New E3D V6 Thermistor troubles

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ExplodedZombie
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New E3D V6 Thermistor troubles

Post by ExplodedZombie » Sat Jan 14, 2017 8:11 pm

Hello folks,

I recently purchased the new upgrade heater block and thermistor (cartridge) to replace my seemingly useless M3 Stud Thermistor. I set the Sensor_Type to 8 (Repetier) and the thermistor constantly reports around 6.5-7.5 degrees C lower than the heat bed. I measured the temperature and the heat bed is correct. After running the PID Tuning and putting the values directly in the Configuration.h, the temperature seemed better. Then I turned the machine off and back on and it's super low again. Is there a setting I'm missing? Maybe the sensor is just damaged? I didn't over-tighten or anything. I followed the E3D guide closely, but am still having issues. I'm using Repetier 0.92.2, I believe.

ExplodedZombie
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Re: New E3D V6 Thermistor troubles

Post by ExplodedZombie » Sun Jan 15, 2017 8:51 am

One possible issue, would love to hear thoughts: Instead of rerunning the wire for the thermistor, I just moved the JST for the original wire all the way to the top of the machine, so now I'm running 2 different wires for the thermistor, with a total of 2 JST connections. Would that cause issues with the resistance and initial temp readings?

Polygonhell
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Re: New E3D V6 Thermistor troubles

Post by Polygonhell » Sun Jan 15, 2017 1:07 pm

All my E3D thermistors read high, but usually only at printing temperatures, I just fiddle with the firmware settings until they match what I'm measuring.
The fact it's reading low at room temperature, might be indicative of a wiring issue, but your wiring would have to be pretty terrible to add enough resistance to significantly change the reading. It's easy enough to check with a meter. You should see 100KOhms at ~20C (room temperature).

ExplodedZombie
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Re: New E3D V6 Thermistor troubles

Post by ExplodedZombie » Sun Jan 15, 2017 2:31 pm

Thanks for the reply. The wiring starts from the board with the original white thermistor wires, at the top of the printer there is a JST where it changes to red/black wires that came with the NEW thermistor, then there is a JST-like connection at the hot end for a quick change. Previously it was just the white wires and read just fine with the old thermistor at room temp.

Ok. I will attempt reading the resistance but fair warning, I don't really know what I'm doing. I have a digital meter but not sure how to use it correctly. Youtube, here I come.

ExplodedZombie
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Re: New E3D V6 Thermistor troubles

Post by ExplodedZombie » Tue Jan 17, 2017 9:59 pm

Okay I used my multimeter on the thermistor itself. I set it to 200k because the next lowest was 20k and that had 0 result anyways. Set to 200k, the multimeter read 180. That doesn't seem right. So I'll figure out what I'm doing wrong and check again.

Polygonhell
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Re: New E3D V6 Thermistor troubles

Post by Polygonhell » Tue Jan 17, 2017 11:14 pm

I assume you disconnected it from the board to test it, you can't get a valid reading with it plugged in.
If it really is reading that high, there is either something wrong with the thermistor or the wiring. I'd start by measuring at the last connector and then measure each of the plugs.

ExplodedZombie
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Re: New E3D V6 Thermistor troubles

Post by ExplodedZombie » Tue Jan 17, 2017 11:44 pm

Yeah I disconnected it and measured it at the plug connected directly to the thermistor.

To be very specific, it's this thermistor: http://e3d-online.com/Thermistor-Cartridge

It came assembled like that so I just touched one lead in each connection and 180 is what I got. Could be doing the multimeter part wrong though. Will try a few more times.

Polygonhell
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Re: New E3D V6 Thermistor troubles

Post by Polygonhell » Wed Jan 18, 2017 1:33 am

It should be 100KOhms at 25C, it will be slightly higher at lower temperatures, but not 80KOhms.
You might want to contact E3D support, you can damage them by over tightening the set screw, but they usually just fail.
Just make sure you have a good solid connection between the probes and the wires, there really isn't much more to measuring resistance with a multimeter, assuming it doesn't have a flat battery.

ExplodedZombie
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Re: New E3D V6 Thermistor troubles

Post by ExplodedZombie » Wed Jan 18, 2017 1:41 pm

Will do thanks very much for your continued help!

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