asked Nov 29, 2002 at 9:12am
Hp HP LaserJet 4050

HP 4050 Duplexer

I am experiencing more than normal paper jams in my HP 4050 Duplexer - Any suggestions?
and thanks,
You could try using some of our rubber roller rejuvenator on the rollers inside.
by moe on Nov 29, 2002 at 9:25am Add comment
I had the same problem with a LJ-4000 duplexer unit and was told by another technician to clean the roller bushings and to remove the original grease as it is too thick but I was unable to seperate the duplexer unit to check.!!!
by Craig on Nov 29, 2002 at 2:17pm Add comment
Try (scotch tape) taping the top flap of the duplexer and the back flap of the duplexer together - tightly. At least for me I have found this to work. Good luck! Steve
by unknown on Jul 17, 2005 at 9:50am Add comment
To fix 4050 duplexer paper jammimg: Try (scotch tape) taping the top flap of the duplexer and the back flap of the duplexer together - tightly. At least for me I have found this to work. Good luck! Steve
by unknown on Jul 17, 2005 at 9:52am Add comment
Remove the 6 silver screws from the duplexer bed.

Remove the bed.

That will expose the 2 rollers. Clean them up with rejuvenator or whatever.

Replace the bed and the 6 screws.

Now prise off the cover with the power plug (it's difficult, but it will come off), underneath you will find the gearing.

The gearing is tensioned by a spring clip on the large gear. Remove the clip, E-clip and the large gear wheel.

Squeeze the clip to re-tension it. Replace the clip, the E-clip and the gear, replace the side cover and run the duplexer.

Oh, I hate duplexer's. Too fiddley.

by Trev Pearson on Jul 17, 2005 at 11:00am Add comment
Hi Trev,

So to take off the duplexer i just unscrew 6 screws and it should come apart. Is there any wires or clips attatched to the printer itself? I just want to expose the rollers so i can rough them up a little.

max - Anonymous
No wires, no clips. It's a plug-in unit. Have a go.

by Trev Pearson on Oct 13, 2005 at 10:57am Add comment
Credit another fix to Trev.

> I can now guarantee that my duplexer is 100\%
> operational, I fixed the problem by using Trev Pearson's
> suggestion, I would like you to post on FYOP on my behalf to
> thank Trev for that post even thought i wasnt for me but it did
> work.
> I would like you to post it in the forum, they would listen to
> you and also say in there that I am truly sorry.
> Stuart.
by Stephen on Jan 23, 2006 at 5:34pm Add comment
Trev Pearson, your fix worked like a charm. Thank you very much for taking the pain out of duplex-printing.

by unknown on Mar 16, 2006 at 9:17am Add comment
When duplexing photos, two darker streaks occur only on one side when the paper goes through the duplexer. Does not happen when using single side mode. Should the duplexer be cleaned or is there something else wrong.

by unknown on May 28, 2006 at 6:46pm Add comment
Trev Pearson, your fix instructions are still bearing fruit in November 2009. I partially disassembled my hp4050 duplexer to clean the rollers after the printer began having duplexer jams every 80 pages. Cleaning the rollers didn't help -- it seemed to jam more often.

So I followed your directions about tightening the clip that provides friction to the big gear, I've printed about 1000 duplex pages so far, and no jams. And I don't get that nasty clunk sound on page feeds through the duplexer.

I print the books I sell and was out of inventory. I thank you and my customers thank you.

Steve Litt
by stevelitt on Oct 31, 2009 at 9:57pm Add comment
Sorry to say, Trev is no longer with us.
by moe on Oct 31, 2009 at 10:26pm Add comment
Hello. I am having a paper jam problem with my 4050 duplexer. It gives a 13.10 error (Paper Jam Check Duplexer). I always have to pull the sheet out of the back of the duplexer after the first attempt to duplex. I've tightened the spring clip, but that did not work.

For at 2 page document, page 2 prints fine. the sheet goes all the way into the duplexer and gets stuck after that - when it's being pulled back through the duplexer so it can re-enter the printer. When I looked at the position of the sheet when the error occurred, the top edge was about 2 inches before the rollers. (I can send a photo if that would help)

I can't seem to find the rollers responsible for pulling/pushing the paper through so the 2nd side can be printed. There are 4 white plastic rollers under the green page diverter thing; are they the cause of my problem? Is this problem even roller-related?

Also, why is it printing page 2 first and not page 1? (I would guess this is how it's done so the pages are properly arranged in the output bin)

Thanks much!
by uiucsb on Feb 22, 2010 at 2:07pm Add comment
well the paper goes into the duplexer, through the back ,down to the very bottom where it stops and reverses. Goes back up and out towards the front feed assembly. It sounds like you have taken it somewhat apart? I would take the right side cover off and watch the gears and see exactly when it is happening. As always check the very bottom for paper. seen that before.
by nivek on Feb 22, 2010 at 8:43pm Add comment
Thanks for the reply.

I have taken the duplexer apart. I quickly tried to disconnect the electrical plug on the right side cover so that I am able to see the gears as the printer is working. However, I wasn't able to connect the duplexer and see the gears at the same time.

Some more questions.

1) Is there a roller wheel deep inside duplexer (hidden)? If there is, has anyone replaced it?

2) Is the small, metal (brass colored) gear the motor?

3) Depending on which way I rotate the brass gear, the big white gear (with the spring clip) will move and engage one or another gear. However, no matter which way I manually rotate the brass gear, the front roller wheels rotate in the same direction (although much easier in one direction). Should reversing the direction of the brass gear also reverse the direction of the entire gear system? Can anyone send a photo or diagram of all the gears and which direction they should rotate?

4) What do those fine hairs do? They are located near the front of the green part and go across the paper path.

by uiucsb on Feb 22, 2010 at 9:20pm Add comment
Its been awhile since I've taken one apart so Im afraid I cant be to much more help with the operation. The fine hairs are for antistatic. Im confused with the side cover thing. I run them alot with the side cover off but that just usually becuase I dont have the proper power cable. Unfortuanely I dont pay to much attention to the gear movement. I wish I would of saw this post last week becuase I worked on a few with duplexers so I would of paid attention to help you better. Sorry.
by nivek on Feb 22, 2010 at 9:42pm Add comment
Trev Pearson rules in 2013 as well...

FYI, if you lose the e-clip like I did when taking it off, you can bend a paperclip to work... at least for one print ;-) We'll see how it goes once the user starts using the duplexer full-time!
by [email protected] on May 10, 2013 at 6:53pm Add comment

Trev's suggestion still works in 2017 -- The tension-er on the big gear seems to work for me
I have only a few test pages so far -- but it is better than what I was getting before (every single piece jammed )

by db_the_dba on Aug 22, 2017 at 12:11am Add comment