Ancient_Hacker wrote:


cm wrote:
Hello
I would appreciate it if someone would tell me how to test an atx power
supply with digital volt meter. (how to rig the atx plug to turn on the
supply so I can check it)
Thanks a bunch,
flubber

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I guess it depends how rigorous a test you want to do.

To do it right requires a bunch of high-power adjustable resistors.

To do it at all usually requires at least one substantial load
resistor, as most switching power supplies don't run at all with no
load.

And you do have to load down all the outputs, as a supply may be able
to put out 12 volts with no load, but not with any realistic load.

For very rough starters, get a 1 ohm 50 watt resistor and place it
across the 5 volt output, that will draw 25 watts. Or a half-ohm
resistor, that's 50 watts. Or more of these in parallel to draw
whatever wattage you want to test at.

Same for the 3.3 volt output, only there a one ohm resistor draws about
10 watts.

For the +12 output, a two ohm resistor draws about 70 watts, a one
ohmer 144 watts.

For the low-current outputs like -5 and -12, a 10 ohm resistor draws
2,.5 watts and 14.4 watts respectively.

Oh, there's also the always-on outputs, be sure to load them too.

the formula is watts = voltage squared over ohms.

or watts = current squared times ohms.

Go ahead and have fun, just don't burn yourself on the hot resistors!



pins., then ground the remote startup pin for a second, then go ahead
and measure the voltages.

Thank you, you've helped a bunch. I had forgotten about the remote
startup... thanks again

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