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Unread 25-03-2008, 09:48
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AKA: Alex Yeckley
FRC #2252 (Mavericks)
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Re: HELP: Internal Solenoid Leaks Killed Us!

Quote:
Originally Posted by IndySam View Post
I find it very difficult to believe that three brand new one were bad right out of the box?
I do too, which is why the problem was so consternating. Usually a pattern like that points to user error (translation: my error), but I just haven't been able to figure out what we could have done wrong, especially given that we did have one working Festo, albeit from the 2007 KOP. There's just not that much that we could have done wrong, and I think we've worked through all the possibilities other than infant mortality.

My initial guess when we identified the first problem was that we'd somehow overtorqued the mounting screws and distorted the plastic case, causing the pilot to bind, but we rejected that theory after we had the same problems with the unmounted replacement valves.

If we'd wired up things wrong electrically, then we shouldn't have had a good LED indication, nor should we have had a good 12V measurement on pins 1 and 2. The silkscreening on the valve body indicated that it was a 12V part, not a 24V part, so I think we have to reject that theory as well, unless it was mislabeled.

If we'd plumbed things wrong pneumatically, then we should have had the same issue with the 2007 KOP Festo, but we didn't. When the valves were swapped, the problem followed the valves.

If the infant mortality rate of the Festos in the 2008 KOP really is 50% (which it honestly seems to be, based on the reports I'm reading from other teams) then it isn't really surprising that we'd get three bad ones in a row from the parts desk at the regional. The real question is how could the IMR be that high? The most obvious possibility is that the 2008 KOP valves were units that had issues on the production line, and rather than scrapping them they were donated. I'm not prepared to make that assertion just yet since it has some pretty negative connotations, but right now it's the best explanation I've got.
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