Revo Six NTC shorted thermistor input to 24V, nukes MCU ADC input.
I had encountered an issue with my revo six hotend getting stuck at 150C midprint and didn't resolve after resetting the printer. it would not go above 150C during preheat but got so hot it was smoking and melting its sock, so i thought the thing had failed internally since i hear so many bad things about their quality.
I would like to share the issue and fix in case anyone has a similar issue as i couldn't find details.
I replaced the revo six heatercore but the issue persisted and it too smoked the nozzle until i stopped it.
after probing the T0 / T1/ T2 thermistor I realized T0 impedance to VCC/gnd was much different in T0 than t1/t2 which are identical circuits.
I also somehow overlooked the insulation on the thermistor leads had broken and shorted to input to 24V pwm of the heater and burned through both.
i didn't have my equipment to swap over the passives / diodes or skinny probes to test the individual components, so i was preparing to either order new einsy board or buy the components and swap them.
TBH i am an ee and but really did not have a hunch which component would have blown up. theoretically, everything should have survived.
I am sure I'm not the first person to do this, but an easier (temporary) fix was just to change swap the pindefinitions of Thermistor0/Thermistor1 in the firmware, recompile, and flash the very slightly modified file, only changed the pin defs for TEMP_0 and TEMP_1 (temp_1 / a1 adc input is not in use by default)
#define TEMP_0_PIN 1 //A0 (originally 0 swapped to 1) #define HEATER_1_PIN -1 #define TEMP_1_PIN 0 //A1 (originally 1, swapped to 0)
This allowed a very quick fix and basically just plugged the NTC. in to the spare T1 header and its back up and printing with the original revosix heatercore XD. of course, with some extra electrical tape and fabric tape so it doesn't rub itself raw again
