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Traynor YCV-40 No Reverb

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  • Originally posted by ca7922303 View Post
    Those resistance measurements at the cable plugs look ok.
    I would have expected around 60 Ohm at the tank input and 215 Ohm at the tank output, but your values are in the ballpark.

    So up to now everything looks ok.

    Now carefully check and if necessary re-solder the reverb jack connections at the amp board.

    - Own Opinions Only -

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    • Originally posted by Helmholtz View Post

      Ok, now do the same with the tank output:
      Connect the other cable to the tank output jack (with both cables disconnected from amp) and measure resistance at the amp side RCA plug.
      And make sure I can read the unit in the display.
      Going back over return circuit since I have new dmm. Signal generator is set@400hz/.30V. Positive lead is connected to output RCA cable, amp is on: Signal(.099vac)
      r119(.099/.099 vac)
      r70(.099/.019 vac)
      c11(.019/.000 vac)
      c75(.019/.099 vac)
      U1 pin#7(.000 vac)
      C10(.000/.000 vac)
      R69(.000/.000 vac)
      r72(.000/.000 vac)
      R68(.000/OL)
      r71(.000/.000 vac)
      c63(.000/.008 vac)
      c12(.008/.000 vac)

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      • Originally posted by ca7922303 View Post

        Going back over return circuit since I have new dmm. Signal generator is set@400hz/.30V. Positive lead is connected to output RCA cable, amp is on: Signal(.099vac)
        r119(.099/.099 vac)
        r70(.099/.019 vac)
        c11(.019/.000 vac)
        c75(.019/.099 vac)
        U1 pin#7(.000 vac)
        C10(.000/.000 vac)
        R69(.000/.000 vac)
        r72(.000/.000 vac)
        R68(.000/OL)
        r71(.000/.000 vac)
        c63(.000/.008 vac)
        c12(.008/.000 vac)
        Getting 0.367 vac at signal generator, .099 at signal point on board above return jack.

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        • Originally posted by ca7922303 View Post

          Getting 0.367 vac at signal generator, .099 at signal point on board above return jack.
          All components in return circuit measure as specified with the exception of C63(225nf) schematic shows 47p, R68/69(59.2k), schematic shows 120k. Should I replace C63?

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          • Originally posted by g1 View Post

            The M581 board should have a version or revision number on it somewhere. Like maybe rev. or V. something? Or post some pics of the board if you can.
            There are several different schematic versions for the YCV40 and I'm not sure that we are using the correct one.
            Finally took board out again to replace C63. Photo attached shows board version.

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            • Originally posted by ca7922303 View Post

              All components in return circuit measure as specified with the exception of C63(225nf) schematic shows 47p, R68/69(59.2k), schematic shows 120k. Should I replace C63?
              How do measure caps? DMMs are not reliable at capacitance especially when measuring in-circuit., you'd need an LCR meter.

              Did you measure R68/69 out-of-circuit?
              - Own Opinions Only -

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              • Originally posted by Helmholtz View Post

                How do measure caps? DMMs are not reliable at capacitance especially when measuring in-circuit., you'd need an LCR meter.

                Did you measure R68/69 out-of-circuit?
                Replaced C63 and resoldered some pins in return circuit and now have reverb. Not complaining, glad to finally get it working but doesn't do much of anything until 5-7 then pretty good at 10. Really appreciate all the great help.

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                • Originally posted by ca7922303 View Post

                  All components in return circuit measure as specified with the exception of C63(225nf) schematic shows 47p,
                  Originally posted by ca7922303 View Post

                  Replaced C63 and resoldered some pins in return circuit and now have reverb.

                  C63 is the big green one in that photo you posted earlier. That is definitely not 47p and I don't think it is anything that Yorkville uses stock. So likely it is from a botched previous repair or a modification attempt. If it is a mod attempt, there may be other changes that are resulting in having to turn reverb up to 10 for it to sound good.
                  But even with that cap there, I don't think it would have killed the reverb, so more likely that your re-soldering was the fix.






                  Click image for larger version  Name:	fetch?photoid=942652.jpg Views:	0 Size:	2.58 MB ID:	943621



                  "Everything is better with a tube. I have a customer with an all-tube pacemaker. His heartbeat is steady, reassuring and dependable, not like a modern heartbeat. And if it goes wrong he can fix it himself. You can't do that with SMD." - Mick Bailey

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                  • C63 is in the NFB path of the rev. return opamp. A large cap value of 220nF there will greatly lower gain.
                    Last edited by Helmholtz; 10-19-2021, 01:54 AM.
                    - Own Opinions Only -

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