[CentOS] died again

Mon Dec 16 17:46:35 UTC 2013
Warren Young <warren at etr-usa.com>

On 12/15/2013 16:49, Michael Hennebry wrote:
> Looks like I'll need to see whether I still have my multimeter.

That's not likely to tell you much.

About the only thing I'd trust a typical DMM to tell me about a PSU is 
whether its rails are within voltage spec.  You must do that test under 
load, and you need a fairly accurate DMM to get a result you can trust.

If the PSU passes the voltage test, it could still be bad.  The only way 
to tell, short of just swapping it, is to do an ESR test[*], which 
requires an LCR meter.  (It also requires removing the PSU board from 
the box, which exposes you to the dangers of AC wiring and charged caps.)

I don't think I've ever seen a DMM with an integrated ESR function.  If 
such a thing does exist, the DMM would end up being pretty expensive if 
it gave results you could trust for this, since we're talking about 
measurements under 1 ohm.  Decent LCR meters start at about $200 and go 
way up from there.  Cheaper to just gamble on a PSU swap.

[*] https://en.wikipedia.org/wiki/Equivalent_series_resistance