Temperature Problem

Hello everyone,

I've just finished to build my Omerod few days ago and keep having problems with the heating i guess. This is what i get with Pronterface (see 273.PNG attached).

I've read that it could be my sensors which are not connected but i have double checked several times, i have rewired the bed sensor everything seem perfect and i still get what i get on the screenshot.

I've also attached the pronterface log which i don't really know what it means.

Thanks per advance for your answers

Have you tried measuring resistance across the thermistor wires (down at the connector) with a multimeter? You should get around 90-100kΩ at room temperature.

It does indeed most likely mean that the sensors are not connected. However as both sensors are reading -273 itbis just possible that you have a faulty Duet board that is failing to provide +3.3V to tge thermistor circuit.

It is very difficult to get good crimp connections to the fine wires of the bed thermistor. I recommend soldering them instead. I have also had problems getting a good thermistor connection through the 6 pin hot end connector. I now use a different connector.

I suggest you disconnect the heated bed connector and hot end thermistor connector at the Duet and use a multimeter to measure their resistances from the Duet ends of the cables. You should read about 10k for the bed thermistor and 100k for the hot end thermistor.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks both of you for your answers !

i will try your solutions and let you know really soon

I get the same problem. It does not see the head heater. I have found that warming it a little with a heat gun and then sending M562P1 and setting the temp.

Hi IBDunne, it sounds as though the ADC on your Duet may be out of tolerance. I believe RepRapPro is replacing Duet boards that have this problem under warranty. Otherwise, using the M305 command supported by my firmware fork to adjust the H parameter may solve it, or you can add a resistor of a few hundred Kohms in parallel with the thermistor.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Hello,

Could you give me more details because i don't really know where should take the measurements ?

After trying again i got this on pronterface : T:12.6 B:-273.1, i guess is because i had some contact default on the thermistor wire but i still have one problem somewhere :/

Thanks per advance !

Edited 1 time(s). Last edit at 09/18/2014 12:04PM by Michmich229.

For the bed thermistor, unplug the ribbon cable connector from the Duet. Then measure between the 2 middle pins of the connector. Sorry I can't post a photo because I'm away from my Ormerod. For the hot end thermistor, unplug the hot end loom connector from the Duet and measure between the blue and green wires.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

As soon as i get a soldering iron and a multimeter, i will let you know if i've fixed my problem.

I've soldered the crimp of the bed thermistor and then measure the resistance.

i get 100k for the hot end thermistor and 8.7k for the bed thermistor, is that okay ?

The hot end thermistor is supposed to be 100K @ 25C and the bed thermistor is supposed to be 10K @ 25C. So those values are both reasonable. If you are certain that you have them correctly connected to the Duet, try warming the hot end with a hair dryer. Then press the reset button on the Duet (NOT the erase button) to restart it and clear the temperature fault; or send M562P1 to just clear the temperature fault. If it then reads a more reasonable temperature, then I think we can conclude that the ADC in the microcontroller on the Duet board is outside the tolerance that the design allows for.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I've just tried what you said, and i get T:55.2 B:-273.1 and i'm pretty sure it's correctly connected :/

So you are saying the hot end reads sensibly when you warm it with a hair dryer, but reads -273C when the hot end is at room temperature. If your room temperature is reasonable (say 15C or higher), then I think we can conclude that the ADC on your Duet is not within the tolerance that the design allows for, and you should ask RepRapPro for a replacement.

I haven't previously heard of the bed thermistor being so far out of tolerance that it reads -273C when correctly connected, so I still suspect that it is not connected correctly. Where did you measure the resistance? It's also possible that you have a fault on the Duet board.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

No on the Hot end Thermistor everything is fine i guess because from this post :

Quote
Michmich229
Hello,

Could you give me more details because i don't really know where should take the measurements ?

After trying again i got this on pronterface : T:12.6 B:-273.1, i guess is because i had some contact default on the thermistor wire but i still have one problem somewhere :/

Thanks per advance !

i had a correct temperature but for the bed thermistor, i've always had -273.1.

I took the measurements as shown here (Picture too large) , i unplugged the wires to do the measurement of course.

Thanks per advance for your help !

Sorry, I misunderstood about the hot end reading. It sounds to me that you have a short to ground on that Duet ADC input for the bed thermistor. I recall someone else having a similar problem, although in their case it was the Z probe ADC input that was shorted to ground.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

i'm afraid i don't really get it, what should i fix in that case ?

I suggest you email support at reprappro.com and see if they will replace your Duet board.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

Thanks for your help guys !

I've been discussing with RepRap support and it turns out that the cable 13 on my ribbon cable didn't have continuity, i changed it, soldered it directly on the bed thermistor (I'm crazy right ) and now it's working well