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Voltage sense

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  • James Ewen
    After many months of procrastination I finally have my OT2 powered up and connected to a radio. It does well on the transmit side, it s been beaconing away all
    Message 1 of 8 , Apr 21, 2007
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      After many months of procrastination I finally have my OT2 powered up
      and connected to a radio.

      It does well on the transmit side, it's been beaconing away all day,
      happily making packets. I haven't gotten it to listen to the incoming
      packets yet.

      My voltage seems to be reading much too low. I have JP2 on pins 1 and
      2, and am feeding in about 12.2 volts, but the unit is reporting 9.7
      volts.

      Looks like I have a bit more sleuthing about to do.

      James
      VE6SRV
    • James Ewen VE6SRV
      ... Having dug out a scope, I see that the VCC fed into the 2211 is sitting at about +0.2 volts. If I pull the 2211 out of the socket, I have +5 volts at pin
      Message 2 of 8 , Apr 23, 2007
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        --- In tracker2@yahoogroups.com, "James Ewen" <ve6srv@...> wrote:
        > I haven't gotten it to listen to the incoming
        > packets yet.

        Having dug out a 'scope, I see that the VCC fed into the 2211 is
        sitting at about +0.2 volts. If I pull the 2211 out of the socket, I
        have +5 volts at pin 1 of the socket. Looks like I have more digging
        still.

        James
        VE6SRV
      • zl1vfo
        ... Can you measure +5V on one end of R18 (51k) with the 2211 inserted & powered up? The other end of R18 goes to pin 7 of the 2211. Alternatively, with the
        Message 3 of 8 , Apr 24, 2007
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          --- In tracker2@yahoogroups.com, "James Ewen VE6SRV" <ve6srv@...> wrote:
          >
          > --- In tracker2@yahoogroups.com, "James Ewen" <ve6srv@> wrote:
          > > I haven't gotten it to listen to the incoming
          > > packets yet.
          >
          > Having dug out a 'scope, I see that the VCC fed into the 2211 is
          > sitting at about +0.2 volts. If I pull the 2211 out of the socket, I
          > have +5 volts at pin 1 of the socket. Looks like I have more digging
          > still.
          >
          > James
          > VE6SRV
          >

          Can you measure +5V on one end of R18 (51k) with the 2211 inserted &
          powered up? The other end of R18 goes to pin 7 of the 2211.

          Alternatively, with the power disconnected, you could always try a
          meter on low ohms range, and attempt to trace the PCB track back from
          pin 1 of the 2211 all the way back to the output pin of the 5 volt
          regulator (the one closest to the centre of the PCB).

          I suspect a high-resistance joint somewhere is causing the problem.

          Scott, any chance of a decent photo of the top and bottom of an
          unpopulated PCB, or even a simulated photo created by your CAD
          software ? I've got a semi-populated image located at
          <http://n1vg.net/proto_c.jpg> but I can't see where all the tracks go,
          also there's no bottom view... As I haven't got a PCB here in front
          of me, it makes it a bit hard to suggest test points to try & help
          James locate his problem.

          Cheers,
          Ian ZL1VFO
        • James Ewen
          ... Both sides of R18 see the same voltage. ... Yup, something like that, but it s pretty hard to follow the traces on the PCB under all the components. ...
          Message 4 of 8 , Apr 24, 2007
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            On 4/24/07, zl1vfo <zl1vfo@...> wrote:

            > Can you measure +5V on one end of R18 (51k) with the 2211 inserted &
            > powered up? The other end of R18 goes to pin 7 of the 2211.

            Both sides of R18 see the same voltage.

            > I suspect a high-resistance joint somewhere is causing the problem.

            Yup, something like that, but it's pretty hard to follow the traces on
            the PCB under all the components.

            > Scott, any chance of a decent photo of the top and bottom of an
            > unpopulated PCB, or even a simulated photo created by your CAD
            > software ? I've got a semi-populated image located at
            > <http://n1vg.net/proto_c.jpg> but I can't see where all the tracks go,
            > also there's no bottom view... As I haven't got a PCB here in front
            > of me, it makes it a bit hard to suggest test points to try & help
            > James locate his problem.

            I'm on a proto B board, but if you have them, layouts of all the
            boards top and bottom would be a big help for everyone attempting to
            troubleshoot. The schematic shows connections to different major
            components, but not the interconnection between them. For
            troubleshooting silly problems like this, you really need to know
            where the current is supposed to be flowing on the circuit board. It's
            a long process removing components to see where the traces go under
            them! :)

            James
            VE6SRV
          • 'Scott Miller'
            I ve posted top and bottom views of the Proto C board in the files section. Keep in mind that the bottom view is shown from the top side of the board, so it s
            Message 5 of 8 , Apr 24, 2007
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              I've posted top and bottom views of the Proto C board in the files section.  Keep in mind that the bottom view is shown from the top side of the board, so it's reversed relative to how you see it when you flip the board over.
               
              Scott


              From: tracker2@yahoogroups.com [mailto:tracker2@yahoogroups.com] On Behalf Of zl1vfo
              Sent: Tuesday, April 24, 2007 1:32 AM
              To: tracker2@yahoogroups.com
              Subject: [tracker2] Re: Voltage sense

              --- In tracker2@yahoogroup s.com, "James Ewen VE6SRV" <ve6srv@...> wrote:
              >
              > --- In tracker2@yahoogroup s.com, "James Ewen" <ve6srv@> wrote:
              > > I haven't gotten it to listen to the incoming
              > > packets yet.
              >
              > Having dug out a 'scope, I see that the VCC fed into the 2211 is
              > sitting at about +0.2 volts. If I pull the 2211 out of the socket, I
              > have +5 volts at pin 1 of the socket. Looks like I have more digging
              > still.
              >
              > James
              > VE6SRV
              >

              Can you measure +5V on one end of R18 (51k) with the 2211 inserted &
              powered up? The other end of R18 goes to pin 7 of the 2211.

              Alternatively, with the power disconnected, you could always try a
              meter on low ohms range, and attempt to trace the PCB track back from
              pin 1 of the 2211 all the way back to the output pin of the 5 volt
              regulator (the one closest to the centre of the PCB).

              I suspect a high-resistance joint somewhere is causing the problem.

              Scott, any chance of a decent photo of the top and bottom of an
              unpopulated PCB, or even a simulated photo created by your CAD
              software ? I've got a semi-populated image located at
              <http://n1vg. net/proto_ c.jpg> but I can't see where all the tracks go,
              also there's no bottom view... As I haven't got a PCB here in front
              of me, it makes it a bit hard to suggest test points to try & help
              James locate his problem.

              Cheers,
              Ian ZL1VFO

            • James Ewen
              ... Any chance you have the file for the Proto B board? There s enough difference that it is making it difficult to follow the power trace around the 2211.
              Message 6 of 8 , Apr 26, 2007
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                On 4/24/07, Scott Miller <scott@...> wrote:

                > I've posted top and bottom views of the Proto C board in the files section.

                Any chance you have the file for the Proto B board? There's enough
                difference that it is making it difficult to follow the power trace
                around the 2211.

                James
                VE6SRV
              • Ian ZL1VFO
                ... I was wondering about that myself, but I suspect what with the move n all, it s probably on a PC packed away somewhere :) On a side note, I might have a
                Message 7 of 8 , Apr 27, 2007
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                  > 2a. Re: Voltage sense
                  > Posted by: "James Ewen" ve6srv@... james_ewen
                  > Date: Thu Apr 26, 2007 12:33 pm ((PDT))

                  > On 4/24/07, Scott Miller <scott@...> wrote:

                  >> I've posted top and bottom views of the Proto C board in the files section.

                  > Any chance you have the file for the Proto B board? There's enough
                  > difference that it is making it difficult to follow the power trace
                  > around the 2211.

                  > James
                  > VE6SRV

                  I was wondering about that myself, but I suspect what with the move 'n
                  all, it's probably on a PC packed away somewhere :)

                  On a side note, I might have a go with Fireworks (graphics prog) & see
                  if I can merge the top and bottom views together so that pcb tracks
                  are easier to follow as they wind and wend their way around the PCB.

                  -Ian ZL1VFO
                • James Ewen
                  ... Yup, that s why I m not pestering a lot. As you can see from when this thread started, I m not in any huge hurry. I figure if I ve had the unit built up
                  Message 8 of 8 , Apr 27, 2007
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                    On 4/27/07, Ian ZL1VFO <zl1vfo@...> wrote:

                    > I was wondering about that myself, but I suspect what with the move 'n
                    > all, it's probably on a PC packed away somewhere :)

                    Yup, that's why I'm not pestering a lot. As you can see from when this
                    thread started, I'm not in any huge hurry. I figure if I've had the
                    unit built up for over 6 months before I put power to the unit, I can
                    wait for Scott to get unwound from his move.

                    > On a side note, I might have a go with Fireworks (graphics prog) & see
                    > if I can merge the top and bottom views together so that pcb tracks
                    > are easier to follow as they wind and wend their way around the PCB.

                    That can help quite a bit. I have flipped the bottom so that it looks
                    proper when looking at the board, but then you have to do the mental
                    gymnastics of flipping things back and forth as you move from one side
                    of the board to the other. It is pretty easy to create a third image
                    with semi transparency between the two sides.

                    James
                    VE6SRV
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