Hi,
I'm working with RepRap X400 and I have following problem: after removing the extruder for cleaning, it won't to show real temperature of the end.
It shows only -20 C, and heating is not controlled.
Any suggestions how to solve this issue?
Hot-end temperature is controlled by a thermister, Ohm the thermister it should measure between 2-20ohms.
Check that the thermister is not shorted to the hot-end, I normally wrap the washer covering the thermister with heat tape then poke a hole in the tape for the securing screw.