Odd power supply issue

[synaesthesia]

Bit of an odd one someone might have an idea of!

 

Got a call this morning from a department saying their office PC wasn't working. Sure enough got there and it was sat with all fans whirring at max speed but no power LED or any actual function from it. Odd - brought it up to the office, it worked perfectly fine. Took it back down, didn't work. Tried it in the class next door, didn't work. Tried it in a class a few doors up - worked (all with different power cables). This is a Stone PC.

 

Put another power supply in, perfectly fine. Put that power supply in another machine, tested it in that department; nothing, yet again it's fine everywhere else.

 

All I can think of is that something's occurred to make it particularly sensitive to something - but what? Poked a multimeter in the sockets down there and everything seems well within limits.

It's currently sat next to me whirring happily away.

[JRowley]

Had a similar issue with a HP DC5750 a few years ago, after walking it around most of the school I took it back and plugged it back in and it has been fine since then, never found an explanation for it.

[Oaktech]

Power supply is knackered mate. Get a new one...

 

I've had literally hundreds of stone PCs (and RMs that share identical casework and PSUs) that exhibit exactly that fault. It is caused by an under spec'd capacitor.

[synaesthesia]

We've got a fair few of these Stones and this is the first one to have done this. I intend to pull it apart at some point to have a nose. Not something I'd expect from an FSP supply mind, and can't find any information relating to common issues elsewhere - it's an FSP300-60GHT

 

Hope they're not too bad, we've just ordered 15 PSU's from Stone to replace a load of RM ones that a faulty electrical board blew up last year!

[peterp]

Does sound like a noisy power supply. Either the input or output filtering capacitors not doing their job.

You could try plugging a surge protected power adapter in between the wall socket and the psu. These work by having meaty filtering caps take much of the noise off the input supply.

If it were too much ripple on the output side of the psu I'd expect it not to work anywhere.