I replaced my hotend with a e3d kit which included a 104GT2 thermistor. When I started the printer back up it showed 360c for the extruder temp. I sent the command to switch the thermistor type and it jumped to 700c. I’m pretty sure it’s a board issue because there is no change in reading even if I completely disconnect the thermistor. It does the same thing now with the original thermistor. Both have the correct resistance. I’ve been searching all day but I haven’t found anyone reporting a similar problem. Does anyone have a suggestion to try before I replace the controller?
Uhh, I had the same thing happen to me when I was installing the e3d clone hot end. Frst time it was due to forgetting to plug the thermistor back in. So there is definitely no voltage or no communication with thermistor. I think u should still be able to check for continuity of both of your thermistors and if good firmware settings (may be reset to defaults, update…) Second time it happened is when I shorted the board and a tiny chip (bottom left if u look from sd card side) was very hot. Seems like you would need a different board or printer… In case u were trying to get better results with ABS on it, I can share that after 3 months and 2 MP Minis I understood that it is best with original hot end and PLA. I recently got MP Maker Select v2 and this thing does ABS like butter on a toast, if you are in to that sorta thing 
That’s the max temp that thermister can report, and you are seeing it because there is a short
between the wires or leads. (If it read zero, that would indicate a break one of the wires or
connectors.)
The short is most likely where the thermister is mounted to the heat block. Take a close
look, you probably have the two leads touching each other.
I verified that everything was plugged in correctly after the hotend swap. Both thermistors test good and I did a firmware reload. I’m not sure how I could have shorted anything on the board but apparently that is what happened. I was swapping because I was too trusting and left a print going overnight. It popped loose about halfway through and the rest of the PLA ended up on the hotend. I already had the e3d so I decided to just change them out.
I see the same temp even when the thermistor is unplugged so the short must be on the controller.
Makes sense. Good luck with it!
By-the-way, there’s a large group of Monoprice Mini users over on Facebook. Among the files they maintain is a list of replacement parts and where to find them.
Thanks! I’m checking it out now.
