HP LaserJet 4000 paper feed issues again.

I got some good help here last time to fix a paper jamming problem with the lower drawer in my HP LaserJet 4000. It was the sticky solenoid issue in the main paper tray. Now I have a different issue with the way the paper doesn't feed from the manual (upper) tray. The pick up roller starts to move just a small amount, then it stops. If I don't intervene, I get a paper feed error. If I do intervene and give the roller a push, it will get the paper loaded. Then there's a pause, and I see it try to move again. Then I have to push it again. Then all goes well. Is this the other upper solenoid? I cleaned them both last time I had it apart. I thought a sticky solenoid causes the opposite problem where the paper won't stop loading. It used to be intermittent but now it happens all the time.

Thanks for your reply.

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David Farber 
Los Osos, CA
Reply to
David Farber
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Yep. Common problem. I think that there is (not sure) also a solenoid INSIDE the paper tray frame that can also cause paper feed jams. I couldn't tell for sure from the exploded views:

More:

Sure sounds like a solenoid problem. The feed roller is not locked in the correct position on the first attempt. It then rotates around maybe 300 degrees, gets to where it should be, and starts to push normally. However, it doesn't finish going around a second time, and just stops.

It might also be how thick the felt you attached to the solenoid armature. If too thin, the armature will stick to the magnetized coil core. If too thick, the armature pawl will rub against the cam, and possibly stick.

Offhand, I would guess(tm) that it's the feed roller and it's accomplice the separation pad. Just buy a kit on eBay and replace everything. For example:

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Hi Jeff,

I removed the tray assembly 1 (that's the manual feed unit) and looked for any irregularities. I couldn't find any. The solenoid was not sticking. The felt I put on from a few months ago was attached and still looked new. I was trying to follow the drive train sequence that ends up turning the manual feed pickup roller but it wasn't so easy. I didn't feel like tearing down the entire chassis. So I put it back together and for now, it's working again. It would seem to me that it couldn't be a roller problem if the mechanism stalls out and giving the pickup roller a little push gets it going again. The page count is over 40,000 now. I wonder how many new printers last that long.

Thanks for your reply.

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David Farber 
Los Osos, CA
Reply to
David Farber

I was referring to Tray 2. Unscrew the well hidden screws holding the Tray 2 assembly to the printer, and the tray and the tray mechanism should fall off. Take it apart and I think you'll find yet another solenoid. I'm not sure and have no easy way to check right now.

I hate it when that happens. It should fail again just when you need the printer most.

I beg to differ. The timing of the paper feed is controlled by the solenoid you fixed. Mangle the timing in any manner, and it will act something like what you've described.

On the 4000/4050/4100 series, I have so replace the rubber parts, some gears, and rebuild the fuser at about 50,000 pages. Much depends on the environment. In a really clean office, I can sometimes go to about 75,000 before anything needs replacing. At a local auto shop, I'm lucky if anything prints 10,000 pages before something goes awry. The worst was a machine shop, where everything was coated with a mixture of metallic dust and lubricant, which operates like an abrasive. I have 4200/4250/4300/4350 printers in tax preparation offices that show well over 150,000 pages. The trick here is that I do a pre-emptive cleaning and roller replacement every year before tax season. That's about $25 in parts, $75 in labor per printer. After I started doing that, I've had no after midnight phone calls from the tax customers demanding I run over and fix their overloaded printer. The most I've seen on a printer was a LJ4+ with over 250,000 pages. It didn't die from overuse, but rather fell apart when someone dropped it during an office reorganization.

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Jeff Liebermann     jeffl@cruzio.com 
150 Felker St #D    http://www.LearnByDestroying.com 
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Reply to
Jeff Liebermann

Surely this is a typo. Did you mean 400,000?

400k on a 4000/4050 is no big deal for a machine in daily & heavy use. On an EX-engine (4,4+,5) this is just getting broke in.

For your Tray 1 problem you need a RG5-2651 clutch. They're $29 at Printerworks.com

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Reply to
David K. Bryant

Hi David,

No, 40k is correct. It gets light use now. I acquired it used about 7 years ago.

Regarding the clutch which I found at

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I was wondering, is there one particular part in that assembly which causes the failure?

Thanks for your reply.

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David Farber 
Los Osos, CA
Reply to
David Farber

The electromagnetic clutch on the end of the shaft. Failure modes:

not engaging always engaged slipping

Usually the latter. This is evident when the paper feeds but not all the way thru. Paper Jam error message often means that the paper failed to reach a sensor at the right time.

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Reply to
David K. Bryant

Is the clutch serviceable or is not worth the effort?

Thanks for your reply.

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David Farber 
Los Osos, CA
Reply to
David Farber

Certainly not worth the effort and possibly not even serviceable.

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Reply to
David K. Bryant

Hi David,

I finally disassembled the printer again to look at the electromagnetic clutch and the related components. I put DC on the clutch terminals and manually turned the gear that the engine normally turns. I could feel the magnetic field pushing on the opposite end but the gear near the clutch did not engage. It seemed like something should have changed after energizing the clutch. Then I removed the gears and clutch from the shaft that held them. That's when I found that same type of sticky grease on the shaft that was present on the solenoids that caused a paper jam failure months ago. I cleaned the grease off with some alcohol, reinstalled the clutch and gears, and this time both gears turned when the clutch was energized with DC. I reassembled the printer and now paper processed through tray 1 works properly every time. It turned out to be an easy fix but I never would have thought to look in that area of the printer without your suggestion so thanks very much for that. (-:

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David Farber 
Los Osos, CA
Reply to
David Farber

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