I had my 3d printer plugged into the wall and went to plug the usb from the arduino into my macbook and when it touched the metal case it sparked and the arduino stopped working. This is the third board I've killed in a couple months but this is the first time I've seen it spark. Ive looked for shorts but cannot find any. If anyone has any idea what could be causing this id love to hear it because I'm stumped. Thanks https://reprap.org/forum/read.php?1,662697,662697#msg-662697 Fri, 10 Jul 2026 22:47:42 -0400 Phorum 5.2.23 https://reprap.org/forum/read.php?1,662697,662916#msg-662916 https://reprap.org/forum/read.php?1,662697,662916#msg-662916
Any voltage (5, 12, 24, 110, 220-240, 440 volts) just loves to be grounded. IE go to earth aka it says "take the path of least resistance" upon it travels around the circuit

I know of a project which "took out and killed 3 Arduino Megas" because the live wire of the 15v power supply to the stepper motors touched the metal frame of the project.]]> orictosh General Wed, 11 May 2016 22:49:06 -0400 https://reprap.org/forum/read.php?1,662697,662903#msg-662903 https://reprap.org/forum/read.php?1,662697,662903#msg-662903 Andrey_SSh General Wed, 11 May 2016 20:56:02 -0400 https://reprap.org/forum/read.php?1,662697,662795#msg-662795 https://reprap.org/forum/read.php?1,662697,662795#msg-662795 daboomafoo General Wed, 11 May 2016 13:45:41 -0400 https://reprap.org/forum/read.php?1,662697,662766#msg-662766 https://reprap.org/forum/read.php?1,662697,662766#msg-662766
1. Check that the wire connecting the negative 12V output terminal of the PSU to the power input of the electronics board is securely connected at both ends.

2. Make sure that the AC mains cable connecting the PSU to the mains includes a ground wire.

3. Connect the negative 12V output terminal of the PSU to the ground terminal (in ATX PSUs this is normally done already inside the PSU). This means that any leakage (e.g. due to the capacitance of the transformer) passes to local mains ground instead of through the USB cable.

4. Power the PSU and the macbook, and nothing else, from the same AC mains distribution block.

Ground voltage differences between 3D printers and PCs are a frequent source of problems when a USB connection is used. An Ethernet connection avoids the problem. So does running the laptop off its battery while it is connected to the printer..]]> dc42 General Wed, 11 May 2016 12:53:48 -0400 https://reprap.org/forum/read.php?1,662697,662720#msg-662720 https://reprap.org/forum/read.php?1,662697,662720#msg-662720 You can measure the difference with a voltmeter.

Serach a better PSU for your printer ...]]> VDX General Wed, 11 May 2016 11:05:37 -0400 https://reprap.org/forum/read.php?1,662697,662697#msg-662697 https://reprap.org/forum/read.php?1,662697,662697#msg-662697 Thanks]]> daboomafoo General Wed, 11 May 2016 10:02:30 -0400