Mendel90 build: ATX power supply modifications

Before even receiving my Mendel90 kit I knew that I’d need to prepare a power supply, since Nophead does not include one on kits shipped to the US. I’m pretty particular about power supply quality so I went ahead and got a Corsair CX430M, a very nice ATX supply which is probably overkill for this project. All the same, I’ve had too many experiences in which a bad power supply can mess up a project with¬†difficult to diagnose problems.

Note that there is a very comprehensive guide to making these modifications on the RepRap wiki, as well as some specific steps in Nophead’s assembly instruction pdf.

 

Testing the 12V output by bridging green to ground with a small resistor

 

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I used a 56 ohm resistor here, better than just shorting it

Hacked off the main ATX harness and ignored the additional harness modules

Hacked off the main ATX harness and ignored the additional harness modules

Tied off extra wires (3.3V, extra 5V, power good), so that they'll stay inside the bundle loom

Tied off extra wires (3.3V, extra 5V, power good), so that they’ll stay hidden inside the loom bundle

Used some large heatshrink to close off the main bundle with unneeded wires terminated  inside

Used some large heatshrink to close off the main bundle with unneeded wires terminated inside

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Soldered the PWR ON to ground through a small resistor, then covered the whole thing in heatshrink. Will replace this later if I need some kind of soft power control.

Nophead recommends using all the ground leads, so I soldered them in a neat bundle. Hope it fits into the terminal on the controller board.

Nophead recommends using all the ground leads, so I soldered them in a neat bundle. Hope it fits into the terminal on the controller board. Like my 5-way braid?

Resulting output leads

Resulting output leads

Basically I ended up with the following outputs:

  • +12V (yellow bundle)
  • ground (black bundle)
  • Two extra ground wires, just in case (black)
  • Two +5V wires, for an Arduino etc (red)
  • Standby power wire, just in case (purple)
  • Soldered PWR ON to ground lead (green/black)
  • +3.3V bundle, capped off, again just in case (orange)

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