3D printing and other software curiosities
by Clinton Freeman

How do you convert an ATX power supply to use with RAMPS 1.4?

23 Feb 2013

Question

The RAMPS 1.4 board comes with a 4-pin screw terminal for power, how can I convert my ATX power supply to work with my RAMPS board?

Answer

The first step is to make sure your ATX power supply has enough juice to power your printer. A heated build platform sucks down loads of power, and this article will step you over what to look for when shopping around for ATX power supplies to power a RepRap.

OK, so before we get started. Make sure the power supply is off and unplugged from the wall socket. You will also want to check the sticker on the side of your ATX power supply again to work out what coloured wires (it will be yellow, with maybe a stripe on it) that have enough current to run your printer. This will be one of the 4pin 12 volt connectors.

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Cut the connector off the power supply (cut all four wires), and strip them back to expose a bit of bare wire. I also like to ’tin’ the exposed wires to make the connection more durable. With the wire stripped back and tinned, it is easy to attach to the screw terminal. But be careful with the polarity! If you get the wires back to front, you will fry your RAMPS board. The yellow wires go to positive (+) and black always goes to ground (-).

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Now you might be thinking “Whoo! All done!” Well almost. If you plugged everything in, you will notice that power supply fan isn’t spinning and nothing is on. This is because ATX power supplies have a special green ‘power on’ wire that acts as an on/off switch (this little green wire is what allows your computer to turn itself off when you hit shut down in your favourite operating system). Essentially, our printer hasn’t told the ATX power supply to turn on. It is pretty easy to trick an ATX power supply into turning on, by shorting the green ‘power on’ wire. I usually just get a breadboard jumper wire and bridge the green socket with a black one. Alternatively, you might want to cut and solder the green wire with a black ground wire.

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