Re: Testing a PC Power Supply Output

[pslists <pslists@xxxxxxxxx>]

I always have to check the pinouts online, so I can't give chapter and
verse, but PC power supplies generally don't "turn on" or turn
off again
quickly unless certain criteria are met. If you've got a digital
multimeter, select the 20v DC range, otherwise be sure to get the
polarity right when testing.

* Provide mains is present, there should always be a +5v standby
supply available, but no other voltages.
* Shorting the "power on" pin to ground (black) and then
providing
mains power should give the +5v, +3.3v, -5v, +12v and -12v
supplies. Check each in turn with respect to ground (black).
* However, some power supplies will quickly switch off again unless
there is a load to drive, you could plug in an unloved hard drive
to provide this load.
* Even if all this works, you may find he power supply will not give
stable performance with your motherboard. I have sometimes tried
several power supplies from the bits box with a computer that
mostly works OK, and only regained long term stability by getting
a new power supply. What that really means is that a multimeter is
not the last word in test tools for power supplies.

Pete

Mark Golledge wrote:
> Afternoon all,
>
> I need to test the output from a PC power supply. I have a multimetre
but
> I'm not sure how to go about testing.
>
> As I've not done this before and do not really want to place myself in
> hospital(!!) I want to get some advice. Can you let me know how I'd go
about
> doing this - and whether the power supply needs to be connected to
anything
> (i.e. motherboard and hard drive).
>
> Any advice would be much appreciated - don't worry, I'm not going to
test
> until I feel confident about doing this!!
>
> Many thanks,
>
>
> Mark
>
>

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