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    blown wifi module worth repairing

    Duet Hardware and wiring
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    • ageis
      ageis last edited by

      Hi

      I have a duet wifi with it's wifi module blown. I am sure it has the magic smoke released because I could smell it. The rf can smells of burnt electronics.

      Is the usb connection powered by the wifi module or the cpu?

      If so is there another way I can determine if the cpu is dead?

      I do have access to equivalent of ft232rl module and a 20mhz bandwidth scope.

      I did try probing the crystal I did seem to get a waveform so am guessing it maybe still alive?

      If we deem it's worth repairing, I can replace the wifi module with Ethernet module right?

      Stephen6309 1 Reply Last reply Reply Quote 0
      • Stephen6309
        Stephen6309 @ageis last edited by Stephen6309

        @ageis
        :Is the usb connection powered by the wifi module or the cpu?<

        CPU

        1 Reply Last reply Reply Quote 0
        • ageis
          ageis last edited by

          OH thanks. I think it's cactus then because I don't get the usual device detected jazz when I plug it into my laptop without 12v power.

          Stephen6309 1 Reply Last reply Reply Quote 0
          • Stephen6309
            Stephen6309 @ageis last edited by Stephen6309

            @ageis Check U3.

            1 Reply Last reply Reply Quote 0
            • ageis
              ageis last edited by

              what exactly is u3? hmm I doubt I be able to solder that. It's smaller then a little finger! Time to ask a favour from my engineer friend

              Stephen6309 1 Reply Last reply Reply Quote 0
              • Stephen6309
                Stephen6309 @ageis last edited by

                @ageis I believe it supplies the 3.3v. There may be other damage not visible.

                1 Reply Last reply Reply Quote 0
                • ageis
                  ageis last edited by

                  is there a schematic for duet wifi 1.2? I can't find it on here
                  https://duet3d.dozuki.com/Wiki/Hardware_Overview#Section_PCB_revision_history

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

                    The link to the schematic is in https://duet3d.dozuki.com/Wiki/Hardware_Overview#Section_Open_Source.

                    Your first step is to check that the 3.3V rail is stable. If so, erase the firmware, reset, and see if the Bossa USB port appears on your PC.

                    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

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                    • ageis
                      ageis last edited by

                      I think the power supply fgor the 3.3v reg is cactus or at least critical bits of it like the two inductors they look dodgy. I dont trust it.

                      Can I suck off the 3.3v regulator then feed 3.3v from a psu then connect the usb cable?

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

                        @ageis said in blown wifi module worth repairing:

                        I think the power supply fgor the 3.3v reg is cactus or at least critical bits of it like the two inductors they look dodgy. I dont trust it.

                        Can I suck off the 3.3v regulator then feed 3.3v from a psu then connect the usb cable?

                        Yes you can try that. You can feed 3.3v in through an endstop connector or the Z probe connector.

                        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

                        1 Reply Last reply Reply Quote 0
                        • A Former User
                          A Former User last edited by

                          Might be worth checking if 5 or 3.3v rails are shorted to ground as a result of whatever failed before connecting external power, as that is a common failure mode

                          1 Reply Last reply Reply Quote 0
                          • ageis
                            ageis last edited by ageis

                            @bearer said in blown wifi module worth repairing:

                            h checking if 5 or 3.3v rails are shorted to ground as a result of whatever failed before connecting external power, as that is a common failure mo

                            ok can anyone think of likely scenarios I could of done this. I was waiting for the bed to heat up. all of a sudden puff I could smell magic smoke. I immediately switched the power off.

                            I just cheked, the 5v rail isn't shorted but the 3.3v rail is. I have already desoldered the esp8266 and the 3.3v ldo. So I reckon mr processor is "well done". Very low resistence few ohms. no bueno

                            I remeber watching a youtube video about finding shorts. He used a multimeter then probed around the board till he found the lowest resistence. Do you need an expensve mutlimeter to do that? I probed a few points they all appear to be 13.5 ohms

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

                              @ageis said in blown wifi module worth repairing:

                              @bearer said in blown wifi module worth repairing:

                              h checking if 5 or 3.3v rails are shorted to ground as a result of whatever failed before connecting external power, as that is a common failure mo

                              ok can anyone think of likely scenarios I could of done this. I was waiting for the bed to heat up. all of a sudden puff I could smell magic smoke. I immediately switched the power off.

                              As @Stephen6309, check whether U3 looks damaged. It's the small square chip near the VIN terminals. We've had a number of unexplained U3 failures recently, maybe there was bad batch of chips. If it's a genuine Duet, U3 failures normally qualify for replacement under warranty.

                              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

                              1 Reply Last reply Reply Quote 0
                              • ageis
                                ageis last edited by

                                it does look burned. Excellent warrenty cover. I doubt damage to the pads around the vin screw conector is covered.

                                Thanks for your help david. I will get myself so real kapton tape then attempt to repair it. At least it didn't set on fire. It does when you hold a lighter to it though.

                                I always been interested in smd. I am jelious of al the engineers who able to do it.

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

                                  @ageis said in blown wifi module worth repairing:

                                  it does look burned. Excellent warrenty cover. I doubt damage to the pads around the vin screw conector is covered.

                                  Thanks for your help david. I will get myself so real kapton tape then attempt to repair it. At least it didn't set on fire. It does when you hold a lighter to it though.

                                  I always been interested in smd. I am jelious of al the engineers who able to do it.

                                  If it's a genuine Duet, ask your supplier to replace it under warranty.

                                  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

                                  1 Reply Last reply Reply Quote 0
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