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v6.3 TX Mixer tests

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  • Grant McDuling
    G day all, I tested the TX Mixer last night and found the 5V regulator getting hot. Could smell it too. This is what I did: connected a jumper lead between the
    Message 1 of 2 , Jul 1 4:31 PM
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      G'day all,

      I tested the TX Mixer last night and found the 5V regulator getting hot. Could smell it too. This is what I did: connected a jumper lead between the hole for R26 and ground, and connected a wire around the 3 pins on J1 that are encircled by the white outline on the PCB. I actually plugged in the PAF board and made the connections on the corresponding pins there. When I measured the voltage on pin 16 of U3, I got around 2V, not 5V. Disconnecting the bridge on the PAF resulted in a measurement of 5V and the 5V regulator not heating up. I also don't understand taking a voltage reading at the hole for R26 by placing the DMM probes at the hole and ground. These two are linked by the wire bridge anyway, so this seems odd to me. What am I doing wrong?

      Regards
      Grant VK4JAZ
    • dan edwards
      grant   my 5v reg runs a tad hot also, FWIW. i slipped an extra, slightly large nut on the other side of the board.   thought about dropping b+ to 6 or 7
      Message 2 of 2 , Jul 1 8:53 PM
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        grant
         
        my 5v reg runs a tad hot also, FWIW. i slipped an extra, slightly large nut on
        the other side of the board.
         
        thought about dropping b+ to 6 or 7 volts, but that wont do, since the
        tx amps will need the full 12 v.
         
        otoh, my tx mixer seems ok, so far.....
         
        gl, 73, w5xz dan


        --- On Wed, 7/1/09, Grant McDuling <mcduling@...> wrote:

        From: Grant McDuling <mcduling@...>
        Subject: [softrock40] v6.3 TX Mixer tests
        To: softrock40@yahoogroups.com
        Date: Wednesday, July 1, 2009, 11:31 PM

        G'day all,

        I tested the TX Mixer last night and found the 5V regulator getting hot. Could smell it too. This is what I did: connected a jumper lead between the hole for R26 and ground, and connected a wire around the 3 pins on J1 that are encircled by the white outline on the PCB. I actually plugged in the PAF board and made the connections on the corresponding pins there. When I measured the voltage on pin 16 of U3, I got around 2V, not 5V. Disconnecting the bridge on the PAF resulted in a measurement of 5V and the 5V regulator not heating up. I also don't understand taking a voltage reading at the hole for R26 by placing the DMM probes at the hole and ground. These two are linked by the wire bridge anyway, so this seems odd to me. What am I doing wrong?

        Regards
        Grant VK4JAZ

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