LaserJet 2100 - multiple pages fed even after pick-up roller and separation pad replacement

[davegrabo]

Hi,

I've got an old and up until now very reliable LaserJet 2100.

After experiencing some paper pick-up problems, I replaced the feed rollers and separation pads for the MF tray and the main tray. Pick-up from either tray seems to work fine, and always picks up a single sheet at a time.

However, when feeding from the main (bottom) tray, often (but not always), a second sheet will get fed into the printer AFTER the first sheet has been picked up and fed through (i.e., the end of the page has entered the printer). It's almost like I'm printing a multiple-page job, even though it's only a single page (i.e., regular test page). The first page exits the printer normally, and then the printer stops (paper jam error) with an inch or so of the second sheet sticking out of the exit slot.

With the covers off, I can see that the solenoid is engaging to let the feed roller turn to bring in the first page, but often remains engaged a bit too long, so a second sheet gets picked up *after* the first sheet is completely picked up.

The service manual glazes over how the various signals from the paper sensors are used (or for that matter, even where they are located), so I'm somewhat lost as to how to troubleshoot this further.

Any ideas?

[davidzuts · Accepted solution]

This is a common issue on older printers. Your issue is the tray 2 pickup solenoid which controls the movement of the tray 2 pickup roller. It is very hard to get to it and you will need the service manual. What happens is when you send a print job the main gear assembly turns and the solenoid which controls the tray 2 pickup roller activates and moves it's "L" arm to release the roller and then power is turned off to the solenoid and the "L" arm which is spring loaded returns to stop the pickup roller before it can turn again. HP used some dampening material on the solenoid to quiet the clicking noise of the solenoid activating. Over time that material wears off and all that is left is the glue that held it in place. When the solenoid activates the "L" arm hits the center and the glue residue prevents the arm from returning back in time to prevent it from stopping the roller and hence another sheet is fed. You have to access the solenoid which is behind the main gear assembly on the right side. Takes a lot of work and you will need the service manual. Once you have access to the solenoid, you remove it, unhook the spring and remove the "L" arm. You then clean off the glue residue off the ledge of the solenoid and any on the "L" arm. You then put some felt material down on the ledge where you remove the glue. Put everything back together and it should work another dozen years without issue. Good Luck.

[davegrabo]

I just returned to my post to follow up with my successful results.

Your post coincided EXACTLY with what I discovered as I dug through this thing further. When peering inside the printer, I saw that the latch on the solenoid wasn't releasing. When I opened up the printer enough to get to the solenoid, I was shocked to see that the latches (both) had sticky stuff on them.

I used some isopropanol to clean off the goo, but didn't bother replacing with felt; I'm not too concerned with the clickity-clack while printing. I did the same thing for the solenoid for the manual tray, since I was already all the way inside.

However, it was still sometimes doing the same thing. Even when not energized, it seemed that the solenoid has some residual magnetism - enough to hold the latch in place. Probably simply due to lots of use. I think the long-term fix is to just replace the solenoid, but for the meantime, I just stretched out the spring a bit so there's some extra tension to bring the latch back when the solenoid disengages. So far, so good.

Thanks for the confirmation!

[davidzuts]

You always have to put down new material or you will get what you are getting. The solenoid does not need to be replaced. A small strip of electrical tape or part of a velcro strip will work just fine.

[Hardbackwriter]

I had the same problem, disassembled the printer (lots of work---keep a log as you remove each piece to get to the solenoid, so you can reassemble when you're done.  I cleaned off the arm and put a strip of black electrician's tape where the silencer pad had been and it worked fine.