asked Oct 6, 2005 at 10:49am
Hp HP LaserJet 5SI


I have been through the many threads on the forum that address the failure of trays 2 and 3 to lift. All of them pretty much say, "Replace the PIU." Can anyone address the problem with the PIU that causes this failure to occur? I have two 5Si machines: one that lifts properly and one that does not. I have had both PIUs apart completely (and put back together) and I cannot find one difference between them. I have looked at the gear teeth, the spring tension, cam wear, etc., but I cannot seem to find the problem that causes the one to fail. Does anyone here have any knowledge of the PIU geartrain\\internals that could shed some light on this failure-prone beast?? It seems prudent to find the offending individual part(s) and replace as necessary rather than the unit as a whole. This assertion may not apply to those who need to hire a tech to fix their machine and wish to have it done quickly, but to those DIY folks that have time on their side and the ability to do so, some supporting information would be greatly appreciated.

Thanks and good day!
the board on the side has caused problems for me in a couple of rare cases...
internal clutches can cause the jams that plague these PIU assemlies...especially tray 3 no-pickup problems, the ones we encounter the most...

However, the highest failing part is the second pass feed roller. you can change the second pass feed roller yourself, once the PIU is out of the printer...we do this repair all of the time. if it's at all shiny, this will cause jamming before the registration assembly.

the gears don't wear out, at least not that i've ever seen.

no real information other than what's off the top of my head.
by chris on Oct 6, 2005 at 1:11pm Add comment
I think there is a motor which lifts the trays or moves the gears which lift the trays. If the motor is bad the tray will not lift.
by dmzcompute on Oct 6, 2005 at 1:17pm Add comment
there is a motor. seware74, what error do you get?
by chris on Oct 6, 2005 at 1:24pm Add comment
Well my experience with the PIU is don't mess with them. We've tried to rebuild them, its way too much work involved & failure of the device very high anyway. First off I've been told HP sized the Registration Rollers too small(Big round ones under the registration) & failure of those can occur any any point.

We've had to replace PIUs around 150,000 totals pages up to 1 Million pages. The bad ones tend to go out sooner, I've seen the rollers so worn out it caused jamming from Tray 3 only, or sometimes from either tray. I've fixed broken springs under the lift arms only to have the registration rollers get worn out. At one point our company was buying refurb. PIUs but we had too many problems that we now refuse to get them refurbed & only do New.

All refurbs. that we had put in have failed, some lasted 2yrs then failed. Cost of the news can run $250 - 300 easily, some vendors we have give us deals where we get new, exchanges (meaning we send the bad one back for a price break)
by Sharpie on Oct 7, 2005 at 11:04am Add comment
One thing to check, have you tried moved paper trays around since you have one that works? Its an easy quick thing to try, almost always it's in the PIU but hey never know till you try.
by Sharpie on Oct 7, 2005 at 11:06am Add comment
I got the fool thing to work!

It turns out that the torsion spring (PN RS5-2477-000) is supposed to be mounted on a little nub molded into in the main plastic body of the PIU. On both tray 2 and tray 3 the nubs had broken off so that the springs were sitting cockeyed enough to interfere with the movement of the roller holders (PN RB1-6585-000). I removed the springs and the lifter links (PN RB1-6544-000)and removed the broken plastic nubs. Then I fashioned some pivots to replace the nubs out of (chuckle here) dry wall anchors and positioned them to do a better job than the original nubs did. Better yet, they can't break off because they're not attached. Putting the spring and lifter link back in for tray2 was a pain but doable. And amazingly enough it all worked splendidly! Gave the whole thing a vacuum job and a once-over inside and out and voila it works fabulously and looks nearly new.

P.S. It seems from my newly acquired intimate knowledge of the PIU internals, that aside from things like broken nubs and failed motors, the main things I see that would go wrong with the PIU are:

1) worn rollers
2) worn or stripped gear teeth
3) worn clutch cams\\arms
4) broken springs in the drivetrain
5) dirty \\ broken sensors

All of these things are easily replaced (I know because I've had them all out and back in). And replacing a few cheap parts is certainly cheaper then replacing the whole PIU (dollar-wise, maybe not time-wise).

Just my own observation. Thanks for the help folks.

by seware74 on Oct 8, 2005 at 10:56am Add comment
If you need a tech job, let me know. I would rather have a creative tech than a book-learned one. - moe
Looked at time wise it's something most companies can't afford to do.

A rebuilt PIU costs around $100, the company I work for figures that counting overhead a Tech's time costs them about $50 per hour, so if you spend more than 2 hours on something like that you are wasting money.

Practically speaking I disagree, but management and I don't always concur, and as long as they keep sending a paycheck I'll be happy to go ahead and replace whole units that could possibly be fixed.

Another side to the argument is that I fix a lot of machines on a time and materials basis, if I tear apart someones machine and replace a second pass roller and that doesn't fix it I'm supposed to then replace the PIU and charge them for the rebuild time and the replacement time. (Then I have to reinstall the used parts in the original PIU)
by Stephen on Oct 8, 2005 at 7:15pm Add comment
Stephen your boss is right on this one. A rebuilt PIU from a company like will come with at least a 90 day warranty and will contain many new parts including the 2nd pass roller, new pickup rollers and gears. When you just replace the 2nd pass roller it may solve the problem at hand, but keep in mind other parts which have a tendancy to wear out are not replaced or at least inspected for wear which may cause the PIU to fail for another reason a short time later. In the over 100 PIU assemblies I have replaced over the years, I can only remember 1 which had to be replaced under warranty after about 2 weeks due to failure.
by dmzcompute on Oct 8, 2005 at 7:40pm Add comment