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Convert an ATX power supply into a regular DC power supply Answered

I did this project https://www.instructables.com/id/Convert-an-ATX-Power-Supply-Into-a-Regular-DC-Powe/ just today, but all the results came out negative voltage (e.g. -11,45 on the 12v) on the multimeter. Did I do something wrong or is it supposed to be like that?


Do you have your multimeter leads crossed? (Assuming that your using a multimeter...)

Leads are fine and labeled anyway. All in all Im calling this one a success. It powers my 12v styrofoam cutter (homemade of course) just fine. Also tested it on some 12v pc fans and some other odds and ends.

How do you power the Styrofoam cutter? ATX Power supplies cut out when they are short-circuited, and since the path has such low resistance I imagine it would cut out.


9 years ago

Sorry for the back to back posts but heres the device in question.


depending on your power supply, 12 volts may not be yellow. I think on mine yellow = 3.3 volts

Yellow is coming up -11.45 on the meter

then that may be -12 volts from your powersupply

All of the posts I made are coming up negative.

*guyfrom7up* Any luck?
*kithso* negative, sir.


Decided to just go ahead and test it on some LED's. Worked ok but i accidentally crossed the wires and now I got nothin. Alas

That sounds weird... Is your multimeter working fine? Test it on a battery or something like that.

Yeah for some reason the new meter read everything negative but an old (really old) meter reads it just fine. I tested some more stuff on it today it seems to work so Im going to call this one a success.

Heres a pic of both the old and new multimeter on the 12v rail. The needle on the old meter is set to test 10v dc because set to 50 it doesnt move really.


You 100% sure you didn't hook the wires up backwards? While power is off, using a continuity meter, check your "ground" with earth ground and the case, they should all register basically 0 ohms, if not then that's not really ground

I did exactly as the ible said, when I checked the case itself for current I got something like a .03 or something similar. Didnt shock me when I touched it at least. Got all the black to ground, all the yellow to 12 and so on. Im fairly certain no wires are crossed or anything like that.