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    Thermocouple randomly shows 2000°

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    • BoAundefined
      BoA @Marco_76
      last edited by

      @Marco_76 2000*C is a sign of open circuit I belive, so check wires and connectors.

      Marco_76undefined 1 Reply Last reply Reply Quote 0
      • Marco_76undefined
        Marco_76 @BoA
        last edited by

        @BoA Thanks for the feedback. Yes I know but there is no option of open circuit: the PT100 is a unique cable of 70 cm, and I soldered an extension of other 40 cm cables which are going directly to the Board 😞

        A Former User? BoAundefined 2 Replies Last reply Reply Quote 0
        • A Former User?
          A Former User @Marco_76
          last edited by

          @Marco_76 said in Thermocouple Daughter Board + PT100 randomly shows 2000°:

          Most of the times I just restart the 3D printer (even with no movement of the axes) and the message disappear

          -> try if it reappears by checking each axis alone: E.g. x-axis (only home x), if not, first disable (M18) all steppers again, then y-axis (only home y), if not...

          Especially check alone on the extruder if it is something there

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          • A Former User?
            A Former User @Marco_76
            last edited by

            @Marco_76 said in Thermocouple Daughter Board + PT100 randomly shows 2000°:

            @BoA Thanks for the feedback. Yes I know but there is no option of open circuit: the PT100 is a unique cable of 70 cm, and I soldered an extension of other 40 cm cables which are going directly to the Board

            Have you verified it by measuring the resistance in each wire?

            1 Reply Last reply Reply Quote 0
            • BoAundefined
              BoA @Marco_76
              last edited by

              @Marco_76 said in Thermocouple Daughter Board + PT100 randomly shows 2000°:

              there is no option of open circuit

              Belive, there is 😉 It is possible that the cable just started breaking internally, and this will get worse until there will be no connection at all. Been there 😉

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              • dc42undefined
                dc42 administrators
                last edited by dc42

                I presume you mean you have a PT100 daughter board, not a thermocouple daughter board.

                When you get the 2000C reading, send M305 P# if running RRF 2.x, or M308 S# if running RRF 3.x, where # is the heater (RRF2) or sensor (RRF3) number. In the response, what does it give as the "last error" ?

                Duet WiFi hardware designer and firmware engineer
                Please do not ask me for Duet support via PM or email, use the forum
                http://www.escher3d.com, https://miscsolutions.wordpress.com

                Marco_76undefined 1 Reply Last reply Reply Quote 0
                • Marco_76undefined
                  Marco_76 @dc42
                  last edited by

                  @dc42

                  Sorry I messed.
                  I have a Thermocouple Daughter Board + 2 K thermocouples

                  forget the PT100

                  dc42undefined 1 Reply Last reply Reply Quote 0
                  • dc42undefined
                    dc42 administrators @Marco_76
                    last edited by

                    @Marco_76 said in Thermocouple Daughter Board + PT100 randomly shows 2000°:

                    @dc42

                    Sorry I messed.
                    I have a Thermocouple Daughter Board + 2 K thermocouples

                    forget the PT100

                    OK, getting the last error report using M305 or M308 still applies.

                    Which version of the thermocouple daughter board do you have?

                    Duet WiFi hardware designer and firmware engineer
                    Please do not ask me for Duet support via PM or email, use the forum
                    http://www.escher3d.com, https://miscsolutions.wordpress.com

                    Marco_76undefined 1 Reply Last reply Reply Quote 0
                    • Marco_76undefined
                      Marco_76 @dc42
                      last edited by

                      @dc42

                      Here the error
                      Heater 0 uses Thermistor sensor channel 0, last error: sensor not ready, T:100000.0 B:4138.0 C:0.00e+0 R:4700.0 L:0 H:0

                      Sensors are E3D K-Type Thermocouples
                      The Board is the latest I think using MAC31856

                      Thanks

                      1 Reply Last reply Reply Quote 0
                      • dc42undefined
                        dc42 administrators
                        last edited by

                        Heater 0 evidently uses a thermistor. In the M305 or M308 command, please the heater number that corresponds to the thermocouple channel that gives the 2000C reading.

                        Duet WiFi hardware designer and firmware engineer
                        Please do not ask me for Duet support via PM or email, use the forum
                        http://www.escher3d.com, https://miscsolutions.wordpress.com

                        Marco_76undefined 1 Reply Last reply Reply Quote 0
                        • Marco_76undefined
                          Marco_76 @dc42
                          last edited by

                          @dc42

                          The physical sensor is definetly a E3D K-Type Thermocouple. Do you mean that I configured wrongly the sensor in config.g?

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                          • dc42undefined
                            dc42 administrators
                            last edited by

                            Please post your config.g file.

                            Duet WiFi hardware designer and firmware engineer
                            Please do not ask me for Duet support via PM or email, use the forum
                            http://www.escher3d.com, https://miscsolutions.wordpress.com

                            Marco_76undefined 1 Reply Last reply Reply Quote 0
                            • Marco_76undefined
                              Marco_76 @dc42
                              last edited by

                              @dc42

                              by reading config.g I realized that I run the check on P0 which is the bed and not the heater. Sorry again.
                              In fact in config.g I have the following.

                              ; Heaters
                              M305 P0 T100000 B4138 R4700 ; set thermistor + ADC parameters for heater 0 (bed)
                              M143 H0 S100 ; set temperature limit for heater 0 to 100C
                              M305 P1 X150 ; set thermistor for heater 1 thrugh the extended mini board
                              M143 H1 S280 ; set temperature limit for heater 1 to 280C
                              M305 P2 X151 ; set thermistor for heater 2 thrugh the extended mini board
                              M143 H2 S280 ; set temperature limit for heater 2 to 280C

                              by reading hetaer 1 with M308 P1 I get this message:
                              Heater 1 uses Thermocouple (MAX31856) sensor channel 150, last error: sensor short to other wiring, thermocouple type K, reject 50Hz

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                              • dc42undefined
                                dc42 administrators
                                last edited by dc42

                                It says there is a short to some other wiring. if you look at the thermocouple daughter board, you may find that the LED for that channel is lit. Here are some possible reasons:

                                1. You genuinely have an intermittent short circuit between one of the thermocouple wires and something else, most likely the hot end metalwork.

                                2. You have electrostatic discharge between something (most likely the hot end metalwork) and a thermocouple wire. This can happen quite easily because extruding plastic may build up static charge. The fix is to connect the hot end metalwork to Duet ground, either directly or via a high value resistor. Alternatively you can connect the hot end metalwork to the heater+ or fan+ wire using a high value resistor, e.g. 1Mohm.

                                3. The thermocouple wires are picking up a lot of interference from another cable, most likely a stepper motor cable. Avoid running the thermocouple wires n the same bundle as stepper motor wires. If you can't avoid it, use twisted pair wires for the stepper motor, and shield either the thermocouple wires or the stepper motor wires.

                                Duet WiFi hardware designer and firmware engineer
                                Please do not ask me for Duet support via PM or email, use the forum
                                http://www.escher3d.com, https://miscsolutions.wordpress.com

                                Marco_76undefined 2 Replies Last reply Reply Quote 0
                                • Marco_76undefined
                                  Marco_76 @dc42
                                  last edited by

                                  @dc42

                                  Thanks. I tend to exclude option 3 as I get the message immediately when I switch on the 3d printer, without any movement of steppers. Also, there is a flex3drive system, so the extruder is far from the sensor. I will investgate 1 & 2 and be back to you.

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                                  • Marco_76undefined
                                    Marco_76 @dc42
                                    last edited by

                                    @dc42 Thanks option 1 worked: I Moved the thermocouple a bit out of the e3d hotend (2mm) and now works well.

                                    I'm puzzled as the sensor (which is the e3d one) has a shilding which should avoid any contact with the hotend. Looks like the trial and error of Windows: restart and looks if it is fixed 🙂

                                    By the way thanks for your help, as always you are fast and to the point!

                                    Top!

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                                    • Marco_76undefined
                                      Marco_76
                                      last edited by

                                      Just an update for the benefit of the community. I got again the error and I fixed with solution 2. I temporarly put a cable attached to the ground, and when I switch on the 3d printer, if showing 2000 degrees, I just connect hotend to the ground and reset the heater. I will do a more stable solution as suggested by dc42.

                                      Thanks!

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