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Softrock Lite 9.0 Divider or Mixer problem

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  • Kirk
    I had my SR Lite 9.0 working a couple of months ago but managed to break it somehow trying to get my 2 Meter board working. I did some voltage and continuity
    Message 1 of 7 , Oct 24, 2009
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      I had my SR Lite 9.0 working a couple of months ago but managed to break it somehow trying to get my 2 Meter board working. I did some voltage and continuity checks on the 9 pin connector using a DVM and it has not worked since. I checked the voltages on pin 2 and 14 of the mixer and they are 5.3 Volts, not 2.5 volts as specified in the instructions. I retouched all the solder connections on the divider and mixer and replaced R9 and R10 at the R10 test point as the voltage was 5.3 volts here as well, which is more than the 5 volt bus voltage (measures 4.95). Voltages were still high. I rechecked the voltage on Pin 14 on the mixer and by accident I grounded the connection and it started working. PSK31 on 7.035 as expected. As long as pin 14 is grounded, the SR works. Grounding pin 2 instead has no effect. At this point, I am not sure whether I have a divider problem or a mixer problem but leaning towards replacing the mixer. Any recommendations on next steps?

      Thanks,

      Kirk
    • Paul Playford
      Do you have an oscilloscope? de Paul, W8AEF ZF2JI/ZF2TA FO8DX/FO8PLA 8Q7AA XZ0A VU7RG TX5C ... From: Kirk To:
      Message 2 of 7 , Oct 24, 2009
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        Do you have an oscilloscope?

        de Paul, W8AEF

        ZF2JI/ZF2TA FO8DX/FO8PLA 8Q7AA XZ0A VU7RG TX5C

        ----- Original Message -----
        From: "Kirk" <n4kwo@...>
        To: <softrock40@yahoogroups.com>
        Sent: Saturday, October 24, 2009 7:43 PM
        Subject: [softrock40] Softrock Lite 9.0 Divider or Mixer problem


        >I had my SR Lite 9.0 working a couple of months ago but managed to break it
        >somehow trying to get my 2 Meter board working. I did some voltage and
        >continuity checks on the 9 pin connector using a DVM and it has not worked
        >since. I checked the voltages on pin 2 and 14 of the mixer and they are
        >5.3 Volts, not 2.5 volts as specified in the instructions. I retouched all
        >the solder connections on the divider and mixer and replaced R9 and R10 at
        >the R10 test point as the voltage was 5.3 volts here as well, which is more
        >than the 5 volt bus voltage (measures 4.95). Voltages were still high. I
        >rechecked the voltage on Pin 14 on the mixer and by accident I grounded the
        >connection and it started working. PSK31 on 7.035 as expected. As long as
        >pin 14 is grounded, the SR works. Grounding pin 2 instead has no effect.
        >At this point, I am not sure whether I have a divider problem or a mixer
        >problem but leaning towards replacing the mixer. Any recommendations on
        >next steps?
        >
        > Thanks,
        >
        > Kirk
        >
      • g8voip
        Hi Kirk, If the voltages on pins 2 and 14 of the mixer are 5.3 volts, there perhaps are two problems, firstly 5.3 volts is rather high to start off with, as
        Message 3 of 7 , Oct 25, 2009
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          Hi Kirk,

          If the voltages on pins 2 and 14 of the mixer are 5.3 volts, there perhaps are two problems, firstly 5.3 volts is rather high to start off with, as the output voltage from the 5v regulator U1 usually tends to be a little bit below 5v.

          I would measure the output pin of U1 to confirm what voltage is present there. I guess it could just be your DVM.

          Having just read your message again, I see you have already done that, forget those comments! The higher voltage suggests some AC waveform might be present perhaps on those pins.

          I suspect in probing around on the 9 pin connector you probably shorted the output of the Si570 on J1 pin 4 to something. Hopefully you have not killed the Si570.

          As to the voltages on pins 2 and 14 not being around 2.5v, that shows the divider stage is not operating, and that is confirmed with the input at R9 / R10 being at 5.3v as well. Highly improbably the the resistors would fail.

          One thought is to carefully check that U6 ground pin 7, actually is making a good connection to 0v. If it was floating, all pins of the device could do strange things.

          If it's not that, the next option is to lift pins 3 and 11 of U6 one at a time and check the junction of R9 / R10. I suspect U6 is faulty or you have a short somewhere. Lift the pins by using solder wick to remove most of the solder, then use a sewing needles and heat the pin and carefully lift it up clear of the pad. You can then measure the voltage on the pin and pad.

          That should hopefully confirm if it is the device or a short somewhere else.

          Not a good idea to short either pin 2 or 14 of the mixer to ground as you might end up damaging the outputs of U6.

          If you have access to an oscilloscope, it makes finding that type of fault considerably easier.

          73, Bob G8VOI


          --- In softrock40@yahoogroups.com, "Kirk" <n4kwo@...> wrote:
          >
          > I had my SR Lite 9.0 working a couple of months ago but managed to break it somehow trying to get my 2 Meter board working. I did some voltage and continuity checks on the 9 pin connector using a DVM and it has not worked since. I checked the voltages on pin 2 and 14 of the mixer and they are 5.3 Volts, not 2.5 volts as specified in the instructions. I retouched all the solder connections on the divider and mixer and replaced R9 and R10 at the R10 test point as the voltage was 5.3 volts here as well, which is more than the 5 volt bus voltage (measures 4.95). Voltages were still high. I rechecked the voltage on Pin 14 on the mixer and by accident I grounded the connection and it started working. PSK31 on 7.035 as expected. As long as pin 14 is grounded, the SR works. Grounding pin 2 instead has no effect. At this point, I am not sure whether I have a divider problem or a mixer problem but leaning towards replacing the mixer. Any recommendations on next steps?
          >
          > Thanks,
          >
          > Kirk
          >
        • Kirk Maskalenko
          No scope readily available but will try out the ideas when I am back in town. I am definitely getting output on the SI570 at the right frequency but may be
          Message 4 of 7 , Oct 26, 2009
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            No scope readily available but will try out the ideas when I am back in town.

            I am definitely getting output on the SI570 at the right frequency but may be getting noise or oscillations.

            Any recommendations for a hobbyist grade scope up to the task?

            Thanks,

            Kirk


            From: g8voip <g8voi.reeves59@...>
            To: softrock40@yahoogroups.com
            Sent: Sun, October 25, 2009 5:44:53 AM
            Subject: [softrock40] Re: Softrock Lite 9.0 Divider or Mixer problem

             

            Hi Kirk,

            If the voltages on pins 2 and 14 of the mixer are 5.3 volts, there perhaps are two problems, firstly 5.3 volts is rather high to start off with, as the output voltage from the 5v regulator U1 usually tends to be a little bit below 5v.

            I would measure the output pin of U1 to confirm what voltage is present there. I guess it could just be your DVM.

            Having just read your message again, I see you have already done that, forget those comments! The higher voltage suggests some AC waveform might be present perhaps on those pins.

            I suspect in probing around on the 9 pin connector you probably shorted the output of the Si570 on J1 pin 4 to something. Hopefully you have not killed the Si570.

            As to the voltages on pins 2 and 14 not being around 2.5v, that shows the divider stage is not operating, and that is confirmed with the input at R9 / R10 being at 5.3v as well. Highly improbably the the resistors would fail.

            One thought is to carefully check that U6 ground pin 7, actually is making a good connection to 0v. If it was floating, all pins of the device could do strange things.

            If it's not that, the next option is to lift pins 3 and 11 of U6 one at a time and check the junction of R9 / R10. I suspect U6 is faulty or you have a short somewhere. Lift the pins by using solder wick to remove most of the solder, then use a sewing needles and heat the pin and carefully lift it up clear of the pad. You can then measure the voltage on the pin and pad.

            That should hopefully confirm if it is the device or a short somewhere else.

            Not a good idea to short either pin 2 or 14 of the mixer to ground as you might end up damaging the outputs of U6.

            If you have access to an oscilloscope, it makes finding that type of fault considerably easier.

            73, Bob G8VOI


            --- In softrock40@yahoogro ups.com, "Kirk" <n4kwo@...> wrote:
            >
            > I had my SR Lite 9.0 working a couple of months ago but managed to break it somehow trying to get my 2 Meter board working. I did some voltage and continuity checks on the 9 pin connector using a DVM and it has not worked since. I checked the voltages on pin 2 and 14 of the mixer and they are 5.3 Volts, not 2.5 volts as specified in the instructions. I retouched all the solder connections on the divider and mixer and replaced R9 and R10 at the R10 test point as the voltage was 5.3 volts here as well, which is more than the 5 volt bus voltage (measures 4.95). Voltages were still high. I rechecked the voltage on Pin 14 on the mixer and by accident I grounded the connection and it started working. PSK31 on 7.035 as expected. As long as pin 14 is grounded, the SR works. Grounding pin 2 instead has no effect. At this point, I am not sure whether I have a divider problem or a mixer problem but leaning towards replacing the mixer. Any recommendations on next steps?
            >
            > Thanks,
            >
            > Kirk
            >


          • Paul Playford
            A Tektronix 465 with Tektronix probes. You ll never have to think about upgrading . de Paul, W8AEF ZF2JI/ZF2TA FO8DX/FO8PLA 8Q7AA XZ0A VU7RG TX5C ...
            Message 5 of 7 , Oct 26, 2009
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              A Tektronix 465 with Tektronix probes.  You'll never have to think about 'upgrading'.
               
              de Paul, W8AEF
               
              ZF2JI/ZF2TA  FO8DX/FO8PLA  8Q7AA  XZ0A  VU7RG  TX5C
              ----- Original Message -----
              Sent: Monday, October 26, 2009 7:17 PM
              Subject: Re: [softrock40] Re: Softrock Lite 9.0 Divider or Mixer problem

              No scope readily available but will try out the ideas when I am back in town.

              I am definitely getting output on the SI570 at the right frequency but may be getting noise or oscillations.

              Any recommendations for a hobbyist grade scope up to the task?

            • g8voip
              Hi Kirk, I guess the only real advise I could make about oscilloscopes, is go for the best you can afford. You could probably pick up a decent professional
              Message 6 of 7 , Oct 27, 2009
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                Hi Kirk,

                I guess the only real advise I could make about oscilloscopes, is go for the best you can afford. You could probably pick up a decent 'professional' one for the same price or less than a new one aimed at the 'hobby' end of the market.

                Scopes like the Tektronix 465 / 475 are extremely good, used them a lot in my professional work, however they certainly cannot be described as 'hobbyist' and are not the easiest to master using at first. Many of the features like delayed timebase etc would probably only rarely be used hobby wise.

                I would have thought it would have been better to go for a more 'basic' scope. My thoughts would be, dual trace (a must), bandwidth, minimum 20MHz.

                73, Bob G8VOI

                --- In softrock40@yahoogroups.com, "Paul Playford" <paul@...> wrote:
                >
                > A Tektronix 465 with Tektronix probes. You'll never have to think about 'upgrading'.
                >
                > de Paul, W8AEF
                >
                > ZF2JI/ZF2TA FO8DX/FO8PLA 8Q7AA XZ0A VU7RG TX5C
                > ----- Original Message -----
                > From: Kirk Maskalenko
                > To: softrock40@yahoogroups.com
                > Sent: Monday, October 26, 2009 7:17 PM
                > Subject: Re: [softrock40] Re: Softrock Lite 9.0 Divider or Mixer problem
                >
                >
                >
                >
                >
                > No scope readily available but will try out the ideas when I am back in town.
                >
                > I am definitely getting output on the SI570 at the right frequency but may be getting noise or oscillations.
                >
                > Any recommendations for a hobbyist grade scope up to the task?
                >
              • Kirk Maskalenko
                Replaced the divider this weekend and the 9.0RX is back in business! Thanks for the ideas. As far as scopes go, I would love to have a Tektronix 465 scope but
                Message 7 of 7 , Nov 1, 2009
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                  Replaced the divider this weekend and the 9.0RX is back in business! Thanks for the ideas.

                  As far as scopes go, I would love to have a Tektronix 465 scope but I am not ready to plunk down the cash being asked for one in decent shape.  I will keep an eye out for a bargain.

                  Kirk


                  From: g8voip <g8voi.reeves59@...>
                  To: softrock40@yahoogroups.com
                  Sent: Tue, October 27, 2009 3:15:51 AM
                  Subject: [softrock40] Re: Softrock Lite 9.0 Divider or Mixer problem

                   


                  Hi Kirk,

                  I guess the only real advise I could make about oscilloscopes, is go for the best you can afford. You could probably pick up a decent 'professional' one for the same price or less than a new one aimed at the 'hobby' end of the market.

                  Scopes like the Tektronix 465 / 475 are extremely good, used them a lot in my professional work, however they certainly cannot be described as 'hobbyist' and are not the easiest to master using at first. Many of the features like delayed timebase etc would probably only rarely be used hobby wise.

                  I would have thought it would have been better to go for a more 'basic' scope. My thoughts would be, dual trace (a must), bandwidth, minimum 20MHz.

                  73, Bob G8VOI

                  --- In softrock40@yahoogro ups.com, "Paul Playford" <paul@...> wrote:
                  >
                  > A Tektronix 465 with Tektronix probes. You'll never have to think about 'upgrading'.
                  >
                  > de Paul, W8AEF
                  >
                  > ZF2JI/ZF2TA FO8DX/FO8PLA 8Q7AA XZ0A VU7RG TX5C
                  > ----- Original Message -----
                  > From: Kirk Maskalenko
                  > To: softrock40@yahoogro ups.com
                  > Sent: Monday, October 26, 2009 7:17 PM
                  > Subject: Re: [softrock40] Re: Softrock Lite 9.0 Divider or Mixer problem
                  >
                  >
                  >
                  >
                  >
                  > No scope readily available but will try out the ideas when I am back in town.
                  >
                  > I am definitely getting output on the SI570 at the right frequency but may be getting noise or oscillations.
                  >
                  > Any recommendations for a hobbyist grade scope up to the task?
                  >


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