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    Problem with the 5v to 3.3v regulator

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    • Shen
      Shen last edited by

      I'm having a problem with my duet wifi, it just started right after upgrading to 1.19beta, not sure if it's just an coincidence. When I turn on the board(even with nothing connected), the 3.3v green light turns off after a few seconds. After some investigation, I found the problem is with the TC2117-3.3VDBTR 5v to 3.3v regulator, it gets really hot in a few seconds and stops working. If I place a block of metal on top of the chip to cool it, it would work as long as metal is cool. Before I try to replace the chip I just want to know if the problem is caused by the chip itself, or some load(I have nothing connected, could there be a short somewhere) on the 3.3v that overloads the chip. Any idea?

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      • Shen
        Shen last edited by

        After some more investigation, I found the resistance between the +5 and ground is only 10 ohms. So I guess the TC2117-3.3VDBTR shorted internally that's why it gets so hot? I'm surprised it still works with cooling.

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        • dc42
          dc42 administrators last edited by

          That does sound like a very odd failure mode.

          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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          • Shen
            Shen last edited by

            Looks like the problem is indeed caused by the TC2117-3.3VDBTR chip. I removed it and the resistance on the chip between 5V and ground still measures 10 ohms. With a external 3.3v source connected to the duet wifi board, everything works fine without generating any excessive heat. Now I just hope I won't make too big of a mess soldering on a new one.

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            • dc42
              dc42 administrators last edited by

              If you've removed the old regulator without damaging the PCB traces, you've done the difficult bit.

              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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