Thread: PC power supply to 12v power supply

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So I've read through most of the how to s

I've shorted the thing to power on, and hooked some PC fans to it and they spun so i was happy.

I went and got my medusa's fixed to their board and wired, but before i wired the PC power supply to it I used my meter to check the voltages, they were scattered.

So i read through some of the other how tos and it said to add a resistor, well i didn't have one so I added several fans, and the voltages still haven't stabelized.

The pc was fine when it got put into storage, so I don't believe it has gone bad.

Any thoughts?

Thanks,

Not sure what might be going on there. If I remember right, the yellow wires are 12volt, the black wires are 5volt. Measuring on those outputs, what variations are you getting?

I'm starting to think my meter is screwed up.

Yellow is 12v, Red is 5v, Black is common

If i put it in a wall outlet I get 120v, if i switch to DC and take a AAA batter I get 1.5v. If i do 2 AAA end to end i get random voltage. I just tried a 12v supply that came with a nerve center and it was doing the same random voltage the PC power supply was, when i say random it is shooting from 0v to 75v(on the PC supply and the two AAA end to end), i know there is supposed to be some fluctuation in it but not that much.

I have a thought, Take the damn multi-meter out and smash the heck out of it. Just went out to the garage and put it on a car battery.

Guess what.............................................. ................................................. Random voltage, so for some reason anything above 1.5v dc won't read on the meter now, but AC works fine.

wasted hours grumble......

You might try replacing the batteries in your meter. Weak batteries can do strange things...

Sure can. Some DMM's use the battery voltage as a reference, and when it goes low you may get some errors.

BTW, where did you get those 75V AAA batteries?

You should still put a sandbar resistor in it whenever you get a chance to go by Radio Shack. But yeah, sounds like someone tried to use the multimeter to read 120AC while in DC mode

Harbor Freight, $5, just as good as the $20 models at Home Depot. You really need to get into the $50+ range for a multimeter to be significantly better than a super cheapie one.

You were using it in DC mode, right? I don't think measuring AC while in DC mode would break anything. Either mode is capable of measuring large voltages in each direction. I'm pretty sure it's just that AC mode does RMS conversion.

Maybe there's an intermittent connection in one of the probes? Try putting it in resistance mode, connecting the probes together, and them moving/bending the wires around. If you intermittently read anything higher than ~0, you've got a broken wire in your probes.

But yeah, if it's really the meter, that's pretty frustrating. There's nothing more annoying than having test equipment lead you astray.

- Hook

Well, new meter and i'm testing at 12.02v and 5.23v stead on my leads

In other news I've got some 75v AAA batteries for sell, includes a multimeter to prove they are 75v only $19.95 CALL NOW..........

Yep, I had a nice multimeter that cost a bundle and it went bad on me. It just became a useless POS and I spent $40 on it. I replaced it with a $12 model from my local electronics store and life is good again.

Definitely get the sandbar resistor for your hacked PS. I hacked 3 this year and they work great.