Power Supply hookup

[jeffathompson]

I am trying to use an old PC power supply to run my Grinch Boards. I can't seem to figure where to get power. I have the supply completely out and can see where the black, red, orange and yellow wires go into the board. Black appears ground. Red is marked 5+ Yellow 12+ and Orange 3.3+. There also is one Grey, one White, one Green and one Purple. I am assuming that somehow this power supply was originally turned on at the mother board but what do I jump or hookup to turn the 5, 12 & 3.3 on.

[rstehle]

The Green wire is generaly the Power On. Just attach it to one of the black ground wires and you should be good to go.
Here is a link you can reference: http://web2.murraystate.edu/andy.batts/ps/POWERSUPPLY.HTM

[jeffathompson]

The Green wire is generaly the Power On. Just attach it to one of the black ground wires and you should be good to go.
Here is a link you can reference: http://web2.murraystate.edu/andy.batts/ps/POWERSUPPLY.HTM

Green it is. Jumped green to ground and all other leads operate as advertized

Thanks

[NogginBoink]

Note that according to various websites you must put some minimum load on the 5V rail for the power supply to remain stable. I'm no expert, but that's what folks say...

[jeffathompson]

Note that according to various websites you must put some minimum load on the 5V rail for the power supply to remain stable. I'm no expert, but that's what folks say...

Would the fan that starts when I power it up be enough?

[omzig]

Would the fan that starts when I power it up be enough?The fan is 12V.

[NogginBoink]

A 10W 10 ohm resistor is recommended on at least one site.

See http://www.wikihow.com/Convert-a-Computer-ATX-Power-Supply-to-a-Lab-Power-Supply for details.

[Macrosill]

I did the mod using the link posted by NogginBoink and it works great. Powered my Ren64s last year flawlessly.

[aussiephil]

Jeff and all

I have made a small PCB that along with some parts from Mouser allows you to just plug in your power supply and have the voltages available via standard terminal blocks.

This is a Home Etch board and i have the PDF's available.

Regards Load resistors..
I have found that grounding the power wire (green one) will on all the new ATX supplies i have used over the last few years will turn the supply on with no load required.
However
voltages of the outputs will be off by a few tenths of a volt until a small load is applied to the five volt rail.
this load may be the circuit you are suppling 5v too.
If your using the supply to run 12v to other equipment so it can regulate it to 5v then any small variation due to no load resistor is irrelevant and the load resistor can be left off.

ATX power supplies are becoming remarkable stable at next to no current due to the low power requirments of modern computers in sleep modes.

any one who is interested in the ATX Power Adapter please pm me for more details
AussiePhil

[Wayne J]

Phil, that is a neato board, I would love to see the file. :)
Also, where did the terminals come from?

[LDA]

Phil,

Mine arrived today. Cannot wait to try it out. Cant do so for a couple of days as I am not at home.
Les

[aussiephil]

Phil, that is a neato board, I would love to see the file. :)
Also, where did the terminals come from?

Wayne

The Terminals are all available from Mouser - took a little bit to track down that correct parts though :)
The BOM can be found here
http://www.xlcbom.incanberra.biz/pdetail.php?id=5&name=ATXPAv2

I've sent a PM about the PDF's

Cheers
Phil

[aussiephil]

Phil,

Mine arrived today. Cannot wait to try it out. Cant do so for a couple of days as I am not at home.
Les

Les

Glad it arrived. I didn't get a chance to label the outputs i'll send you the component overlay.

Cheers
Phil

[rstehle]

Just an F.Y.I., Molex has a free sample program like Allegro. I recently was able to get some free samples of plugs directly from them.

[deplanche]

I ordered a power supply off e-bay, that had Molex connections, so I was thinking the free samples may have been the way to go. However, I was cautioned that you need a special tool that can be expensive to use.(http://www.doityourselfchristmas.com/forums/showpost.php?p=28010&postcount=6). Remember, this is no such thing as a free lunch... just free chips from Allegro. :)

[aussiephil]

No special tools to build the adapter board - the outputs are screw terminal blocks.

Cheers
Phil

[rlilly]

I ordered a power supply off e-bay, that had Molex connections, so I was thinking the free samples may have been the way to go. However, I was cautioned that you need a special tool that can be expensive to use.(http://www.doityourselfchristmas.com/forums/showpost.php?p=28010&postcount=6). Remember, this is no such thing as a free lunch... just free chips from Allegro. :)

While Molex would love to sell you a crimping tool, I just soldered directly to the pins. They insert fine into the plug without crimping.

For those wanting the Mouser part numbers for the pin and plug, Kevin added it to his site under Power Supply. HERE (http://kevincook.net/Hobbies/Electronics/Lights/PowerSupply/index.htm)

[rstehle]

Same here, just soldered the wires to the pins and inserted in to the plug. No special tool necessary.

[aussiephil]

OK

for those that have PM'ed me already thankyou for the interest and my apologies if you cannot get to the pdfs in the thread at DLA.

I have now attached the pdf's here to save issues for everyone.

the link to the BOM is below
http://www.xlcbom.incanberra.biz/pdetail.php?id=5&name=ATXPAv2

Cheers
aussiephil

[ppohlman]

A 10W 10 ohm resistor is recommended on at least one site.
Hey NogginBoink -

Would a 25W 1KOhm resistor work instead of the 10W 10 ohm that you mentioned?

[aussiephil]

Hey NogginBoink -

Would a 25W 1KOhm resistor work instead of the 10W 10 ohm that you mentioned?


No

a 1k resistor will put a 5ma load on the 5v line - must likely irrelevant for the purposes of generating enough current on the switch mode feedback resistor.

Now without schematics etc of the PSU's and data sheets for the IC's used it all becomes guesswork.
Most of the data you currently find for PSU mods is from the original AT days that have been adapted to the newer ATX designs.

if you wish to stabilise the voltage (and this is not really needed these days) then i would start with a 50 ohm 1W resistor. This will put a 100mA load on the PSU and have a power (heat) output of 500mW.

aussiephil

[rstehle]

One site mentioned that if you always operate your PS under a load (i.e. hooked up to a Ren 16, etc.) then the resistor is not needed.

[jeffathompson]

This would probably work.

http://www.allelectronics.com/make-a-store/item/9-12/9-OHM-12-WATT-CERAMIC/-/1.html

But it is a lot easier to just buy this

http://www.allelectronics.com/make-a-store/item/PS-148/POWER-SUPPLY-5.1V/12A-12V/2.5A-12V/2.5A/-/1.html

Or you could save $1.00 and buy this

http://www.allelectronics.com/make-a-store/item/PS-637/5V/8A-3.3V/4A-2.5V/2A-POWER-SUPPLY/-/1.html

I think that's easier even though this is a DIY board

Ok, try the links now. (hope these work)

[WWNF911]

This would probably work.

I think this would work

But it is a lot easier to just buy this

http://this one works

Or you could save $1.00 and buy this

this one

I think that's easier even though this is a DIY board

3 strikes and you're out!

Sorry Jeff, but the links never made it.

[omzig]

I think he was being sarcastic.

[WWNF911]

Not my day. :(

Thats what I get for trying to follow things when I should be working.

[jeffathompson]

Not my day. :(

Thats what I get for trying to follow things when I should be working.

Got'em up and working now.