Unstable temperature readings on bed and hot end

[Albertomorazzi]

I'm having a weird problem with my A10 since i bought it 3 weeks ago : temperatures values on both bed and hot end are unstable, varying from 5 to 6 degrees every 5 seconds or so.

I never succeeded to get a proper print. Sometimes I have to wait for ages for the printing to start and the extrusion is always inconsistent, resulting in poor quality. I highly suspect the erratic temp reading to be the culprit, causing the hot end/extruder to respond inappropriately.

You can see on this graph that both readings are unstable, except for the bed when the hot end isn't warming up :



Tuning the PID didn't change a thing, which doesn't surprise me since the hot end temp is unstable even when cold. I tried with Marlin 1.1.7 and 1.1.9, same result.

This looks like noise in the arduino circuit. How can I find the cause of this problem ? Maybe I have a faulty motherboard ? I can't find any information on this, except for this guy https://www.geeetech.com/forum/viewtopi ... 98&t=61736 but he didn't get an answer...

[_kaktus_]

Hello.


In such a case I would look at how the actuating element that starts the heating is controlled.
I am thinking here of the MOSFET transistor.

What I mean by this is that the control may not be as it should be.
At least it would be worth checking.

You may need an oscilloscope or digital analyzer for this purpose.
Since I don't have this controller board, I can't reconstruct your situation and perform tests.

[William]

Heating and cooling?
Try to refer to this link and adjust the PID.
http://marlinfw.org/meta/gcode/
Use the M301,303,304 gcode

[Albertomorazzi]

Hello.


In such a case I would look at how the actuating element that starts the heating is controlled.
I am thinking here of the MOSFET transistor.

What I mean by this is that the control may not be as it should be.
At least it would be worth checking.

You may need an oscilloscope or digital analyzer for this purpose.
Since I don't have this controller board, I can't reconstruct your situation and perform tests.

Thanks but I hope it doesn't come to this, I don't have an oscilloscope and I would'nt know how to use it !

Heating and cooling?
Try to refer to this link and adjust the PID.
http://marlinfw.org/meta/gcode/
Use the M301,303,304 gcode

William read my post, the PID is tuned and the bed and hot end temperatures are unstable even at room temperature

[William]

Try to check these:
1.The thermistor of the heatbed and hotend(Normal is 80~120K NTC)
2.The voltage of the port for the thermistor(Normal is 5V)
3.Check the wires of the thermistor loose or not,if you have the clamps and you can hold it

[Albertomorazzi]

Thanks for the replies. I contacted Geeetech, they told me the board was defective and they are sending me another one.