Was trying to replace a power resistor in an old hot end, and something fried after heating a few degrees. I presumed the power resistor, but I then found that the Arduino board was no longer detected by Windows. It had the solid yellow light on power up. I’ve had this before, so I know this means dead Arduino.
So I plugged in a replacement new Arduino, with a replacement ramps 1.4 board, located the step sticks from before, and fed the 12v power in. Instantly heard the same crackling noise and saw the same blue smoke as when the first boards fried.
I guess the stepsticks were probably shorting out from damage the first time around, because the other components in the system were new at that point.
I’ve ordered a new Arduino, Ramps board, and set of stepper drivers, but for now I’m questioning my testing process as I don’t want to fry any more stuff.
Sanity check: I plug a new ramps board into a new Arduino with new stepper drivers on and power it up. If it doesn’t fry, that means the stepper drivers were to blame for the second frying episode. If it fries again, I don’t know what the hell to do next! My PSU is putting out 12v and seems fine.