asked Nov 2, 2011 at 6:21am
Hp HP LaserJet 4100

HP 4100MPF - 13.1 PAPER JAM (intermittent)

I am a copy tech. working on an HP 4100MPF with 336K copies. I am getting the accursed 13.1 paper jam, but unlike most of the posts about it, it is intermittent for me. Most of the time, the paper is barely ejected from tray 2 when it jams. I have also experienced it slightly picked up AND I have experienced the blank page, but only once. The customer says she has experienced blank pages also.

I separated the engine assembly from the paper assembly and examined the pickup clutch. The foam pad has not worn off and as I actuated the latch, it seemed completely fine. It was not sticking to the foam. While I had the assembly separated, I also examined the pickup assembly gears - they were all in good condition. Not missing teeth or anything.

Both feed/sep. rollers look fine also. I cleaned them with fedron (rubber-restoring solution) for good measure. I also tried feed rollers off of another 4100 the customer has. Still no good.

The torque limiter also seems okay. I tried the torque limiter from the other machine too. It's possible that they BOTH could be bad, but I seriously doubt it.

In addition, I have examined and cleaned the pickup rollers and examined their crank shaft and spring. All is well.

I have not yet watched the paper pickup from the rear of the machine since this does not happen on every copy, but that is my next thing to try, because it seems I've tried everything except replacing the entire pickup assembly. I just don't see what would cause blank pages except for that clutch.
The easy way to tell if the clutch is the problem is to remove the clutch and put the roller back on the shaft. It will be loose but will still work. Now see if you get any 13.1 jams. If not then the clutch is the probable cause. If the old style that separates you can separate into the 2 pieces and remove about 1/3 of the metal filings and put back together. Another item overlooked is the actual paper tray. There are two white plastic pieces one on each side that hold the metal piece up and are spring loaded. Sometimes one of them is missing and can cause paper jams. The other item overlooked are the half moon rollers which can sometimes wear but that would be rare as I have seen them last to 1 mil. Hope some of this helps.
by dmzcompute on Nov 2, 2011 at 4:07pm Add comment
1cer22x, I had a similar problem. It turned out that the plastic lip upon which the tray rested was slightly worn. The tray wouldn't sit high enough for the rollers to catch the paper properly every time. We built up the ledge with a thin plastic shim and the problem disappeared. Just a thought. Hope this helps.
by unknown on Nov 2, 2011 at 5:46pm Add comment