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3.3V power problem

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  • gravatite
    I ve just started assembling my softrock rxtx ensemble, and I m having an issue with the 3.3V power supply. I could probably use higher magnification on this
    Message 1 of 4 , Jun 21, 2014
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      I've just started assembling my softrock rxtx ensemble, and I'm having an issue with the 3.3V power supply.  I could probably use higher magnification on this piece, but the solder joints look ok to me, and I measured the values of all the capacitors before installing to be sure I had the right ones.  I'm getting 4.92V at the USB 5V test which is ok, but for the 3.3V test at R10, I'm getting 4.3V.  Any ideas on what I should check to narrow down the problem?


    • c.oawright
      It is shorted by a solder bridge or the device is bad. Yes it is a small device and I thought mine was not bridged either, but with a bigger magnifying glass I
      Message 2 of 4 , Jun 21, 2014
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        It is shorted by a solder bridge or the device is bad. Yes it is a small device and I thought mine was not bridged either, but with a bigger magnifying glass I saw where the problem was.

        Charles
        W4CEW
      • Alan
        Original Message ----- Subject: [softrock40] 3.3V power problem ... I seem to remember troubles with C54. If you find nothing else try removing it. In fact it
        Message 3 of 4 , Jun 21, 2014
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          Original Message -----
          Subject: [softrock40] 3.3V power problem


          > I've just started assembling my softrock rxtx ensemble, and I'm having an issue with the 3.3V power supply. I could probably use
          > higher magnification on this piece, but the solder joints look ok to me, and I measured the values of all the capacitors before
          > installing to be sure I had the right ones. I'm getting 4.92V at the USB 5V test which is ok, but for the 3.3V test at R10, I'm
          > getting 4.3V. Any ideas on what I should check to narrow down the problem?
          >
          >
          >

          I seem to remember troubles with C54.
          If you find nothing else try removing it. In fact it is an optional component, the regulator should work without it.

          73 Alan G4ZFQ
        • warrenallgyer
          Make sure that pin 2 (yep.... that is the one in the middle on the 3-pin side... the most difficult one to get to) is grounded. Check by probing the pin itself
          Message 4 of 4 , Jun 21, 2014
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            Make sure that pin 2 (yep.... that is the one in the middle on the 3-pin side... the most difficult one to get to) is grounded. Check by probing the pin itself at the body of the device, not the solder pad.

            If your hand is steady enough and your soldering iron tip small enough it would not hurt to reheat each of the five connections just to be sure.

            Warren Allgyer
            9V1TD
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