I've just fitted a new J Head hot end with a NTC3950 thermistor.

3D Printing
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1

I’ve just fitted a new J Head hot end with a NTC3950 thermistor. When I first ran Repetier at room temperature, it showed the temperature as around 340°C. No problem I thought, I need to set the firmware to Thermistor no. 11. So I made the changes in configuration.h and up loaded it. Now the room temperature heated block is showing at 830°C.

Any Suggestions what I am doing wrong?

2

looks like a short cut to me, maybe the contacts of the thermistor are touching each other or the heating block? The 340°C seem familiar to me, had this problem once :slight_smile:

3

Thanks for the suggestion. It isn’t a short it is a break. The hotend came pre assembled, so I wasn’t expecting a problem there, but when I peeled the capton tape off it one of the wires wasn’t connected.

It’s a bit weird, with a Negative Temperature Coefficient (NTC) thermistor, I would have expected it to return a near zero temperature at infinite resistance.