 at 19:49
Stupid question: You're totally sure you're using the right driver, right? – Doc Aug 9 '11 at 19:53
I've eliminated the possibility of a driver issue by printing out configuration pages with the computer disconnected from the printer. Also, when I replace the malfunctioning printer with a working model of the same series (which accepts the 4100 drivers), it prints without any errors. It is not a driver issue, at least not on the computer. – Gabriel Aug 9 '11 at 20:02

It sounds/looks like a fuser problem, but if you changed it and it made NO difference then that's kind of weird. :)

A user or two on have a few ideas on tracking it down:

Do a half test. Put a sheet of paper on the manual feeder and run a self test from the menu. When the sheet is about 2/3 of the way in, open the top cover to stop the printer. Remove the toner and look at the image below. If it is distorted look at the remaining image on the drum of the toner cartrdige to see if it is distorted. If the image is ok, the fuser is the most likely cause. If the image is distorted and the toner drum is the same, it is most likely the high voltage or laser/scanner optics.

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Excellent idea techie007. I tried the half test as you instructed, and the image on the drum is indeed the same as the image on the page. – Gabriel Aug 9 '11 at 20:19
If it's like that on the page and on the drum, then you're looking at probably a power (supply), or an optics problem, neither of which are 'user serviceable'. Sounds like it's time to contact an HP repair center to figure out if it should be repaired or replaced (if not cost effective to fix). – Ƭᴇcʜιᴇ007 Aug 9 '11 at 20:23

It looks like an optical fault or a fault with the opto mechanics - ie: the scanner mechanism is not running correctly so the laser scan pattern is distorted. A lot of that stuff is not user serviceable but you could check that the portal through which the laser beam shines is clean/clear and that the gears and cogs that drive the rotating bits (fuser, OPC drum and anything user replaceable that rotates) are not fouled with a bit of paper or anything that will stop smooth rotation. After that, it's a strip-down by someone who knows the printer.

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I like your line of reasoning. I only hesitate to come to those conclusions because the vertical line are consistently out of place and still very sharp. If the optics were not clean, I would expect the image to be blurry or distorted on certain vertical lines and not others. If a cog was jammed or loose, I would expect that the patterns would change after running a hundred or so pages through it, but that isn't the case either. The distortions are sharp and consistent from page to page. Edit: This does lead me to a useful train of thought though. Perhaps the firmware is borked? – Gabriel Aug 9 '11 at 20:36

It looks like a drive system problem. Have you verified that you installed the correct fuser and that the drive link between the fuser and the paper feed system (gear driven I'm sure) is correct? It may be that the fuser and drive system aren't meshing, causing the drive system to "jump" which would affect anything driven by the same drive "train", such as the drum. fuser, and paper feed.

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Upon comparison, the old and new fusers look identical. I'll take a closer look anyway. – Gabriel Aug 9 '11 at 22:30

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