How to modify old CPU PSU into bench power supply?

[NeedsMoreFlux]

I've been looking around the interwebs for information to convert my old CPU power supplies into a bench top power supply.

I've found some places that suggest you use 1x220ohm/10watt resistor on 12v to ground. And 1x100ohm/5watt resistor on the 5v to ground.

Anyone have any experience on these?

And the thin green wire just needs to be touched to ground(thick black wire) if I'm not mistaken(?) Or does I need to keep the switch on?

I made my own air filter for solder fumes, and I will be using it alot, as soon as I get this question figured out.

Thank you all.

[eccerr0r]

Re: How to modify old CPU PSU into bench power supply?

The problem is that there are too many unique power supplies out there to really give a good suggestion on what to do with them. If you don't need voltage or current control, then shorting the green wire to GND on a working PSU will turn it on,and not much more needs to be done.

Some PSUs don't need minimum load. But those that do, that's what the added resistors are doing. Look at the label and see if there's a minimum load, use that current rating and Ohm's law to calculate a resistor that meets that requirement.

[Lloyd6202]

Re: How to modify old CPU PSU into bench power supply?

I just finished building one..I suggest a buck boost board on your 12 v

[Lloyd6202]

Re: How to modify old CPU PSU into bench power supply?

Nothing fantasy but works for everything I need to do

[NeedsMoreFlux]

Re: How to modify old CPU PSU into bench power supply?

HAHAHA, I just shocked the crap out of myself. I was feeling around for high temperature on the PSU after I modified it.

I don't think I even touched the transformer. But it felt like my finger was getting hit by a fan. It took a second to register and pull my hand away.

WTF lol! It has cheap yellow tape around it to insulate it, and my finger was near the top, not the bottom where the solder joints are?!?!?!

Maybe I should coat it in plasti dip...

[stj]

Re: How to modify old CPU PSU into bench power supply?

yea, in california you feel like your finger hit the fan - try that shit in europe and you will think your hand got hit with a hammer!

when you have real mains, you pay more attention to where your fingers are!

[goontron]

Re: How to modify old CPU PSU into bench power supply?

^ Yeah bud, the core floats at PFC voltages.

Like STJ said. Its nothing compared to 200+ volts (277 in my case...)

[goodpsusearch]

Re: How to modify old CPU PSU into bench power supply?

Take at look here:

https://www.badcaps.net/forum/showthread.php?t=32826

[vinceroger69]

Re: How to modify old CPU PSU into bench power supply?

i have a atx supply ive converted into a bench psu im thinking of adding a usb port so i can charge devices now ive read various posts regarding adding a 200 ohm resistor across the data pins as some devices wont charge without it whats your thoughts.