I have a "classic" home built 3D printer, Arduino Mega, RAMPS 1.4 with Marlin 2.0.
It worked, was put in storage, and now I am trying to get it running again.
During all of the testing phases, the PID autotune, etc., the temperature of the hotend is stable.
When printing, for a few layers (4-5), the temperature is OK, despite the part fan coming on and off. However, after 3-4 mm of printing the temperature just rises and rises and rises, and after 275 °C thermal protection kicks in...
MOSFETs have additional cooling and a fan over them.
I'm out of ideas... Help!!!
My config files and G-code are here
Why do I see a temperature rise on the display? Last time I unplugged the printer and left it on USB power then gave it power again. During USB power temperature was steadily going down, as soon I plugged the main cable it resumed printing and the temperature rising again.
I did another test. 20mm above bed started printing, and got same result. I captured on video entire process Hot end to orbit. Around 2 min 30 sec the show begins.