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Bed heating error  

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Bed heating error


On first starting up from cold, the bed gets to 30 deg C, and I get a  "Err: MINTEMP BED"   heating error and the Bed heating turns off. Have to turn off/On the start again and the Bed heats up ok and prints ok.

Firmware is 3.9.3-3556

Is this a hardware or firmware issue?


Posted : 29/03/2021 7:40 pm
RE: Bed heating error

Hi Philippa,

If the ambient temperature is above 15C, then
Mintemp Bed,  is typically a sensor failure, the most common causes are:
Degenerating wires between the bed and the rambo case, (Probably right behind the Y axis Xable Clamp) the continuous flexing of the cables, causes metal fatigue and the connections go intermittent.
Loose connector on the rambo  board
Loose terminal in the plug housing at the Rambo end. 
another possibility is that the wires for the thermistor have been working their way into the cable strain relief, and have stretched the wires to the thermistor under the bed...  at best this can pull the thermistor out from under the adhesive tapes under the  heatbed... this would normally cause a thermal runaway, which you are not reporting.... 
Worst case, it can break the wires to the thermistor  which may give the intermittent problems you report. 

the thermistor should measure about 126Kohms at normal room temperature 20C  and 100Kohms at 25C

Regards Joan


I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 29/03/2021 8:34 pm