Dell desktop PSU failure

[graham998]

Hi!
I'm a bit new to this forum so I'm still getting used to things on here. I just had a few questions. I've recently been tasked with figuring out why a bulk quantity of Dell optiplex PSU are failing. I guess my main question is, does anyone on here know what the main cause of a desktop PSU failure is? I have a Huntron but at this point I do not have a good working unit to compare the bad units to.
Any help would much appreciated. Thanks.

 

[shrtrnd]

I don't know the circumstances of your situation. It SOUNDS like either a design flaw or a production run that incorporates some out-of-manufacturer-specification-tolerance component.
I'm speculating that all of the power supplies have the same failure? If so, I'd concentrate on verifying that the fault is the same on the majority of the units.
It sounds like you're unfamiliar with some troubleshooting skills. Is it possible for whomever tasked you with this job, to give you a fully functional unit to compare your voltage reading test points with?
To answer your basic question, power semiconductors are prone to failure due to heat/high voltage stress. And electrolytic caps are prone to failure for the same reasons.
With an issue like the one you face, it's difficult to pin-point the problem from our end, because the failure could be as simple as a small resistor or capacitor opening-up due to a design issue or out-of-tolerance component.
Have you opened one of thes units up yet to look around? Maybe something physically burned-up and you can isolate the problem that way.
If you can, can you give us any more information about what you were told about these units when you were tasked with the job?