Did a couple of cuts tonight, was thinking about adding endstops, and I noticed the Arduino board getting warm near where the USB port is. It was hot, but I could still keep my fingers on it, so I’m thinking it had to be under 120F or so.
A spent a few minutes a few feet away while I was soldering wires onto an endstop. Tested my connections with a multimeter to verify that a connection was only made when the stop was pressed down. Success!
If you hold the Arduino/RAMPS package with the USB port pointing up, I plugged my new endstop into the topmost endstop header. It’s not labeled, but some research on the RepRap site indicated this was the most likely candidate for the X minimum endstop. I connect to the Arduino in Repetier host, and start my first test, which consists of closing the endstop and seeing if I can move X-; my reasoning is that the endstop conducts basically no power and thus won’t hurt anything to short for a few seconds. As soon as I press the endstop - literally, the same second - the Arduino disconnects from my computer as though I’d unplugged it. Surprised by this, I release the endstop and look down at the Arduino/RAMPS package… which is now emitting smoke.
I dive for the power strip they’re plugged into - not having wired my emergency stop button fully yet - and turn it off, which cuts power to the power brick that supplies 12V to the RAMPS board. Of course, the Arduino will no longer connect at this point. That’s where I left it about half an hour ago. I suspect I’ll be ordering new logic boards soon, but I wanted to share this in the hopes that somebody else might learn from it. I don’t know what you’d learn though, so if you figure it out, be sure to let me know.
(All my parts were acquired from the Vicious1 site)