Heated Bed Issues

[tpulti-bt 0]

Hi there,

we have once again issues with our heated bed. We use a 100k thermistor to measure its temperature and get the max-temp-triggered-error every time. To eliminate soldering problems we connected the thermistor directly to the board, still receiving the same error. Are there any glitches concerning the firmware?

many thanks and best regards

tpulti-bt

edit: funnily enough we changed the firmware setting to epcos 100k with the result that we measure 0 degrees constantly and always get 19V output at the heated bed connector.

[phanc60844 0]

did you solder the resistor to the board to allow the thermistor to be read?

[tpulti-bt 0]

Yes. A 4.7k resistor

[Daid 304]

Which version of the firmware are you using?

[tpulti-bt 0]

The one generated by this site:

http://daid.eu/~daid/marlin_build/

 

[Daid 304]

Ok, that one was a bit outdated. I just updated it, it could have contained a bug in the bed temperature (There was a bug caused by one of my updates)

I tested the bed heating today, and it works in the version you can build now.

[tpulti-bt 0]

At least no error anymore but we still measure a wrong temperature(357.3C). Is it possible that our board revision 1.5.3 is no longer supported?

[Daid 304]

1.5.3? I've never seen one of those, but I think it should work, the firmware should support the whole 1.5.x range. But the lowest I've tested is 1.5.4 but there can always be a bug somewhere in the code. I currently do not have the facilities to test themistor settings.

[calinb 11]

We know the Arduino works with the AD595 amplifier and a TC, as used in the UM hot end. Is there any reason other than cost not to use an AD595 and K-type TC for heated bed control?