No Stats for PSU, How can I multimeter it?

[beau_safken]

Howdy Y'all,

Well I appreciate all your help for finding a correct PSU for my new rig. I found a 400 watt PSU but got no stats on it but for 8 dollars and for an unopened retail unit that can't be too bad. Im a little concerned about the quality of the PSU but 8 bucks really.....

What I need to know is how I would be able to use my multimeter to find all the relevent stats for this unit, and What are the most crucial stats for overclocking? Little bit of a newbie but hey never know until you ask. :)

Beau

[rogerdugans]

All I know is how to check with a meter.....
but for $8 I'd buy it!!!!

Might have something to do with being cheap......:beer:

[beau_safken]

Well It was a Mis-Spell auction on Ebay, the RSPS was 59.99 but got it for 8 bucks... Could be a piece of junk but then again could be a candidate for a peltier supply if It doesn't fuel my whole system.

But yea I am a little worried, but thats just lunch money:p

Beau

[rogerdugans]

Jump it to get it running, and check for 5v on the red/black and 12v on the yellow/black.

Then find an old pc and plug it in:D

[beau_safken]

Gratz!!! I'll keep you all posted on how this bargain buy turns out, If it rocks I'll make sure to tell everyone....Soon as it gets here that is..

[Warren G]

Ok, I'm dumb at this. I just got a multimeter, but where you I the red one and black one in? I know the its the 5v (red) and 12v (black) but do I plug it rite into the 4 pin hole?

[rogerdugans]

Four wires go to the molex:
Red, black, black and yellow

red is 5v, yellow is 12v.

I usually use the black right next to whichever one I'm checking, but I don't think it matters- they are both ground.

And I just stick the meter's probes right in the holes....just don't short 'em out!!!

[Warren G]

short em out?!?!?!? :eek: how would i avoid doing that? and
THANK YOU rogerdugans now Im ready to test my 5v line, heh

[dew042]

Originally posted by Warren G
short em out?!?!?!? :eek: how would i avoid doing that? and
THANK YOU rogerdugans now Im ready to test my 5v line, heh

many of the the four pin connectors have four metal pins that float around in their holders.... it is not that hard to press the 12v or 5v so its touches the ground and poof your psu might be dead, but probably just switches off. eitherway it sparks and scares the hell outta your ..... not to say its ever happenned to me or anything....:rolleyes:

dew.

[macklin01]

Funny thing is, I just did this yesterday on a PSU.

Stick the black probe in one of the black wires on a 4-pin connector and leave it there the entire time. Then, use the red (positive) probe to do all your probing. (I've found from experience that if you try to move both probes at the same time, you're much more likely to short something out.)

Then, to test the voltages, move the red probe around. I'd recommend not touching any of the pins on the same 4-pin connector that's holding the black probe. This way, you have absolutley zero risk (well, really, really small) of causing a short. There are plenty of 4-pin connectors, and they should all read the same, so this won't make a big difference.

Test the yellow (+12), and red (+5) on the 4-pin connectors. Then, test the ATX connectors. You should see a lot of +5V wires (red), maybe some +12V (yellow), some +3.3V (orange?), as well as some -12V, -5V, -3.3V.

There is one drawback here. You won't be able to find out the CAPACITY of the lines using this method. (e.g., 1.5A at +3.3V, etc.) But if it's at all like most PSU's, these values should be printed on the actual unit.

If you need to make that measurement yourself, I think we could rig something up. The test would go with something like this: (This will be a test for +5V)

1) Choose a current level to test. I'd recommend going in .1A increments. So, by Ohm's law, R = V / i = 5 V / .1 A = 50 Ohms.

2) Connect a +5V wire to ground with a 50 Ohm resistor.

3) Measure the +5V voltage (from a different +5V lead) as above. Call it V.

4) Compare V to the expected value of +5V. If it's close, you have at least .1A = 100mA capacity at +5V.

5) Choose the next resistance: 5V / .2A = 25 Ohms. Do the test as above. Repeat until you find a load at which the voltage dips below, say 4.95V.

But I really wouldn't do this unless you had to. (What a pain! :) )

Good luck, and have fun! -- Paul