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    Help, whine and 4000v measured on 3pin fan when idle

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    • gnydickundefined
      gnydick @dc42
      last edited by

      @dc42 I was hoping to reserve the 4 wire for the print cooling fan, although 8 haven't been able to find a 5015 24v blower that is 4 wire.

      Is this fan not usable? It's seems to work great, speed control is very good.

      Is there something wrong with this or is there a better way to configure/connect this fan?

      dc42undefined 1 Reply Last reply Reply Quote 0
      • 3DPMicroundefined
        3DPMicro
        last edited by 3DPMicro

        4kv probably would have jumped a noticable spark to your meter lead and dc42 would have been awarded inventor of the first ever flux capacitor. Think jigawatts
        https://youtu.be/VcZe8_RZO8c

        Duet controlled Lathe, micro mill, 3d printer and 1992 Haas VF2 VMC

        1 Reply Last reply Reply Quote 1
        • gnydickundefined
          gnydick
          last edited by gnydick

          PXL_20220830_012340402~2.jpg
          PXL_20220830_012358361~2.jpg

          mendenmhundefined 1 Reply Last reply Reply Quote 0
          • gnydickundefined
            gnydick
            last edited by

            PXL_20220830_012358361~2.jpg

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

              @gnydick if it's working well, don't worry about it.

              It appears that something is confusing your multimeter. What does the H symbol on the multimeter mean?

              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

              gnydickundefined 1 Reply Last reply Reply Quote 0
              • mendenmhundefined
                mendenmh @gnydick
                last edited by mendenmh

                @gnydick yeek! There is something funny with your meter.

                I agree, it shows an mV label when on that range, but I have no idea what it is doing. Have you tried putting it on an appropriate manual range and seeing if it still does this?

                I do have one idea. Is the "H" at the top 'Hold" mode. I have seen meters sometimes in hold that hold the number, but not the range info. Could it have captured that number in the mV range, and then switched to a volts range while still holding the display?

                1 Reply Last reply Reply Quote 0
                • gnydickundefined
                  gnydick @dc42
                  last edited by

                  @dc42 yes, H is for hold. Why is it receiving current when it's off?

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

                    @gnydick if the fan is turned complete off, it should only be receiving a few microamps of leakage current.

                    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

                    gnydickundefined 2 Replies Last reply Reply Quote 0
                    • gnydickundefined
                      gnydick @dc42
                      last edited by

                      @dc42 i guess that's enough to make it whine?

                      1 Reply Last reply Reply Quote 0
                      • mendenmhundefined
                        mendenmh
                        last edited by

                        It would be interesting to put a small load (10k resistor, e.g.) across the fan, and re-measure that voltage. Maybe the board has a leaky FET.

                        Also, it is possible that the fan draws very little current at low voltage. That may be low enough that nothing is biased on until the voltage is much higher. In that case, you may just be charging some tiny input capacitance, and a small current might create a significant voltage. The load resistor would tell more about this.

                        1 Reply Last reply Reply Quote 1
                        • gnydickundefined
                          gnydick @dc42
                          last edited by

                          @dc42 just nudging here. Is there anything I can do to stop this? With 4 tools, it's a cacophony of whining 😞

                          They're on toolboards.

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

                            @gnydick when exactly do they whine? Is it when they are turned on at a PWM that is too low to make them turn?

                            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

                            gnydickundefined 1 Reply Last reply Reply Quote 0
                            • gnydickundefined
                              gnydick @dc42
                              last edited by

                              @dc42 when they aren't powered at all.

                              T3P3Tonyundefined dc42undefined 2 Replies Last reply Reply Quote 0
                              • T3P3Tonyundefined
                                T3P3Tony administrators @gnydick
                                last edited by

                                @gnydick do they whine with the tacho output not connected?

                                www.duet3d.com

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                                • dc42undefined
                                  dc42 administrators @gnydick
                                  last edited by

                                  @gnydick said in Help, whine and 4000v measured on 3pin fan when idle:

                                  @dc42 when they aren't powered at all.

                                  Try disconnecting the tacho wire as @T3P3Tony suggests. If that resolves the issue, then connecting a small signal diode in series with the tacho wire should fix it. Note, when using a 3-wire fan the tacho will only read correctly when the fan is run at full PWM.

                                  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

                                  gnydickundefined 1 Reply Last reply Reply Quote 0
                                  • gnydickundefined
                                    gnydick @dc42
                                    last edited by

                                    @dc42 Is that a given with 3 wire fans or a duet quirk?

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

                                      @gnydick it's a given with 3 wire fans that if you PWM them (which they are not designed for, same as with most 2-wire fans), and the PWM is applied by interrupting the negative supply (which is how all 3D printer boards that I know of do it) then the tacho will not read accurately. This doesn't matter if the fan is used only at zero and full speed, which is typical for a hot end heatsink fan.

                                      If you want variable speed and a tacho readout, use a 4-wire fan.

                                      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

                                      gnydickundefined 1 Reply Last reply Reply Quote 0
                                      • gnydickundefined
                                        gnydick @dc42
                                        last edited by

                                        @dc42, ok, just curious. These are always running at full speed, so it's all good for a 3 wire. They're the cold section fans.

                                        1 Reply Last reply Reply Quote 0
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