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Re: [softrock40] Re: I think I found my so-called bad chip problem.

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  • Alan
    ... Subject: [softrock40] Re: I think I found my so-called bad chip problem. ... Well done. You should have followed Robby s method, and told us the voltages
    Message 1 of 9 , Nov 3, 2012
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      ----- Original Message -----
      Subject: [softrock40] Re: I think I found my so-called bad chip problem.


      > And, reassembling, the voltages now check out (2.5 everywhere but pin 8 and 4, which are 5v and 0v,

      Well done.

      You should have followed Robby's method, and told us the voltages before you did anything more. Zero volts on pin 2 would have
      indicated where the fault was.
      Zero volts on pin 2 is the reason for 5V on pin 1.

      73 Alan G4ZFQ
    • John
      Use a toothbrush and Isopropyl alcohol and the pcb will look like it just left the factory. John G3UGY From: wfahle Sent: Saturday, November 03, 2012 9:50 PM
      Message 2 of 9 , Nov 4, 2012
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        Use a toothbrush and Isopropyl alcohol and the pcb will look like it just left the factory.
         
        John G3UGY
         

        From: wfahle
        Sent: Saturday, November 03, 2012 9:50 PM
        Subject: [softrock40] Re: I think I found my so-called bad chip problem.

         

        No offense taken; it's my first PCB. I did try rubbing alchohol but it made more of a mess. The whole board is a mess, but especially this part after all the diagnosis I went through to find the fault, including destroying a chip and soldering green wire onto it, etc. It will be a miracle if it works.

      • William Fahle
        Yes, I wish I had been more patient in trying things before starting to unsolder. In particular the solution came from continuity testing with the ohms turned
        Message 3 of 9 , Nov 5, 2012
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          Yes, I wish I had been more patient in trying things before starting
          to unsolder. In particular the solution came from continuity testing
          with the ohms turned up to 200k. This allowed me to see that certain
          circuits were not open, but were in fact 21k, which led to the
          diagnosis. In any case, I learned a lot doing this, so no regrets.

          So far it passes every test; I now discover I need a second soundcard
          to actually use the transmit. Also my primary soundcard is mono in, so
          it is useless as a receiver card, so while I get semi-readable signals
          from a backyard dipole, I'm not 100% sure what the receiver
          performance will be yet, as there are too many variables. A quickly
          thrown-up antenna, a bad soundcard, a new softrock build with problems
          along the way (and no scope to check the output), default calibration,
          all conspire to give me a big screen full of white noise with the
          occasional discernable cw signal, and muddy signals that I can only
          assume are ssb. I'm going to get a USB soundcard for the receiver side
          and use the built-in for transmit and then report back. The built-in
          definitely puts out stereo, so that shouldn't be an issue for
          transmit.
        • pond.james_pond
          You re not alone. Took me several days of frustrated reworking before finding the etch failure. I felt less charitable than yourself at the time.
          Message 4 of 9 , Nov 5, 2012
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            You're not alone. Took me several days of frustrated reworking before finding the etch failure. I felt less charitable than yourself at the time.

            --- In softrock40@yahoogroups.com, William Fahle <billfahle@...> wrote:
            >
            > Yes, I wish I had been more patient in trying things before starting
            > to unsolder. In particular the solution came from continuity testing
            > with the ohms turned up to 200k. This allowed me to see that certain
            > circuits were not open, but were in fact 21k, which led to the
            > diagnosis. In any case, I learned a lot doing this, so no regrets.
            >
            > So far it passes every test; I now discover I need a second soundcard
            > to actually use the transmit. Also my primary soundcard is mono in, so
            > it is useless as a receiver card, so while I get semi-readable signals
            > from a backyard dipole, I'm not 100% sure what the receiver
            > performance will be yet, as there are too many variables. A quickly
            > thrown-up antenna, a bad soundcard, a new softrock build with problems
            > along the way (and no scope to check the output), default calibration,
            > all conspire to give me a big screen full of white noise with the
            > occasional discernable cw signal, and muddy signals that I can only
            > assume are ssb. I'm going to get a USB soundcard for the receiver side
            > and use the built-in for transmit and then report back. The built-in
            > definitely puts out stereo, so that shouldn't be an issue for
            > transmit.
            >
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