BetaArchive
https://www.betaarchive.com/forum/

Converting a ATX PSU to a Lab PSU [Soldering, external link]
https://www.betaarchive.com/forum/viewtopic.php?f=39&t=8191
Page 1 of 1

Author:  longview [ Thu Jun 11, 2009 1:17 pm ]
Post subject:  Converting a ATX PSU to a Lab PSU [Soldering, external link]

Since a lot of you guys probably have lots of old computers and PSUs, I though you might like this simple guide for converting ATX PSUs into regulated lab power-supplies!

Image
This is my attempt, took about 3 hours at school to do.

Link to guide (WikiHow)

More technical details

In my version I moved the 120mm fan to the outside to make room for extra wires and future expansion, I used a 7W 8,7 Ohm resistor over the 5V rail and cable ties, since it's actively cooled there's no real risk it'll overheat.

Specs (in theory) for my 350W:
3,3V - 22A (72W)
5V - 21A (105 W)
12V1 - 10A (120W)
12V2 - 15A (180W)
-12V - 0.3A (~4W)
Notes: the load on the 3,3 and 5V rail must not exceed 130W in total

Author:  benjmole [ Thu Jun 11, 2009 3:13 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

You did this at school? :o I never learned anything like that at school. Haha.
Maybe because my school sucked, but thats besides the point. ^^

Author:  Andy [ Thu Jun 11, 2009 3:16 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

He did it at school because they had the equipment to do it (soldering iron etc). It wasn't a school project.

Author:  benjmole [ Thu Jun 11, 2009 3:20 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

Makes sense. Still better than my school though, they thought Vinegar and Bicarbonate of Soda was GCSE level Chemistry. Hah.

Author:  longview [ Thu Jun 11, 2009 4:01 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

Actually I had a day off today, I came in specifically to do this.

I even got the PSU from school, we threw out a lot of old computer stuff earlier this year.

Author:  someone153 [ Thu Jun 11, 2009 9:20 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

I actually did this too about a month ago. I used a generic PSU that came with my old Dell. I believe it was about 250 watts. I'll take pictures and put them up in a few hours, when I get home.

Author:  longview [ Thu Jun 11, 2009 9:34 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

Hmm, interesting. I'd read Dell supplies often use non-standard colour codes, did you run into any problems with that?

Author:  someone153 [ Fri Jun 12, 2009 4:05 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

I actually did. The 5V and 3.3V on the motherboard power connector were strange colors. I just went online and found the wiring guide for the connector to the motherboard. Another thing that went wrong was I wanted to have a positive and negative 5V line, but the Dell power supply did not have a negative 5V line at all. The place on the connector did not have a wire going into it. So I just settled for 3.3V, 5V, postive 12V, and negative 12V.

And as promised, a picture:
Image

Note: The PSU case is grounded, so that is why there is a connector on the case, but the black connector thingy on top is also a ground.

Author:  longview [ Fri Jun 12, 2009 5:01 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

Nice work!

As mentioned in one of the links I posted the -5V rail was removed from the ATX PSU spec years ago, an older supply might have it though.

If you really want a -5V you could install a L7905 and drive it off the -12V rail, it shouldn't be a problem installing and cooling it.

Author:  someone153 [ Fri Jun 12, 2009 9:28 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

Thanks! The PSU was around 5 years old so I thought it might still have the -5V line, but unfortunately it did not. I usually just use a voltage divider to get the exact voltage I need anyways. The only other thing I wish I had done was put an on/off light because the PSU is so darn quiet sometimes I can not tell if it is on or off.

Author:  nookupeous [ Mon Aug 17, 2009 10:28 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

I've seen numerous tutorials for this on the net, but this is one of the most complete. Do you think I could do this with a 100W MicroATX PSU?

Author:  Andy [ Mon Aug 17, 2009 10:29 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

nookupeous wrote:
I've seen numerous tutorials for this on the net, but this is one of the most complete. Do you think I could do this with a 100W MicroATX PSU?


You can normally do this with any PSU.

Author:  nookupeous [ Tue Aug 18, 2009 4:41 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

Andy wrote:
nookupeous wrote:
I've seen numerous tutorials for this on the net, but this is one of the most complete. Do you think I could do this with a 100W MicroATX PSU?


You can normally do this with any PSU.


Cool, thanks for the help. Now, just to clear something up, the only real difference between ATX and microATX is the size right? Like all the wires on the plugs and such are the same.

Author:  Andy [ Tue Aug 18, 2009 4:42 pm ]
Post subject:  Re: Converting a ATX PSU to a Lab PSU [Soldering, external link]

I'm pretty certain that's correct, yes.

Page 1 of 1 All times are UTC [ DST ]
Powered by phpBB © 2000, 2002, 2005, 2007 phpBB Group
http://www.phpbb.com/