Thermistor reading high temperatures

Hello all,
I bought myself a folger tech 2020 i3 prusa aluminum 3d printer kit and just finished building and configuring it. I followed the building and consiguring guides rev B. When my printer was ready to print I noticed that the repetier software was giving weird temperature readings of 189 C for the heated bed and extruder. The heated bed stays at 189 without changing and the extruder reads from 188 and 189 C. That's at room temperature. When I activate the extruder, it starts getting hot but the software will keep reading the same. I double checked the wiring already and it seems to be right. The fact that I'm getting this readings means the thermistors are responding in some way.
Any suggestion or similar cases?

Could be a short on the thermistor. If you have a multimeter disconnect the thermistor and read the resistance at room temperature it should be around 100kOhm for most thermistors. If it gives a very high value or reads 0 it is damaged/shorted.

Put the thermistor in your hand and make sure the resistance reduces as it warms up.

They are very fragile and delicate it's alway worth spending $5 on a pack of 5 spare thermistors make sure you make a note of what type they are so you can set this in your firmware.

Edited 2 time(s). Last edit at 05/15/2016 08:36AM by DjDemonD.

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Thanks for the help. The thermistors are in good shape. I started messing with the firmware and got them to work, but after some print the heated bed started giving the same temp values as the hot end. Whenever I heat up the bed nothing happens but when I heat up the hot end both the heated bed and the hot end readings start rising. I switched the thermistor connections and now I'm getting the heated bed readings on both. So the connection T1 is the one that is not working now.

Edited 1 time(s). Last edit at 05/18/2016 01:44AM by leomireles007.

Something is really wrong here. Reflash the firmware. you should never have T0 and T1 Reading the same reading

Maybe the pins file has both t1 and t0 pins allocated to the hot end?

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Simon Khoury

Co-founder of [www.precisionpiezo.co.uk] Accurate, repeatable, versatile Z-Probes
Published:Inventions

Just a thought, I have built a few Folger kits and I had a similar issue with one (of 5) of the builds. In this case the solution was a new RAMPS board. If you have a spare RAMPS I would try that as a troubleshooting step.

In my case this solved it and I didn’t do a lot of additional troubleshooting after I solved the issue with the new board. Hope this is helpful in some way.

How do I fix the pins file? I took a look at it but I can barely understand it. If I can't fix I'll end up getting another RAMPS

Edited 1 time(s). Last edit at 05/18/2016 12:34PM by leomireles007.