I'm running a Ramps 1.4 with Marlin, and a J-head MKV hot end, and my hot end has been working smoothly for a few months now. A couple of days ago I was about halfway through my print, and my hot end started to lose temperature. I tested for a short in the hot end, and proper thermistor readings, and both checked out, making me think my MOSFET burnt out. I ordered a new one, and in the meantime have moved my hot end to the D9 port on the ramps, and changed the pin assignments in the firmware. Everything was working well, until today my D9 MOSFET also burnt out.
I was wondering if anyone knows of anything that would cause both MOSFETs to burn out in a short time. I haven't found much about people overheating MOSFETs, so maybe there is an issue with mine. In the Marlin there is an option to adjust the PWM anywhere from 0-255, and I was thinking maybe I should lower my setting from the default value of 255. Any thoughts would be great, thanks!
