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Thermistor questions!

Posted by GuerillaEngineer 
Thermistor questions!
September 12, 2015 01:04PM
Hey guys, new user. Searched for an answer to this but can't find exactly what I'm looking for. Bought an i3 kit for my first printer. Running Marlin Pronterface. It's built, everything runs endstops work homing works, extruder and hotbed heat up, hotbed reads 31* at ambient (its in my garage), extruder reads 0. I had to replace the heater and the thermistor with this Thermistor. Tested out the board by swapping leads with the hotbed and it registered 31* on extruder ambient temp. I've narrowed it down to either the thermistor or the settings though I've alread replaced the thermistor a 2nd time just in case. I've tried a few different numbers in Marlin from a couple different forum suggestions but I can't figure this one out. Please help!

**Update** Changed temp sensor to 11 as one forum said to look for 3950 in the listed thermistors but it now reads -27* so it's definately a program issue. But now what settings do I need to adjust to get to the correct reading or do I change the sensor?

Edited 1 time(s). Last edit at 09/12/2015 02:28PM by GuerillaEngineer.
Re: Thermistor questions!
September 13, 2015 04:03AM
First check the resistance of the thermistor as is, i.e. leave it on the hot end. If it reads lower than 100 ohms it's broken, if it reads 0 it's shorted, check the leads making contact on the heater block. If it reads much higher than 100k at ambient like above 1 mega ohm.

Now check at which connector it's connected to. Maybe you've connected it to the 2nd extruder connector. Also lookup the connector layout of your board to make sure you're using the correct one.

Check the board you're using in firmware and pay attention to what combination of extruders, bed and fan you have configured.

If it still isn't working check what pin is assigned to the connector using the boards schematic. Look in pins.h if the pin assignment matches.

You can try updating the firmware.
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