Hi, I plugged a 12v DC bench supply into my Atmega2560 with Ramps board. No usb plugged in. Powered through barrel connector. As soon as I turned on the bench power supply - my board smoked. I verified that it as dial to 12v. Not sure if it ruined my ramps board.
Not sure what the problem is - supposed to be able to take 12v. Is it possible that the barrel connector has the wrong polarity or it is simply that I should send 12v to the ATmega and instead power the ramps board?