Arduino shorts out when project mounted in frame

Other Hardware Device Hacking
1

Hey,

So was converting my G27 pedals to work standalone using a DCCduino Nano / Arduino Nano, to use it via USB, with the following wiring:

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Everything worked great when outside the frame, but once I mounted it in the frame and connected the Arduino with my computer, it shut off and I smelled fried electronics.

It ended up being this component which broke: (Img)

Luckily I had an Arduino Uno. After some poking around, I found that connecting the 5V with the pedals mounted in the frame somehow shorted it to ground. Just the 5V though, none of the other signal wires or ground caused issues. Just 5V to pin 1 on the D9 connector.

While I solved this using some DIY rubber washers to electrically insulate the pedal set from the mounting plate, I'm still curious how this could be caused.

The pedal sets' ground is shared with its mounting points - but should that cause the 5V to short with ground? It works fine outside the frame so I doubt it's anything internal in the pedal set.

Other stuff bolted to the frame are a steering wheel base with its' own 24V supply, a monitor with a 230V plug and a shifter, powered with USB. Everything is connected to a computer with USB and DisplayPort.

The computer didn't have the same mains ground as the monitor and wheel base supply due to the house having no grounded plugs, but after re-wiring the mains stuff so they share a common ground, I still got the short.

Has anyone ever seen something like this? Took me most of the evening until I gave up and went for the insulation solution.

2

With all that building you have done, you MUST have a DVM, digital volt Ohm meter, laying around. Check the resistance between the frame and your Arduino pins and see if you have a short Before you make connections.
You likely have a short back through all the other stuff connected.

3

Hi,
With both parts separated, use you DMM to measure the DC and if any AC volts between them.

Thanks.. Tom... :grinning: :+1: :coffee: :australia:

4

Well, I'm stupid for following random diagrams on the internet without checking how things are myself. The GND and +5V were swapped, as I measured +5V between the pedal "ground" and the frame. After swapping GND and 5V, things are fine again and I can connect both GNDs together without issues. Signal seems to be much less noisy too.

Thanks, mystery solved!

Edit:
I also now spotted the diagram which I blindly followed clearly connects the Arduino 5V with the clearly GND marked pins. Man I'm stupid.

As a warning, I followed the resources in this YouTube video without much critical thinking.