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RE: [LPFM] BZX7V5 Zener Diode [1 Attachment]

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  • Gareth Parker
    Ok, no damage should have occurred as a result of ZD1 failing. However if a power surge has cause this, there could be other faulty components. What happens
    Message 1 of 8 , 19 Mar

      Ok, no damage should have occurred as a result of ZD1 failing.  However if a power surge has cause this, there could be other faulty components.  What happens if you bypass the OLPD with a jumper?  Does the RF led light up?  Use a dummy load also when testing.

       

      ZD1 along with the current limiting resistor R47 (470R) supply 7.5v to the 4060 counter/divider IC which is used to generate the 6.25Khz pll reference, according to the datasheet it can handle upto 20v.  You may want to check R47 is not fried and still reads 470R (if it was a power surge).

       

      As a worst case if it still won’t work, for a small fee you can send it to me and I’ll get the scope on it.  I have every component for these boards in my inventory.

       

      Cheers,

       

      Gareth

       

      From: LPFM_Radio@yahoogroups.com.au [mailto:LPFM_Radio@yahoogroups.com.au]
      Sent: Monday, 20 March 2017 7:26 p.m.
      To: LPFM_Radio@yahoogroups.com.au
      Subject: Re: [LPFM] BZX7V5 Zener Diode [1 Attachment]

       

      Hi Gareth,

       

      Thanks - that would be much appreciated.  I have no idea what they’re worth but I’m more than happy to give you some dollars to cover the diodes plus your postage.

       

      It’s ZD1 (I’ve highlighted it in the attached PDF).  The diode is actually broken in half.  I have no idea how that happened!  Do you think this could have damaged other parts of the circuitry?

       

    • Edwin Hermann
      Hi all, A BZX7V5 Zener diode has blown on my NRG circuit board. I can’t seem to find any such part at Jaycar or online anywhere, but I can find plenty of
      Message 2 of 8 , 19 Mar
        Hi all,

        A BZX7V5 Zener diode has blown on my NRG circuit board.  I can’t seem to find any such part at Jaycar or online anywhere, but I can find plenty of datasheets on it!

        Can anyone with suitable electronics know-how recommend an alternative that will work?  (Preferably something available from Jaycar, but I’m don’t mind sourcing it elsewhere).

        I only dabble in electronics so although I can read the datasheet and find other diodes with a Zener voltage of 7.5 V, some but not all of the other parameters match and I don’t have enough knowledge to figure out whether these alternatives are suitable.

        Cheers,
        Edwin.

      • Gareth Parker
        I have a bag of hundreds, I ll send you a few, are you sure there s no other faulty parts? If the zener is not sinking voltage, its possible 13.8v may have got
        Message 3 of 8 , 19 Mar
          I have a bag of hundreds, I'll send you a few, are you sure there's no other faulty parts? If the zener is not sinking voltage, its possible 13.8v may have got into that part of the circuit and caused problems for the other components. Which zener was it?

          Gareth

          Sent from my iPhone

          On 20/03/2017, at 08:25, Edwin Hermann edwin@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:

           

          Hi all,


          A BZX7V5 Zener diode has blown on my NRG circuit board.  I can’t seem to find any such part at Jaycar or online anywhere, but I can find plenty of datasheets on it!

          Can anyone with suitable electronics know-how recommend an alternative that will work?  (Preferably something available from Jaycar, but I’m don’t mind sourcing it elsewhere).

          I only dabble in electronics so although I can read the datasheet and find other diodes with a Zener voltage of 7.5 V, some but not all of the other parameters match and I don’t have enough knowledge to figure out whether these alternatives are suitable.

          Cheers,
          Edwin.

        • Edwin Hermann
          Hi Gareth, Thanks - that would be much appreciated. I have no idea what they’re worth but I’m more than happy to give you some dollars to cover the diodes
          Message 4 of 8 , 19 Mar
          Hi Gareth,

          Thanks - that would be much appreciated.  I have no idea what they’re worth but I’m more than happy to give you some dollars to cover the diodes plus your postage.

          It’s ZD1 (I’ve highlighted it in the attached PDF).  The diode is actually broken in half.  I have no idea how that happened!  Do you think this could have damaged other parts of the circuitry?

        • Edwin Hermann
          Hi Gareth, I see. Yes, R47 stil reads around 470 ohms, so that’s good. If I bypass the OLPD with the jumper the RF LED does NOT light up. In fact
          Message 5 of 8 , 21 Mar
            Hi Gareth,

            I see.  Yes, R47 stil reads around 470 ohms, so that’s good.  If I bypass the OLPD with the jumper the RF LED does NOT light up.  In fact doesn’t light up in either situation and I had assumed that’s because of ZD1 (not sure if that’s a valid assumption!).

            This is my replacement transmitter board which hasn’t been in operation yet, but as my current transmitter is starting to fail (increasing amount of 100 Hz hum on the audio) I was going to swap in this board.

            I might take you up on your offer of replacement Zeners if that stills stands.  Since I can’t find them online (which is how this thread started!) I have no idea what they’re worth, and I’d like to give you a fair payment in return for the Zeners and your time/effort/postage, so please give me an idea of what they’re worth.

            I can email you separately with my details.

            Thanks,
            Edwin.


            On 19/03/2017, at 20:14, 'Gareth Parker' gareth41@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:


            Ok, no damage should have occurred as a result of ZD1 failing.  However if a power surge has cause this, there could be other faulty components.  What happens if you bypass the OLPD with a jumper?  Does the RF led light up?  Use a dummy load also when testing.

             

            ZD1 along with the current limiting resistor R47 (470R) supply 7.5v to the 4060 counter/divider IC which is used to generate the 6.25Khz pll reference, according to the datasheet it can handle upto 20v.  You may want to check R47 is not fried and still reads 470R (if it was a power surge).

             

            As a worst case if it still won’t work, for a small fee you can send it to me and I’ll get the scope on it.  I have every component for these boards in my inventory.

             

            Cheers,

             

            Gareth

             

            From: LPFM_Radio@yahoogroups.com.au [mailto:LPFM_Radio@yahoogroups.com.au] 
            Sent: Monday, 20 March 2017 7:26 p.m.
            To: LPFM_Radio@yahoogroups.com.au
            Subject: Re: [LPFM] BZX7V5 Zener Diode [1 Attachment]

             

            Hi Gareth,

             

            Thanks - that would be much appreciated.  I have no idea what they’re worth but I’m more than happy to give you some dollars to cover the diodes plus your postage.

             

            It’s ZD1 (I’ve highlighted it in the attached PDF).  The diode is actually broken in half.  I have no idea how that happened!  Do you think this could have damaged other parts of the circuitry?

             



          • Gareth Parker
            It s looks like something is not working in the RF section, does the 4427 get warm to the touch? The RF led should come on regardless of the PLL working or not
            Message 6 of 8 , 22 Mar
              It's looks like something is not working in the RF section, does the 4427 get warm to the touch? The RF led should come on regardless of the PLL working or not if the OLPD jumper is fitted.

              Your other board shouldn't be humming either, 

              Sent from my iPhone

              On 22/03/2017, at 08:58, Edwin Hermann edwin@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:

               

              Hi Gareth,


              I see.  Yes, R47 stil reads around 470 ohms, so that’s good.  If I bypass the OLPD with the jumper the RF LED does NOT light up.  In fact doesn’t light up in either situation and I had assumed that’s because of ZD1 (not sure if that’s a valid assumption!).

              This is my replacement transmitter board which hasn’t been in operation yet, but as my current transmitter is starting to fail (increasing amount of 100 Hz hum on the audio) I was going to swap in this board.

              I might take you up on your offer of replacement Zeners if that stills stands.  Since I can’t find them online (which is how this thread started!) I have no idea what they’re worth, and I’d like to give you a fair payment in return for the Zeners and your time/effort/postage, so please give me an idea of what they’re worth.

              I can email you separately with my details.

              Thanks,
              Edwin.


              On 19/03/2017, at 20:14, 'Gareth Parker' gareth41@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:


              Ok, no damage should have occurred as a result of ZD1 failing.  However if a power surge has cause this, there could be other faulty components.  What happens if you bypass the OLPD with a jumper?  Does the RF led light up?  Use a dummy load also when testing.

               

              ZD1 along with the current limiting resistor R47 (470R) supply 7.5v to the 4060 counter/divider IC which is used to generate the 6.25Khz pll reference, according to the datasheet it can handle upto 20v.  You may want to check R47 is not fried and still reads 470R (if it was a power surge).

               

              As a worst case if it still won’t work, for a small fee you can send it to me and I’ll get the scope on it.  I have every component for these boards in my inventory.

               

              Cheers,

               

              Gareth

               

              From: LPFM_Radio@yahoogroups.com.au [mailto:LPFM_Radio@yahoogroups.com.au] 
              Sent: Monday, 20 March 2017 7:26 p.m.
              To: LPFM_Radio@yahoogroups.com.au
              Subject: Re: [LPFM] BZX7V5 Zener Diode [1 Attachment]

               

              Hi Gareth,

               

              Thanks - that would be much appreciated.  I have no idea what they’re worth but I’m more than happy to give you some dollars to cover the diodes plus your postage.

               

              It’s ZD1 (I’ve highlighted it in the attached PDF).  The diode is actually broken in half.  I have no idea how that happened!  Do you think this could have damaged other parts of the circuitry?

               



            • Gareth Parker
              Sorry, hit the send by mistake before finished. The other board may not be bypassed properly at RF if its humming or it could be your modulation source. What
              Message 7 of 8 , 22 Mar
                Sorry, hit the send by mistake before finished.

                The other board may not be bypassed properly at RF if its humming or it could be your modulation source. What happens if you unplug the mod input? I'm assuming the pcb is mounted in a metal case?  Mount it on plastic mounts if not already, use 1nF ceramic caps from various points on the ground plane to the case, also do the same for the DC input pins before the ferrite beads. The antenna socket should be the only common ground from the pcb to the case. The audio input socket if it's mounted on the case should have its earth ring insulated from the case at its mounting point but bypassed at RF, use a 1nF and 10nF from earth ring to the case.  This is how I mount the NRG boards and they're absolutely silent. A bad power supply can also cause hum, try a different psu if possible.

                Gareth

                Sent from my iPhone

                On 22/03/2017, at 08:58, Edwin Hermann edwin@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:

                 

                Hi Gareth,


                I see.  Yes, R47 stil reads around 470 ohms, so that’s good.  If I bypass the OLPD with the jumper the RF LED does NOT light up.  In fact doesn’t light up in either situation and I had assumed that’s because of ZD1 (not sure if that’s a valid assumption!).

                This is my replacement transmitter board which hasn’t been in operation yet, but as my current transmitter is starting to fail (increasing amount of 100 Hz hum on the audio) I was going to swap in this board.

                I might take you up on your offer of replacement Zeners if that stills stands.  Since I can’t find them online (which is how this thread started!) I have no idea what they’re worth, and I’d like to give you a fair payment in return for the Zeners and your time/effort/postage, so please give me an idea of what they’re worth.

                I can email you separately with my details.

                Thanks,
                Edwin.


                On 19/03/2017, at 20:14, 'Gareth Parker' gareth41@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:


                Ok, no damage should have occurred as a result of ZD1 failing.  However if a power surge has cause this, there could be other faulty components.  What happens if you bypass the OLPD with a jumper?  Does the RF led light up?  Use a dummy load also when testing.

                 

                ZD1 along with the current limiting resistor R47 (470R) supply 7.5v to the 4060 counter/divider IC which is used to generate the 6.25Khz pll reference, according to the datasheet it can handle upto 20v.  You may want to check R47 is not fried and still reads 470R (if it was a power surge).

                 

                As a worst case if it still won’t work, for a small fee you can send it to me and I’ll get the scope on it.  I have every component for these boards in my inventory.

                 

                Cheers,

                 

                Gareth

                 

                From: LPFM_Radio@yahoogroups.com.au [mailto:LPFM_Radio@yahoogroups.com.au] 
                Sent: Monday, 20 March 2017 7:26 p.m.
                To: LPFM_Radio@yahoogroups.com.au
                Subject: Re: [LPFM] BZX7V5 Zener Diode [1 Attachment]

                 

                Hi Gareth,

                 

                Thanks - that would be much appreciated.  I have no idea what they’re worth but I’m more than happy to give you some dollars to cover the diodes plus your postage.

                 

                It’s ZD1 (I’ve highlighted it in the attached PDF).  The diode is actually broken in half.  I have no idea how that happened!  Do you think this could have damaged other parts of the circuitry?

                 



              • Edwin Hermann
                Hi Gareth, On the TX that’s humming, I’d tried removing the audio source and it still hums. I then used the same power supply on another transmitter which
                Message 8 of 8 , 14 Apr
                  Hi Gareth,

                  On the TX that’s humming, I’d tried removing the audio source and it still hums.  I then used the same power supply on another transmitter which is no longer suitable to run (it’s a 1-12 watts but for some reason puts only goes as low as 8 watts so it’s way over power) and there’s no hum.  So there must be something in my transmitter that has gone bad but I don’t know what.  Yes, the PCB is mounted in a metal case and it has capacitors between the case and the ground on the PCB.  It was fully built by NRG back in the old days.

                  It’s an old transmitter so I’m kind of ready to put it to one side if only I can get my backup TX board working.. :(

                  Regards,
                  Edwin.



                  On 23/03/2017, at 00:44, Gareth Parker gareth41@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:


                  Sorry, hit the send by mistake before finished.

                  The other board may not be bypassed properly at RF if its humming or it could be your modulation source. What happens if you unplug the mod input? I'm assuming the pcb is mounted in a metal case?  Mount it on plastic mounts if not already, use 1nF ceramic caps from various points on the ground plane to the case, also do the same for the DC input pins before the ferrite beads. The antenna socket should be the only common ground from the pcb to the case. The audio input socket if it's mounted on the case should have its earth ring insulated from the case at its mounting point but bypassed at RF, use a 1nF and 10nF from earth ring to the case.  This is how I mount the NRG boards and they're absolutely silent. A bad power supply can also cause hum, try a different psu if possible.

                  Gareth

                  Sent from my iPhone

                  On 22/03/2017, at 08:58, Edwin Hermann edwin@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:

                   

                  Hi Gareth,


                  I see.  Yes, R47 stil reads around 470 ohms, so that’s good.  If I bypass the OLPD with the jumper the RF LED does NOT light up.  In fact doesn’t light up in either situation and I had assumed that’s because of ZD1 (not sure if that’s a valid assumption!).

                  This is my replacement transmitter board which hasn’t been in operation yet, but as my current transmitter is starting to fail (increasing amount of 100 Hz hum on the audio) I was going to swap in this board.

                  I might take you up on your offer of replacement Zeners if that stills stands.  Since I can’t find them online (which is how this thread started!) I have no idea what they’re worth, and I’d like to give you a fair payment in return for the Zeners and your time/effort/postage, so please give me an idea of what they’re worth.

                  I can email you separately with my details.

                  Thanks,
                  Edwin.


                  On 19/03/2017, at 20:14, 'Gareth Parker' gareth41@... [LPFM_Radio] <LPFM_Radio@yahoogroups.com.au> wrote:


                  Ok, no damage should have occurred as a result of ZD1 failing.  However if a power surge has cause this, there could be other faulty components.  What happens if you bypass the OLPD with a jumper?  Does the RF led light up?  Use a dummy load also when testing.

                   

                  ZD1 along with the current limiting resistor R47 (470R) supply 7.5v to the 4060 counter/divider IC which is used to generate the 6.25Khz pll reference, according to the datasheet it can handle upto 20v.  You may want to check R47 is not fried and still reads 470R (if it was a power surge).

                   

                  As a worst case if it still won’t work, for a small fee you can send it to me and I’ll get the scope on it.  I have every component for these boards in my inventory.

                   

                  Cheers,

                   

                  Gareth

                   

                  From: LPFM_Radio@yahoogroups.com.au [mailto:LPFM_Radio@yahoogroups.com.au] 
                  Sent: Monday, 20 March 2017 7:26 p.m.
                  To: LPFM_Radio@yahoogroups.com.au
                  Subject: Re: [LPFM] BZX7V5 Zener Diode [1 Attachment]

                   

                  Hi Gareth,

                   

                  Thanks - that would be much appreciated.  I have no idea what they’re worth but I’m more than happy to give you some dollars to cover the diodes plus your postage.

                   

                  It’s ZD1 (I’ve highlighted it in the attached PDF).  The diode is actually broken in half.  I have no idea how that happened!  Do you think this could have damaged other parts of the circuitry?

                   






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