Hello Forum-Members,
I've built a 3d printer with a ramps 1.4 and repetier firmware on an Arduino Mega.
The porblem is when I heat up the extruder, it works fine until the extruder reaches around 170°C then it gets shut down with the error message heater decoupled.
The strange think is when the heater is turned on it heats up, then at around 90° at the hotend, the heat-bed thinks it also gets heated and its value rises and rises fast and steady, but the bed doesnt heat up in reality just the board thinks so and I didnt told the bed to. Even if the heatbed is not connected to power and a normal 80k resistor is connected as a thermistor the board thinks the heatbeds temperature is rising the same way.
The board lets the heat-bed temperature rise up to 70°C and then it shuts down the hotend with the decoupled message, also the heatbed temp goes down then. I think there is some connection between the heat-bed temperature rising and the hotend geting turned off.
It must be some problem with the firmware, because changing the ramps board didn't change anything.
