SOLVED Erratic temperature reading

Discussion in 'Calibration, Help, and Troubleshooting' started by Alex9779, Sep 14, 2016.

  1. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    Hey guys,
    for some days I have issue with my temp readings. First I thought this was because of the LIN_ADVANCE firmware and the reduce baud rate but it is also with the RC7 firmware I used before without issues.
    Heres a pic:
    Bildschirmfoto 2016-09-14 um 11.35.49.png
    The temperatures jump up and down by +-3° every now and then...
    Also the bed it seems but not by so much, just +-0.2°.
    I think this must be an issue with the RUMBA itself or the firmware or the amplifiers but I remember the bed was real stable before and now it is also not...
    The second hotend is not a real PT100 but just a resistor simulating ~21° so...

    After the current print is done I want to refresh the firmware and clear the EEPROM, then I will rerun the PID tuning and see if there is anything changing...

    Any other suggestions?
     
  2. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    Oh BTW, I realised that when I turn the button on the LCD to increase or decrease the federate the displayed values also fluctuate a lot until I stop to turn the button...
     
  3. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    Ok reflashing and resetting had no result...
    Then I unplugged all the stepper drivers and the temp were stable.
    I plugged them again one by one and when I plugged the Z stepper driver the temps did that jumping up and down again.
    So I changed the driver, nothing.
    I changed the firmware to use the E2 port for Z and a new driver, nothing.

    This sucks, as far as I can see the RUMBA has again an issue.
    Or why would a static resistor connected to the amplifier board jump up and down?
    Or why should both amplifiers be damaged the same way?
     
  4. PsyVision

    PsyVision Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    798
    Likes Received:
    248
    Hmmm, no idea at all to help you out :(
     
  5. Bluemalu

    Bluemalu Well-Known Member

    Joined:
    Mar 17, 2014
    Messages:
    95
    Likes Received:
    6
    Sounds like interference, the z axis motors are almost directly above the pt100 PCB. Just to confirm you could try and swap the drives over (to X and Y), or even disconnect the motor on the right.

    If it's EMI (electro magnetic interference), it could be a winding on the motor on its way out.

    Alternatively, having re read your previous the voltage regulator for the PT100 amps, LCD and possibly the Pi could be struggling. Do you have a volt meter available?
     
  6. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    I disconnected the motors too and the issue was still there...
    I used different and new stepper drivers... no change...
    I have a voltage meter but currently I have a print on the box I need until tomorrow. It works so far but the temp is not stable. I tuned the PID for the new socks and had a stable line. Today I had it like I didn't tune it, the line went up and down. I retuned them and no I have a low variation about +-2°... I think it is working because it is not really the temp but just the reading that has a problem.

    What shall I measure with the meter? My Pi has an external supply...
     
  7. Bluemalu

    Bluemalu Well-Known Member

    Joined:
    Mar 17, 2014
    Messages:
    95
    Likes Received:
    6
    Hmm, we're the temperatures stable before you put on your socks? If so then it could be something disturbed on the print head, when you get the opportunity you could try and remove the sensor from the block. This would also isolate any earth loops (strange unwanted effects with having split supplies and different references (in this case for 0V). It's generally good practice to make sure all of your 0 Volt lines are connected together. This is especially important for Earth leads (floating earths) but not relevant in this case.

    For the voltage you'll need to find the 0V line (in general any black wire but not always) then the +5V line going to the PT100 PCB's. 5V or greater is fine, if it's less (even 4.9V) can cause some circuits to act in unusual ways.
     
  8. Bluemalu

    Bluemalu Well-Known Member

    Joined:
    Mar 17, 2014
    Messages:
    95
    Likes Received:
    6
  9. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    This really sucks... I have no idea other than replacing the RUMBA...
    I exclude the amplifiers for the moment because all readings are influenced, look at this:
    Code:
    Send: M105
    Recv: ok T:25.7 /0.0 B:23.7 /0.0 T0:25.7 /0.0 T1:20.5 /0.0 @:0 B@:0 @0:0 @1:0
    Send: M105
    Recv: ok T:28.4 /0.0 B:24.1 /0.0 T0:28.4 /0.0 T1:23.7 /0.0 @:0 B@:0 @0:0 @1:0
    Send: M105
    Recv: ok T:24.8 /0.0 B:23.6 /0.0 T0:24.8 /0.0 T1:19.3 /0.0 @:0 B@:0 @0:0 @1:0
    Send: M105
    Recv: ok T:23.6 /0.0 B:23.3 /0.0 T0:23.6 /0.0 T1:17.9 /0.0 @:0 B@:0 @0:0 @1:0
    Four consecutive M105 of OctoPrint...
     
  10. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    Ok I think I may have found it... The connector from the amps seem to have not so good contact, wiggle it a bit and its ok... Seems I have to remove the PINs and work on them with a plier...
     
    Bluemalu and PsyVision like this.
  11. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    UPDATE: SOLVED!!! I can't believe it... But again it was the connector. Basically the one to the RUMBA but I pulled all PINs from all connectors of that cable one by one and bend the lip gripping the PINs... Now my temp I stable again!

    Code:
    Send: M105
    Recv: ok T:26.2 /0.0 B:24.2 /0.0 T0:26.2 /0.0 T1:20.8 /0.0 @:0 B@:0 @0:0 @1:0
    Send: M105
    Recv: ok T:26.3 /0.0 B:24.1 /0.0 T0:26.3 /0.0 T1:21.2 /0.0 @:0 B@:0 @0:0 @1:0
    Send: M105
    Recv: ok T:26.2 /0.0 B:24.2 /0.0 T0:26.2 /0.0 T1:21.1 /0.0 @:0 B@:0 @0:0 @1:0
    Send: M105
    Recv: ok T:26.1 /0.0 B:24.2 /0.0 T0:26.1 /0.0 T1:20.9 /0.0 @:0 B@:0 @0:0 @1:0
    Send: M105
    Recv: ok T:26.2 /0.0 B:24.2 /0.0 T0:26.2 /0.0 T1:21.2 /0.0 @:0 B@:0 @0:0 @1:0
     
  12. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    But I think I'll stay with the dual Z stepper drivers, switched them to DRVs too and now they are better sounding and more holding torque...
     
  13. Alex9779

    Alex9779 Moderator
    Staff Member

    Joined:
    Sep 4, 2015
    Messages:
    2,405
    Likes Received:
    731
    This looks much better...
    Bildschirmfoto 2016-09-15 um 16.12.32.png
     
    mike01hu and markoaurelije like this.
  14. Jean VISCONTE

    Jean VISCONTE Member

    Joined:
    May 15, 2016
    Messages:
    17
    Likes Received:
    6
    Hi Alex,

    I have the same problem time to time only on my dual's right extruder temp is 10 to 15° higher than ambiant, then fans never stop once extruder is off.

    I usually use a contact cleaning spray on the connector and everything is OK again. I do this once every two weeks or after printer not used for a while.

    Problem lies in low quality connectors, and I think, amplified by pollution from fumes out of nozzle, and some other products, like the spray I use to make my parts perfectly stick on the bed, this is some kind of glue.

    Regards
     

Share This Page