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Incorrect bed and hot end temperatures

Posted by Stretch 
Incorrect bed and hot end temperatures
September 27, 2017 10:51PM
Hi all,

I wonder if someone can point me in the right direction...

I bought one of the original RS Components Ormerods many years ago and, despite upgrading the firmware, I had endless problems trying to commission the printer. I gave up after the Duet board no longer read the memory card properly.

I recently dug out the printer again and bought a replacement Duet board that arrived with version 1.17E firmware loaded and everything went well except for the temperature control.
Basically neither the bed nor the hotend reach the temperatures reported to Pronterface . I am guessing my early Ormerod requires a different resistance to temperature lookup table than the one in the latest firmware but nowhere can I find a definitive fix for this.

To recap : how do I change the new Duet loaded with 1.17e firmware to give the correct temperatures when connected to old hardware?

Many thanks
Stretch
Cape Town
Re: Incorrect bed and hot end temperatures
September 27, 2017 11:45PM
Check your M305 lines in your Config.g if the R value is R1000 change it to R4700 this is the sense resistor value and was changed for the later boards.
Re: Incorrect bed and hot end temperatures
September 28, 2017 12:28AM
OK thank you Dougal. I will try that.

Huge improvement. A reported 60 deg C bed temp is now measuring at 37 deg C (up from 23) and a reported 110 deg C is now measuring at 78 deg C (up from 57).
I guess I may have to tweak the B and R parameters as well.

Stretch
Re: Incorrect bed and hot end temperatures
September 28, 2017 03:29AM
Yep that's the std symptom of incorrect sense resistors you may also have to adjust your B Values don't touch the R values you can also adjust the S and H values I think they are but you can now also autotune the Heaters go have a look in the Duet3D forums for much more info Duet3D
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