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Re: [softrock40] Re: Bad chip?

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  • Sid Boyce
    Things happen now, in the past and will in the future. We all go there - turn the speaker volume down to take a phone call and much later wonder if the SDR app
    Message 1 of 28 , Nov 2, 2012
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      Things happen now, in the past and will in the future.
      We all go there - turn the speaker volume down to take a phone call and much later wonder if the SDR app has lost sound - been there, done that.
      73 ... Sid.

      On 02/11/12 02:32, wfahle wrote:
       

      It's embarrassing to admit this but here goes:
      Problem: unit doesn't kerchunk when connecting to USB
      Solution: pick up the earphones off the desk.
      :/

      Mind you, the voltage was still bad on that one chip. So I do have work to do if I want a transmitter. Received a good signal again tonight.

      --- In softrock40@yahoogroups.com, Sid Boyce <sboyce@...> wrote:
      >
      > You can consider yourself lucky if a zap killed the device rather than
      > weakening it and causing intermittent problems may be some time way
      > after it has been working perfectly.
      >
      > ESD precautions are always advised.
      > 73 ... Sid.
      >
      > On 01/11/12 13:00, wfahle wrote:
      > >
      > > See the epitaph elsewhere in this thread. I was using a 50W velleman
      > > temperature controlled soldering station, with a 3mm tip, which seems
      > > to have worked in most cases except for the removal. If you look at
      > > the pictures I think you will agree it was a fine soldering job; I
      > > never spent more than a second or two with the iron to the board,
      > > except maybe when soldering ground leads for resistors and such. That
      > > copper can suck up the heat.
      > >
      > > I suspect a static hit, as I was taking few precautions and another
      > > chip bit the dust somewhere in there too (not to mention a temperature
      > > drop requiring the heater to be run).
      > >
      > > --- In softrock40@yahoogroups.com
      > > <mailto:softrock40%40yahoogroups.com>, Lawrence Galea
      > > <galea_lawrence@> wrote:
      > > >
      > > > ps.
      > > > by the way, some problems are caused by not having high enough heat
      > > and having to keep the soldering iron too long on the pcb or a
      > > soldering iron which is not big enough to heat a big soldering pad
      > > especially when a chip or other component is already soldered or when
      > > a chip has a tab which has to be soldered to the pcb. When soldering a
      > > tab to the pcb, a 100W soldering gun will make the job much quicker
      > > and easier with less chance of damage to the pcb and the component
      > > than a soldering iron with a very fine tip as the time needed with the
      > > gun will be just a second or two while it will take much longer with a
      > > small fine-tipped iron. This is apart form the soldering being much
      > > easier and neater
      > > > Hope this helps.
      > > > Regards
      > > > Lawrence
      > > >
      > > >
      > > >
      > > >
      > > >
      > > > ________________________________
      > > > Da: Lawrence Galea <galea_lawrence@>
      > > > A: "softrock40@yahoogroups.com
      > > <mailto:softrock40%40yahoogroups.com>" <softrock40@yahoogroups.com
      > > <mailto:softrock40%40yahoogroups.com>>
      > > > Inviato: Giovedì 1 Novembre 2012 8:34
      > > > Oggetto: Re: [softrock40] Re: Bad chip?
      > > >
      > > >
      > > > Â
      > > > Another trick is to tread a thin insulated wire or a wire which does
      > > not take solder easily under the pins on one side, solder the end of
      > > the wire to a suitable solder pad near one side of the chip, then heat
      > > the pins one by one starting from the one farthest away from where you
      > > soldered the wire to the solder pad and when the solder melts pull the
      > > wire under the pin. This will push up the pin from the pcb. Do all the
      > > pins on one side and them to the other side.
      > > > Regards
      > > > Lawrence
      > > >
      > > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Chip pins
      > > >
      > > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
      > > ----------------
      > > > Â Solder padÂ
      > > 0-------------------------------------------------------Wire
      > > >
      > > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
      > > |Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â |
      > > >
      > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
      > > Chip
      > > >
      > > >
      > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â ----------------
      > > >
      > > >
      > > > Hope this explains.
      > > >
      > > > 0 is solder pad where wire is soldered
      > > > First heat the pin from the right hand side on the diagram and when
      > > solder melts pull the wire under the pin to the top of the page in
      > > this diagram and move towards the left pin by pin.
      > > >
      > > > Then do the same to the other side.
      > > >
      > > > ________________________________
      > > > Da: warrenallgyer <allgyer@>
      > > > A: softrock40@yahoogroups.com <mailto:softrock40%40yahoogroups.com>
      > > > Inviato: Giovedì 1 Novembre 2012 0:16
      > > > Oggetto: [softrock40] Re: Bad chip?
      > > >
      > > >
      > > > Â
      > > > Bill
      > > >
      > > > I feel your pain.... been there, done that... more than once in fact.
      > > >
      > > > A trick that will not help you now but may in the future: When
      > > removing multi-pin SMT devices I first solder all the pins together,
      > > using as little solder as possible. Then, when you apply the iron it
      > > can loosen one complete side at the same time. Carefully bending the
      > > chip up with needle nose applied to the ends will free this side. Then
      > > do the same on the other side and the chip comes up with minimal
      > > damage. Solderwick will clean up the lands and you are ready to
      > > install a replacement.
      > > >
      > > > After many many lands lifted and chips destroyed (I am a
      > > slow-learner) this trick has saved the day many times.
      > > >
      > > > Good luck to you.
      > > >
      > > > Warren Allgyer - W8TOD
      > > >
      > > > --- In softrock40@yahoogroups.com
      > > <mailto:softrock40%40yahoogroups.com>, "wfahle" <billfahle@> wrote:
      > > > >
      > > > > Well NOW it's the chip for sure. In an attempt to remove the IC to
      > > check voltages and such, the green covering began to burn through
      > > exposing the copper traces beneath. So I got out the clippers and
      > > clipped it loose from the board, so that I could remove each lead
      > > individually. This worked, but it tore up some of the pads in the
      > > process. I intend to replace it with this chip because it is available
      > > locally (and I don't think going SMT again is going to make life any
      > > easier):
      > > >
      > >
      > >
      >
      >
      > --
      > Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
      > Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
      > Senior Staff Specialist, Cricket Coach
      > Microsoft Windows Free Zone - Linux used for all Computing Tasks
      >



      -- 
      Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
      Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
      Senior Staff Specialist, Cricket Coach
      Microsoft Windows Free Zone - Linux used for all Computing Tasks
      
    • John Rabson
      ... When I was running the e-mail system for a major organisation, I received an annoyed phone call from the Director one Monday morning, complaining that his
      Message 2 of 28 , Nov 2, 2012
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        On 2 Nov 2012, at 12:39CET, Sid Boyce wrote:

         

        Things happen now, in the past and will in the future.
        We all go there - turn the speaker volume down to take a phone call and much later wonder if the SDR app has lost sound - been there, done that.
        73 ... Sid.

        When I was running the e-mail system for a major organisation, I received an annoyed phone call from the Director one Monday morning, complaining that his e-mail system did not work.

        I sent my most diplomatic technician to find out what had happened. He reported back a few minutes later -  the client had forgotten to switch his monitor on (in those days monitors tended to have separate power feeds and were always switched off at the weekend).

        John F5VLF


      • wfahle
        Well I m a mere Ph.D. in computer science with 20 years in the industry, so yes, I ve done this sort of thing dozens of times! PEBKAC
        Message 3 of 28 , Nov 2, 2012
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          Well I'm a mere Ph.D. in computer science with 20 years in the industry, so yes, I've done this sort of thing dozens of times! PEBKAC

          --- In softrock40@yahoogroups.com, John Rabson <john.rabson@...> wrote:
          >
          > On 2 Nov 2012, at 12:39CET, Sid Boyce wrote:
          >
          > >
          > > Things happen now, in the past and will in the future.
          > > We all go there - turn the speaker volume down to take a phone call and much later wonder if the SDR app has lost sound - been there, done that.
          > > 73 ... Sid.
          >
          > When I was running the e-mail system for a major organisation, I received an annoyed phone call from the Director one Monday morning, complaining that his e-mail system did not work.
          >
          > I sent my most diplomatic technician to find out what had happened. He reported back a few minutes later - the client had forgotten to switch his monitor on (in those days monitors tended to have separate power feeds and were always switched off at the weekend).
          >
          > John F5VLF
          > >
          >
        • Anthony Casorso
          PHd? Well, that explains it! ;) TonyBS EE (But master of BS)To: softrock40@yahoogroups.com From: billfahle@gmail.com Date: Fri, 2 Nov 2012 13:23:45 +0000
          Message 4 of 28 , Nov 2, 2012
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             PHd?  Well, that explains it!   ;)
             
            Tony
            BS EE (But master of BS)

            To: softrock40@yahoogroups.com
            From: billfahle@...
            Date: Fri, 2 Nov 2012 13:23:45 +0000
            Subject: [softrock40] Re: Bad chip?

             
            Well I'm a mere Ph.D. in computer science with 20 years in the industry, so yes, I've done this sort of thing dozens of times! PEBKAC

            --- In softrock40@yahoogroups.com, John Rabson <john.rabson@...> wrote:
            >
            > On 2 Nov 2012, at 12:39CET, Sid Boyce wrote:
            >
            > >
            > > Things happen now, in the past and will in the future.
            > > We all go there - turn the speaker volume down to take a phone call and much later wonder if the SDR app has lost sound - been there, done that.
            > > 73 ... Sid.
            >
            > When I was running the e-mail system for a major organisation, I received an annoyed phone call from the Director one Monday morning, complaining that his e-mail system did not work.
            >
            > I sent my most diplomatic technician to find out what had happened. He reported back a few minutes later - the client had forgotten to switch his monitor on (in those days monitors tended to have separate power feeds and were always switched off at the weekend).
            >
            > John F5VLF
            > >
            >


          • John Greusel
            I just had one recently- I was certain I had blown the BS170s with an inadvertent key down for 10 minutes and replaced them. Turned out it was a short in the
            Message 5 of 28 , Nov 2, 2012
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              I just had one recently- I was certain I had blown the BS170s with an inadvertent key down for 10 minutes and replaced them.
              Turned out it was a short in the microphone. The noise was horrendous.

              John
              KC9OJV

               



              From: Sid Boyce <sboyce@...>
              To: softrock40@yahoogroups.com
              Sent: Friday, November 2, 2012 6:39 AM
              Subject: Re: [softrock40] Re: Bad chip?

               
              Things happen now, in the past and will in the future.
              We all go there - turn the speaker volume down to take a phone call and much later wonder if the SDR app has lost sound - been there, done that.
              73 ... Sid.

              On 02/11/12 02:32, wfahle wrote:
               
              It's embarrassing to admit this but here goes:
              Problem: unit doesn't kerchunk when connecting to USB
              Solution: pick up the earphones off the desk.
              :/

              Mind you, the voltage was still bad on that one chip. So I do have work to do if I want a transmitter. Received a good signal again tonight.

              --- In softrock40@yahoogroups.com, Sid Boyce <sboyce@...> wrote:
              >
              > You can consider yourself lucky if a zap killed the device rather than
              > weakening it and causing intermittent problems may be some time way
              > after it has been working perfectly.
              >
              > ESD precautions are always advised.
              > 73 ... Sid.
              >
              > On 01/11/12 13:00, wfahle wrote:
              > >
              > > See the epitaph elsewhere in this thread. I was using a 50W velleman
              > > temperature controlled soldering station, with a 3mm tip, which seems
              > > to have worked in most cases except for the removal. If you look at
              > > the pictures I think you will agree it was a fine soldering job; I
              > > never spent more than a second or two with the iron to the board,
              > > except maybe when soldering ground leads for resistors and such. That
              > > copper can suck up the heat.
              > >
              > > I suspect a static hit, as I was taking few precautions and another
              > > chip bit the dust somewhere in there too (not to mention a temperature
              > > drop requiring the heater to be run).
              > >
              > > --- In softrock40@yahoogroups.com
              > > <mailto:softrock40%40yahoogroups.com>, Lawrence Galea
              > > <galea_lawrence@> wrote:
              > > >
              > > > ps.
              > > > by the way, some problems are caused by not having high enough heat
              > > and having to keep the soldering iron too long on the pcb or a
              > > soldering iron which is not big enough to heat a big soldering pad
              > > especially when a chip or other component is already soldered or when
              > > a chip has a tab which has to be soldered to the pcb. When soldering a
              > > tab to the pcb, a 100W soldering gun will make the job much quicker
              > > and easier with less chance of damage to the pcb and the component
              > > than a soldering iron with a very fine tip as the time needed with the
              > > gun will be just a second or two while it will take much longer with a
              > > small fine-tipped iron. This is apart form the soldering being much
              > > easier and neater
              > > > Hope this helps.
              > > > Regards
              > > > Lawrence
              > > >
              > > >
              > > >
              > > >
              > > >
              > > > ________________________________
              > > > Da: Lawrence Galea <galea_lawrence@>
              > > > A: "softrock40@yahoogroups.com
              > > <mailto:softrock40%40yahoogroups.com>" <softrock40@yahoogroups.com
              > > <mailto:softrock40%40yahoogroups.com>>
              > > > Inviato: Giovedì 1 Novembre 2012 8:34
              > > > Oggetto: Re: [softrock40] Re: Bad chip?
              > > >
              > > >
              > > > Â
              > > > Another trick is to tread a thin insulated wire or a wire which does
              > > not take solder easily under the pins on one side, solder the end of
              > > the wire to a suitable solder pad near one side of the chip, then heat
              > > the pins one by one starting from the one farthest away from where you
              > > soldered the wire to the solder pad and when the solder melts pull the
              > > wire under the pin. This will push up the pin from the pcb. Do all the
              > > pins on one side and them to the other side.
              > > > Regards
              > > > Lawrence
              > > >
              > > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Chip pins
              > > >
              > > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
              > > ----------------
              > > > Â Solder padÂ
              > > 0-------------------------------------------------------Wire
              > > >
              > > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
              > > |Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â |
              > > >
              > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
              > > Chip
              > > >
              > > >
              > > Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â ----------------
              > > >
              > > >
              > > > Hope this explains.
              > > >
              > > > 0 is solder pad where wire is soldered
              > > > First heat the pin from the right hand side on the diagram and when
              > > solder melts pull the wire under the pin to the top of the page in
              > > this diagram and move towards the left pin by pin.
              > > >
              > > > Then do the same to the other side.
              > > >
              > > > ________________________________
              > > > Da: warrenallgyer <allgyer@>
              > > > A: softrock40@yahoogroups.com <mailto:softrock40%40yahoogroups.com>
              > > > Inviato: Giovedì 1 Novembre 2012 0:16
              > > > Oggetto: [softrock40] Re: Bad chip?
              > > >
              > > >
              > > > Â
              > > > Bill
              > > >
              > > > I feel your pain.... been there, done that... more than once in fact.
              > > >
              > > > A trick that will not help you now but may in the future: When
              > > removing multi-pin SMT devices I first solder all the pins together,
              > > using as little solder as possible. Then, when you apply the iron it
              > > can loosen one complete side at the same time. Carefully bending the
              > > chip up with needle nose applied to the ends will free this side. Then
              > > do the same on the other side and the chip comes up with minimal
              > > damage. Solderwick will clean up the lands and you are ready to
              > > install a replacement.
              > > >
              > > > After many many lands lifted and chips destroyed (I am a
              > > slow-learner) this trick has saved the day many times.
              > > >
              > > > Good luck to you.
              > > >
              > > > Warren Allgyer - W8TOD
              > > >
              > > > --- In softrock40@yahoogroups.com
              > > <mailto:softrock40%40yahoogroups.com>, "wfahle" <billfahle@> wrote:
              > > > >
              > > > > Well NOW it's the chip for sure. In an attempt to remove the IC to
              > > check voltages and such, the green covering began to burn through
              > > exposing the copper traces beneath. So I got out the clippers and
              > > clipped it loose from the board, so that I could remove each lead
              > > individually. This worked, but it tore up some of the pads in the
              > > process. I intend to replace it with this chip because it is available
              > > locally (and I don't think going SMT again is going to make life any
              > > easier):
              > > >
              > >
              > >
              >
              >
              > --
              > Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
              > Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
              > Senior Staff Specialist, Cricket Coach
              > Microsoft Windows Free Zone - Linux used for all Computing Tasks
              >



              -- 
              Sid Boyce ... Hamradio License G3VBV, Licensed Private Pilot
              Emeritus IBM/Amdahl Mainframes and Sun/Fujitsu Servers Tech Support
              Senior Staff Specialist, Cricket Coach
              Microsoft Windows Free Zone - Linux used for all Computing Tasks
              


            • wfahle
              Ok, I ve recovered from the brain fart, and am back on track now. This OP-Amp (dual) is in the transmitter, as U6. Do you think noise will cause a problem? I
              Message 6 of 28 , Nov 2, 2012
              • 0 Attachment
                Ok, I've recovered from the brain fart, and am back on track now. This OP-Amp (dual) is in the transmitter, as U6. Do you think noise will cause a problem? I think I will try it anyway this weekend, because I am installing it dead-bug style with individual wires to each lead, so it will be easily replaced. This will allow me to finish the transmitter and see what I get signal-report wise.

                --- In softrock40@yahoogroups.com, "MICHAEL TALLENT" <mwtallent@...> wrote:
                >
                > You really want a low noise op-amp for this application as it will determine
                > the noise floor of your receiver. The data sheet you linked looks like
                > nothing special, so you will not get the performance that these receivers
                > are capable of.
                >
                > Mike T W6MXV
                >
                > ----- Original Message -----
                > From: "wfahle" <billfahle@...>
                > To: <softrock40@yahoogroups.com>
                > Sent: Wednesday, October 31, 2012 12:31 PM
                > Subject: [softrock40] Re: Bad chip?
                >
                >
                > > Well NOW it's the chip for sure. In an attempt to remove the IC to check
                > > voltages and such, the green covering began to burn through exposing the
                > > copper traces beneath. So I got out the clippers and clipped it loose from
                > > the board, so that I could remove each lead individually. This worked, but
                > > it tore up some of the pads in the process. I intend to replace it with
                > > this chip because it is available locally (and I don't think going SMT
                > > again is going to make life any easier):
                > > http://www.nteinc.com/specs/700to799/pdf/nte778a.pdf
                > >
                > > --- In softrock40@yahoogroups.com, "wfahle" <billfahle@> wrote:
                > >>
                > >> Ok, I pulled R16, and it still reads 5v at pin 1. R16 measures out at 10k
                > >> as it should, but with it pulled there is very little voltage at pin 2.
                > >> The current, since I can now measure it, across R16 is .24mA. The votage
                > >> at pin 7 doesn't change either; it's still almost zero. The others
                > >> besides 2 are unchanged. Pin 2 goes almost to zero vs. the 2.5 it had
                > >> been reading. I guess R16 becomes part of a voltage divider under the
                > >> circumstances; I don't understand circuits this complex. So I will try to
                > >> unseat U6 and see if there is a solder bridge under it from 1 to 8 or
                > >> something (they are across from each other).
                >
              • MICHAEL TALLENT
                Noise probably will not matter for the transmitting side, the output level may not be as good as amps designed for low voltage operation, but try it and see.
                Message 7 of 28 , Nov 2, 2012
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                  Noise probably will not matter for the transmitting side, the output level
                  may not be as good as amps designed for low voltage operation, but try it
                  and see.

                  Mike T

                  ----- Original Message -----
                  From: "wfahle" <billfahle@...>
                  To: <softrock40@yahoogroups.com>
                  Sent: Friday, November 02, 2012 12:46 PM
                  Subject: [softrock40] Re: Bad chip?


                  > Ok, I've recovered from the brain fart, and am back on track now. This
                  > OP-Amp (dual) is in the transmitter, as U6. Do you think noise will cause
                  > a problem? I think I will try it anyway this weekend, because I am
                  > installing it dead-bug style with individual wires to each lead, so it
                  > will be easily replaced. This will allow me to finish the transmitter and
                  > see what I get signal-report wise.
                  >
                  > --- In softrock40@yahoogroups.com, "MICHAEL TALLENT" <mwtallent@...>
                  > wrote:
                  >>
                  >> You really want a low noise op-amp for this application as it will
                  >> determine
                  >> the noise floor of your receiver. The data sheet you linked looks like
                  >> nothing special, so you will not get the performance that these receivers
                  >> are capable of.
                  >>
                  >> Mike T W6MXV
                  >>
                  >> ----- Original Message -----
                  >> From: "wfahle" <billfahle@...>
                  >> To: <softrock40@yahoogroups.com>
                  >> Sent: Wednesday, October 31, 2012 12:31 PM
                  >> Subject: [softrock40] Re: Bad chip?
                  >>
                  >>
                  >> > Well NOW it's the chip for sure. In an attempt to remove the IC to
                  >> > check
                  >> > voltages and such, the green covering began to burn through exposing
                  >> > the
                  >> > copper traces beneath. So I got out the clippers and clipped it loose
                  >> > from
                  >> > the board, so that I could remove each lead individually. This worked,
                  >> > but
                  >> > it tore up some of the pads in the process. I intend to replace it with
                  >> > this chip because it is available locally (and I don't think going SMT
                  >> > again is going to make life any easier):
                  >> > http://www.nteinc.com/specs/700to799/pdf/nte778a.pdf
                  >> >
                  >> > --- In softrock40@yahoogroups.com, "wfahle" <billfahle@> wrote:
                  >> >>
                  >> >> Ok, I pulled R16, and it still reads 5v at pin 1. R16 measures out at
                  >> >> 10k
                  >> >> as it should, but with it pulled there is very little voltage at pin
                  >> >> 2.
                  >> >> The current, since I can now measure it, across R16 is .24mA. The
                  >> >> votage
                  >> >> at pin 7 doesn't change either; it's still almost zero. The others
                  >> >> besides 2 are unchanged. Pin 2 goes almost to zero vs. the 2.5 it had
                  >> >> been reading. I guess R16 becomes part of a voltage divider under the
                  >> >> circumstances; I don't understand circuits this complex. So I will try
                  >> >> to
                  >> >> unseat U6 and see if there is a solder bridge under it from 1 to 8 or
                  >> >> something (they are across from each other).
                  >>
                • wfahle
                  It indicates 5v on pin 1, Just like the other one in that respect. With power off, I m currently reading 20.9 Kohms between pin 1 and pin 8, which when
                  Message 8 of 28 , Nov 3, 2012
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                    It indicates 5v on pin 1, Just like the other one in that respect. With power off, I'm currently reading 20.9 Kohms between pin 1 and pin 8, which when reviewing the schematic doesn't seem right. In fact the other dual op-amp which seems wired similarly is an open circuit between those pins, giving me more confidence that this is the problem. I'm reading 11Kohms between 8 and 2 on U6, which is probably where the 20.9 is coming from adding R16 (which spans 1 and 2). Any ideas anyone? Clearly there is a short somewhere, and not a bad chip after all.

                    --- In softrock40@yahoogroups.com, "MICHAEL TALLENT" <mwtallent@...> wrote:
                    >
                    > Noise probably will not matter for the transmitting side, the output level
                    > may not be as good as amps designed for low voltage operation, but try it
                    > and see.
                    >
                    > Mike T
                    >
                    > ----- Original Message -----
                    > From: "wfahle" <billfahle@...>
                    > To: <softrock40@yahoogroups.com>
                    > Sent: Friday, November 02, 2012 12:46 PM
                    > Subject: [softrock40] Re: Bad chip?
                    >
                    >
                    > > Ok, I've recovered from the brain fart, and am back on track now. This
                    > > OP-Amp (dual) is in the transmitter, as U6. Do you think noise will cause
                    > > a problem? I think I will try it anyway this weekend, because I am
                    > > installing it dead-bug style with individual wires to each lead, so it
                    > > will be easily replaced. This will allow me to finish the transmitter and
                    > > see what I get signal-report wise.
                    > >
                    > > --- In softrock40@yahoogroups.com, "MICHAEL TALLENT" <mwtallent@>
                    > > wrote:
                    > >>
                    > >> You really want a low noise op-amp for this application as it will
                    > >> determine
                    > >> the noise floor of your receiver. The data sheet you linked looks like
                    > >> nothing special, so you will not get the performance that these receivers
                    > >> are capable of.
                    > >>
                    > >> Mike T W6MXV
                    > >>
                    > >> ----- Original Message -----
                    > >> From: "wfahle" <billfahle@>
                    > >> To: <softrock40@yahoogroups.com>
                    > >> Sent: Wednesday, October 31, 2012 12:31 PM
                    > >> Subject: [softrock40] Re: Bad chip?
                    > >>
                    > >>
                    > >> > Well NOW it's the chip for sure. In an attempt to remove the IC to
                    > >> > check
                    > >> > voltages and such, the green covering began to burn through exposing
                    > >> > the
                    > >> > copper traces beneath. So I got out the clippers and clipped it loose
                    > >> > from
                    > >> > the board, so that I could remove each lead individually. This worked,
                    > >> > but
                    > >> > it tore up some of the pads in the process. I intend to replace it with
                    > >> > this chip because it is available locally (and I don't think going SMT
                    > >> > again is going to make life any easier):
                    > >> > http://www.nteinc.com/specs/700to799/pdf/nte778a.pdf
                    > >> >
                    > >> > --- In softrock40@yahoogroups.com, "wfahle" <billfahle@> wrote:
                    > >> >>
                    > >> >> Ok, I pulled R16, and it still reads 5v at pin 1. R16 measures out at
                    > >> >> 10k
                    > >> >> as it should, but with it pulled there is very little voltage at pin
                    > >> >> 2.
                    > >> >> The current, since I can now measure it, across R16 is .24mA. The
                    > >> >> votage
                    > >> >> at pin 7 doesn't change either; it's still almost zero. The others
                    > >> >> besides 2 are unchanged. Pin 2 goes almost to zero vs. the 2.5 it had
                    > >> >> been reading. I guess R16 becomes part of a voltage divider under the
                    > >> >> circumstances; I don't understand circuits this complex. So I will try
                    > >> >> to
                    > >> >> unseat U6 and see if there is a solder bridge under it from 1 to 8 or
                    > >> >> something (they are across from each other).
                    > >>
                    >
                  • Alan
                    ... Subject: [softrock40] Re: Bad chip? Not that one, in any case. ... I do not remember you giving the voltages you see on this chip. 73 Alan G4ZFQ
                    Message 9 of 28 , Nov 3, 2012
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                      ----- Original Message -----
                      Subject: [softrock40] Re: Bad chip? Not that one, in any case.


                      > It indicates 5v on pin 1, Just like the other one in that respect. With power off, I'm currently reading 20.9 Kohms between pin 1
                      > and pin 8, which when reviewing the schematic doesn't seem right. In fact the other dual op-amp which seems wired similarly is an
                      > open circuit between those pins, giving me more confidence that this is the problem. I'm reading 11Kohms between 8 and 2 on U6,
                      > which is probably where the 20.9 is coming from adding R16 (which spans 1 and 2). Any ideas anyone? Clearly there is a short
                      > somewhere, and not a bad chip after all.
                      >


                      I do not remember you giving the voltages you see on this chip.

                      73 Alan G4ZFQ
                    • wfahle
                      I am giving continuity checks now. I was reading 5v on pin 1, which was the original problem that made me suspect the chip was bad. In fact it looks like R15
                      Message 10 of 28 , Nov 3, 2012
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                        I am giving continuity checks now. I was reading 5v on pin 1, which was the original problem that made me suspect the chip was bad. In fact it looks like R15 is shorted to ground between it and C6+. That is not indicated in the schematic, so I'm now pulling R15.

                        --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
                        >
                        >
                        > ----- Original Message -----
                        > Subject: [softrock40] Re: Bad chip? Not that one, in any case.
                        >
                        >
                        > > It indicates 5v on pin 1, Just like the other one in that respect. With power off, I'm currently reading 20.9 Kohms between pin 1
                        > > and pin 8, which when reviewing the schematic doesn't seem right. In fact the other dual op-amp which seems wired similarly is an
                        > > open circuit between those pins, giving me more confidence that this is the problem. I'm reading 11Kohms between 8 and 2 on U6,
                        > > which is probably where the 20.9 is coming from adding R16 (which spans 1 and 2). Any ideas anyone? Clearly there is a short
                        > > somewhere, and not a bad chip after all.
                        > >
                        >
                        >
                        > I do not remember you giving the voltages you see on this chip.
                        >
                        > 73 Alan G4ZFQ
                        >
                      • wfahle
                        Found the problem. See other thread.
                        Message 11 of 28 , Nov 3, 2012
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                          Found the problem. See other thread.

                          --- In softrock40@yahoogroups.com, "wfahle" <billfahle@...> wrote:
                          >
                          > I am giving continuity checks now. I was reading 5v on pin 1, which was the original problem that made me suspect the chip was bad. In fact it looks like R15 is shorted to ground between it and C6+. That is not indicated in the schematic, so I'm now pulling R15.
                          >
                          > --- In softrock40@yahoogroups.com, "Alan" <alan4alan@> wrote:
                          > >
                          > >
                          > > ----- Original Message -----
                          > > Subject: [softrock40] Re: Bad chip? Not that one, in any case.
                          > >
                          > >
                          > > > It indicates 5v on pin 1, Just like the other one in that respect. With power off, I'm currently reading 20.9 Kohms between pin 1
                          > > > and pin 8, which when reviewing the schematic doesn't seem right. In fact the other dual op-amp which seems wired similarly is an
                          > > > open circuit between those pins, giving me more confidence that this is the problem. I'm reading 11Kohms between 8 and 2 on U6,
                          > > > which is probably where the 20.9 is coming from adding R16 (which spans 1 and 2). Any ideas anyone? Clearly there is a short
                          > > > somewhere, and not a bad chip after all.
                          > > >
                          > >
                          > >
                          > > I do not remember you giving the voltages you see on this chip.
                          > >
                          > > 73 Alan G4ZFQ
                          > >
                          >
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