How To Use A PC Power Supply With Your 12V 3D Printer
DO NOT WORK ON ANY ELECTRICAL
WHEN IT IS PLUGGED INTO
MAIN POWER! IT'S NOT WORTH
BEING DEAD! DON'T DIE,
UNPLUG THE SUPPLY!
With that out of the way this is a quick guide on how to modify a PC power supply to use with your printer.
Step 1: Pros, Cons And Safety
- These supplies are safe. They have over and under voltage protection, Surge, short circuit, overheat and overload protections as well as a fuse on the mains connections.
- These supplies run cool and quiet with a nice big fan.
- They can provide 12v and 5v, perfect for Octoprint
- They really aren't too expensive. I get mine for about $35 delivered from amazon.com in the USA. Really any PC supply is better than the generic included ones with most machines.
- You gotta rewire it.
- No 24v options.
- Unplug the supply from the wall and wait 30 min before working on it for capacitors to fully discharge.
- Never open any electrical appliance when it is plugged it!
- We are removing all the existing low voltage wires in the supply because on this size unit it's normally about 18AWG wire. This cannot handle the 30 amps of 12v on it's own. Not only that it's ugly to splice them outside the enclosure of the power supply.
Step 2: Tools and Parts Needed
- Soldering Iron
- Wire cutters
- Wire strippers
- XT-60 connectors
- XT-30 connectors
- 12AWG silicone wire for 12v, I like the silicone for ease of use and heat resistance.
- 18AWG silicone wire for 5v
I use this EVGA supply, it's got 360 watts / 30 amps at 12VDC and 17 amps at 5VDC. This is plenty for most printers. It runs my Anet A8 and my Creality CR10 S5.
Step 3: Dig in!
- First open it up. Carefully remove the cover. Now I find it easier to cut all the wires about 6 inches from the board to get them out of the way as well. You don't need them anymore. We are replacing them inside the power supply for a clean look plus the stock wires are not large enough to carry the current the printer will need. Then remove the PCB from the case so you can get to the bottom of it.
- With the bottom exposed start to heat the rest of the wire connections and gently pull them out of the board. Do not remove the green wire that went to the 24 pin plug. This is generally labeled PSON or PSEN.
- Clean up the solder pads so each group has 4 or so open holes clustered together.
- Strip about half an inch off the end of the 12AWG wires. I bundle it into 3 groups to fit it through the board to the other side for solder. This is for the 12V+ and GND
- Gently push the sections through the board to the other side. Make sure they lay only on the pads they are meant to and do not short anything around them.
- Solder the new wire into place!
- Strip back about 1/4 inch of the 18 AWG wire to solder to the 5V pads. Solder into place same way as the big wire.
- Check that the ends are neat and nothing it bridging pads or connections.
- Solder the green wire from PSON to GND. This tells the power supply to turn on the moment it is plugged in.
- Optionally you can connect the green wire to GND through a switch to give you an easy way to turn off the power supply.
- Reassemble the power supply, be sure to plug the fan back in and replace the plastic shield under the PCB.
- Now solder the XT connector on the other ends of the wires. the XT-60 for the 12V and XT-30 for the 5V.
- On the bottom of the power supply I like to put some little rubber stick on feet.
- On the printer side use the other ends of the connectors and some more of the wire to finish running to the board or whatever needs power.
Step 4: Testing and Using it
Test it out
Before you connect it to the printer verify polarity and voltage with a meter. Just to be sure, also make sure it has output. If anything is shorted the supply will not output and will wait in protection mode. To reset the supply unplug it from main power for 2 min then re plug it in.
and be safe, please. Electricity should always be respected.