rohmellasked Apr 23, 2008 at 5:40pm
Laserjet 4000N: transfer roller hold down problem
I have a LaserJet 4000N with a transfer roller hold down problem.
My company was going to throw this printer out, but it prints OK except for the printout being slightly darker and smudged (or out of focus?) on the left side of the page. This is being caused by the transfer roller being closer to the paper on one side than the other. The transfer roller does not have a clip to lock down the axle into the paper feed mechanism on the right side. The spring that is on that side allows the roller to rest higher on that side than the other side, where there is a clip that holds it down and retains it under spring tension. I can't tell if the transfer roller is missing a clip, or if the paper feed mechanism is missing a piece of plastic, because I compared this printer to a LaserJet 4's transfer roller, and that one has one clip on the left side, and the right side sorta snaps into place into a kinda 'c' shaped protrusion on the paper feed mechanism.
Is the LaserJet 4000N supposed to have a similar 'c' shaped section for the right side of roller to snap into, or is there an additional piece that goes there? The paper feed mechanism does not look like anything is broken off of it. The service manual does not have close-up pictures of this area, so I can't tell the correct way for the right side of the roller to be held down at the correct height in this printer
The answer your question above there is nothing on the transfer roller on the right side except for the metal shaft which is held in place by the white plastic holder on the right side.
Paper-feed guide assembly
1 To remove the paper-feed guide assembly:
a Remove the rear right side cover.
b Remove the control panel.
c Remove the top cover.
d Remove the left side cover.
e Remove the front right side cover
f Remove the rear cover/rear output bin.
g Remove the fuser assembly.
h Remove tray 1.
i Remove the tray 1 pickup assembly.
j Remove the right side toner cartridge guide.
k Remove the registration assembly.
l Remove the formatter assembly.
m Remove the printer drive assembly.
n Separate the engine module from the paper-feed module.
o Remove the engine controller board.
2 Remove the plastic main gear cable guide by releasing the three tabs.
3 Loosen the plastic formatter ribbon cable guide.
4 Disconnect the paper-sensor cable.
5 Remove the two self-tapping screws.
6 Carefully remove the paper-feed guide assembly.
Note The engine controller board grounding spring might interfere with removal.
AFTER TOSSING A 4000 AND A 4100 to parts only status.STEADY AS YOU GO AND BE PATIENT.
STEP BY STEP AND YOU HAVE BECOME AN "E.X.P.E.R.T"....Thats
a drip under pressure. Ha Ha
I drilled a small hole in the plastic and used a part of a straightened paper clip to bridge across the broken part and apply downward pressure against the spring.
The roller is now at the correct height and the printing is perfect.
Send me your email and I can send you a pic.
Since a repair would actually mean replacing a "sub Chassis" (and a heck of a lot of work) I just hoped for the best, re assembled everything else (just bought a roller replacement kit), and everything works great. I don't know, however, what long term will bring. I printed out a few jobs, and all of them are great. NOW, I WOULDN'T SUGGEST to break off the opposite end that is still holding, but as a last resort??? My situation was if it didn't work when I tried it out, was I most likely would have sent it to the trash.
If someone has any thoughts on this I would appreciate it. As I said, I don't know what to expect long term. Thanks for all your help on this site!!!
I then cut a ~0.25" section off a paper clip, heated the end cherry red using a torch lighter, and just pushed it into the plastic post where the original stop broke off from.
The right side is a far easier to do than the left, but after some trial and error it works. If you mess up the hight, make sure to pull the paper clip piece out before it cools, or you risk breaking off even more plastic. In the same vein, make sure you don't melt the catch on the U piece of plastic when you're checking the height.
Even if you mess up a couple times, there's quite a few different ways you can fashion a small bent wire to melt into the plastic and be at the right height/angle. On the left side, the post was so ruined after so many attempts, I just used a ~0.5" section of paperclip and pushed it in to some plastic farther back, then because it was a bit loose with all the torque from the U bracket, I braced it by taking another bit of paperclip and melting it into another part of the printing frame so that it crossed over the first piece. That way the U bracket pushed up against both of them, which ended up working perfectly.
With trial, error, and some ingenuity it's doable, but it might take longer than 30 seconds.
Can anyone post any photos of the fix? I broke off that small plastic that holds down the right side white piece where the transfer roller turns? It is such a delicate piece of plastic in the LaserJet 4000TN. Any help or further guidance would be greatly appreciated, especially pictures. Thank in advance.
I've got a similar issue, but nothing appears to be broken.
When I removed the transfer roller, the small plastic part that rests on top the spring on the left side popped off, too, but does not appear to be broken. However, when I put it back in place, it moves freely up and down on the spring, but doesn't "clip" in anywhere to remain in place, so the roller isn't stationary.
I'd consider gluing it in place, but I don't know the actual, proper height/position for it.
I have the same problem as jr hender posted above. Nothing appears broken but left side will not snap in and lock when I turn the black open end of on the left side of the transfer roller down and try to insert it. The little black cap that sits on the top of the left spring will slide off and it does not appear to be broken. Any ideas of problem or easy fix without expensive and time consuming replacement of the whole assembly
Adding the ability to include pictures would be super helpful
Why is everybody fiddling around with paper clips? This is the BEST fix for a busted retaining plastic piece on the right clip of the transfer roller. It will probably work on the left side for the black clip as well. It's obvious the existing spring is TOO long now. So what we have to do now is craft a spring that is just short enough to work.
First remove the clip. Pull off the existing spring. Find a retractable ballpoint pen, you know the ones with the clicker on the top. Open it up and pull off the spring from the ink refill. Keep in mind the nub underneath the transfer roller clips are of a certain size so you need to make sure to find a pen with a big enough spring to snugly fit over it. Try to check this first before busting open and ruining a pen.
This is where you have to do a bit of trial and error. The objective is to make the clip pop up and give just enough push on the transfer roller so that it hugs the toner drum but not too much.
Snip off a reasonably shorter portion of the spring, try it on the clip and see if it raises it just over the plastic assembly. If it doesn't then it's TOO short and you have to try again. Make it longer. You can make the spring longer by stretching it out slightly with a pair of needle nose pliers.
If it does work out, insert the transfer roller and make sure it's level. Not too high and not too short. Again, there has to be some slight springiness to the roller but not too much. Make sure is it as close to horizontal as possible. Eyeball it all the way across. It should be reasonably even and not lopsided.
Congratulations. You've just saved yourself a ton of trouble of replacing the entire paper feed assembly.
So are there any ill effects to NOT pushing down the roller with the clips?
My clips broke, but since the roller stays in place I didnt bother repairing it. The toner cartridge goes right in, and my printouts are perfect.