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View Full Version : Crossload protection?


370forlife
06-19-2009, 10:50 PM
I have a little 350w Rosewill psu I use to power fans if maybe its getting hot in my room or I need to spot cool something, when it gets hot I stick two nidec 240cfm sunfire 880 server fans in the window running on this psu.

Well, the deer made rosewill ate itself the other day, so I decided to just use this little useless astec 200w psu from a hp vectra vli8. I hook up the fans, they reach about 500rpm each and the psu shuts itself off. Strange.

Then I figure "duh, theres no 5v and 3.3v load, so its crossloading, and this is group regulated"

So I hook a old maxtor 5400rpm hard drive to a molex connector, and walla they spin right up and do their job for hours on end now. So was the cutting out caused by some sort of crossload protection or probably just 5v sense? Would a crossload situation like a higher 12v draw cause the 5v to go too high? These fans are only 1.85A each, but who knows how much they use when spinning up. Or is it possible it has 12v sense, too? Its got a little chip on a riser board that the fan is connected to, its right next to where the output wires connect to the pcb. Its a astec AS2333C, only info I can find on it is that its a "house keeping circuit"

I'll have to disconnect the maxtor and plug in my DMM to see what the 12v voltage is before it cuts out, right now its too late and rainy out.

Travis
06-19-2009, 10:51 PM
Light-load protection maybe.

370forlife
06-19-2009, 11:01 PM
http://www.datasheetarchive.com/search.php?&q=as2333

First link seems to answer my question.

Yup, it does 12v, 5v, and 3.3v undervoltage and overvoltage. (well, 3.3v is a option, which is obviously not on this one providing it ran with only a 12v and 5v load)

So must have been throwing the 12v low with absolutely no 5v and 3.3v load.

Wow I just noticed it only has 6A on the 12v rail. In that case I think I might just convert my astec 425W ibm Z-pro psu into a lab psu/fan psu. Its independently regulated with 12v and 5v under and over current protection, too. That runs both those fans just fine without having to add a hard drive that has a extremely high pitched whine.

Travis
06-19-2009, 11:10 PM
Check it with a DMM.

370forlife
06-19-2009, 11:33 PM
Sorry, I edit my posts alot.

Without the hard drive on, it cuts out very quickly. I can't get a reading quick enough.

With a hard drive connected, the 12v reads 11.51V, and the 5v 5.18V.