ATX PSU to 12 volts for a 3D printer

batatas · September 8, 2019

Hi i am trying to mod my 3d printer and i was thinking on using an atx PSU to power it.

But im not in the mood to cut the wires of the psu so i would like to know if there is a pcb i can buy to connect the connectors for the psu and make it a single 12 volts rail.

If there are none i will have to make one myself but i would like to know if someone knows of something.

Thanks fo the help.

airdeano · September 8, 2019

if trying to adapt a ATX PSU to a 3d printer you'll need to consider these:

Quote

What to look for in an ATX PSU for your RepRap project

There are scores of ATX PSUs that will fit within any power range, from various brands and in various lines. To help with your choice of ATX PSU for your RepRap project, here is a short list of desirable features:

Exceeds the previously calculated (see above) minimum power requirements by 30% or more on its 12V rail(s).

Has PFC. Preferably active PFC.

Has a temperature controlled fan, 12cm (good) or 14cm (better).

Has a guaranteed efficiency rating. Nowadays (2014) manufacturers have standardized over some efficiency labels such as Bronze, Silver, Gold and Platinum. Bronze is more than good enough for RepRap use.

Has a Power On/Off switch.

"Haswell compatibility" (explained below).

Comes from a generally recognized manufacturer and has received positive reviews from hobbyist websites (such as those mentioned above).

Once you have decided on a realistic budget, it should be easy to find and purchase online an adequate ATX PSU for your RepRap project with all the desirable features listed above. One tip: don't even waste time considering ATX PSUs at the "bottom of the heap" i.e. those $20 noname ATX PSUs you can find on eBay, or some old second hand ATX PSU. For a few extra dollars or euros you can certainly find much better quality stuff, new in the box, and that's what you'll want to use in your RepRap project.

source: https://reprap.org/wiki/Choosing_a_Power_Supply_for_your_RepRap

as for a pre-done PCB, prolly in aliexpress, but those may not have express connections/terminations (you'll prolly have to adapt).

emosun · September 8, 2019

you can get an always on plug for the 24 pin connector , then just pull power from the 12v lines via pci-e and cpu connectors

mariushm · September 8, 2019

The 24 pin ATX connector has only 2 12v wires, so you'd be limited to around 200 watts.

Pointless to use that for anything. You're better off using the pci-e 6 pin connectors.

You can get one of these to make it easy to start the power supply : https://www.ebay.com/itm/24-Pin-Female-ATX-PSU-Power-Supply-Starter-Tester-Start-Up-Jumper-ON-OFF-Switch/323153454892

You can buy some pci-e extension cables and simply cut one of the connectors, and you end up with multiple pairs of ground and 12v wires. If you buy a single rail power supply, you can combine all 12v together without any worry.

Here's loads of such cables: https://www.newegg.com/p/pl?N=8000&d=pci-e 8 pin extension cable&Order=PRICE

Yellow wires are 12v , black wires are ground .. easy peasy.

May want to not buy the cheapest, as those usually have AWG20 wires which are thinner and don't carry as much current as thicker AWG16 or AWG18 wires.

Or you know... you could just open the power supply and desolder the existing wires if the psu is not modular, and solder your own wires... use AWG16 or AWG18 wires. When you want to reuse the psu, you can solder the connectors back to the psu.