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Traynor YCV-40 No Reverb

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  • Originally posted by Helmholtz View Post
    All these signal levels at the caps make no sense.
    Was the amp even turned on?

    Your picture shows the meter in 200mV DC range. Not suitable.
    You need AC range for signals.

    I have a similar looking cheap DMM.
    It doesn't work for low level signals.
    Also it doesn't isolate DC from AC, which is essential for these measurements.

    For a meter test, directly measure the output of the signal generator.
    And measure a 9V battery in AC range.
    Measuring with two different dmm. Red one is autoranging but appears to be bad.

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    • When measuring a battery in AC setting, zero V is the correct reading as you only have DC and no AC.
      Forget the meter which reads 17V (for signal measuremnts).

      Now connect the autoranging meter to the signal generator output termials and see what you get.
      Last edited by Helmholtz; 10-11-2021, 05:28 PM.
      - Own Opinions Only -

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      • The Craftsman is a good meter. If the auto-range function is giving you problems, you can over ride it by using the range button. (see pg.10 of attached manual)
        Attached Files
        Originally posted by Enzo
        I have a sign in my shop that says, "Never think up reasons not to check something."


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        • BTW, never connect a meter in current (A, mA) mode (like in your middle picture) to a voltage source like a battery.
          It means a short to the battery and might even damage the meter.

          I have been using autoranging meters since at least 35 years. Hardly ever had a reason to switch to manual mode.
          Nice thing is they display the units with the value.
          - Own Opinions Only -

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          • Originally posted by Helmholtz View Post
            When measuring a battery in AC setting, zero V is the correct reading as you only have DC and no AC.
            Forget the meter which reads 17V (for signal measuremnts).

            Now connect the autoranging meter to the signal generator output termials and see what you get.
            Bought another dmm. Signal generator on 400hz/0.3v. + lead of dmm to + lead of signal generator, - lead of dmm to - lead of signal generator, dmm reading 0.100 ac volts.

            Comment


            • Originally posted by Helmholtz View Post
              When measuring a battery in AC setting, zero V is the correct reading as you only have DC and no AC.
              Forget the meter which reads 17V (for signal measuremnts).

              Now connect the autoranging meter to the signal generator output termials and see what you get.
              C9(+10.9acv, -10.9acv), C7(+.27acv, -.27acv),C3(+.27acv, -.27acv), C6(+.098acv, -.098acv).

              Comment


              • Originally posted by ca7922303 View Post

                C9(+10.9acv, -10.9acv), C7(+.27acv, -.27acv),C3(+.27acv, -.27acv), C6(+.098acv, -.098acv).
                Photo of dmm on C6

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                • That symbol means DC volts. Also the + or - means it must be DC. Signal must be measured with AC range.
                  That meter does not seem to have an AC volt range. Why aren't you using the Craftsman meter?
                  Originally posted by Enzo
                  I have a sign in my shop that says, "Never think up reasons not to check something."


                  Comment


                  • By the way, when you tested the Craftsman with a battery and the meter set to AC, we wanted to see a reading of zero. It passed the test. It should only read battery voltage when set to DC.
                    Originally posted by Enzo
                    I have a sign in my shop that says, "Never think up reasons not to check something."


                    Comment


                    • Originally posted by g1 View Post
                      That symbol means DC volts. Also the + or - means it must be DC. Signal must be measured with AC range.
                      That meter does not seem to have an AC volt range. Why aren't you using the Craftsman meter?
                      I put + or - to show what end of the cap I was measuring. Craftsman will not read DC volts or ohms correctly. Attached photos of new dmm manual.

                      Comment


                      • Originally posted by ca7922303 View Post

                        C9(+10.9acv, -10.9acv), C7(+.27acv, -.27acv),C3(+.27acv, -.27acv), C6(+.098acv, -.098acv).
                        Meter readings are not biased by the additional DC. Meter works fine.

                        These voltages look perfect and you have a strong rev. drive signal at U2 pin7.

                        Result is that the reverb drive/send circuit works fine: A 100mVrms signal at the PA IN produces an 11Vrms signal at the tank input.
                        Last edited by Helmholtz; 10-12-2021, 02:20 PM.
                        - Own Opinions Only -

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                        • Originally posted by g1 View Post
                          That symbol means DC volts. Also the + or - means it must be DC. Signal must be measured with AC range.
                          That meter does not seem to have an AC volt range. Why aren't you using the Craftsman meter?
                          The meter display shows AUTO/AC/V.
                          The reading is 0.098V, i.e. roughly 0.1V = 100mV.
                          Value makes sense as the generator probable shows peak-to-peak voltage of 0.3V, which corresponds to about 0.1Vrms.
                          I think the meter is good.
                          - Own Opinions Only -

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                          • We should be aware that all of the former info regarding signal yes/no is useless as none of the old meters is working properly for signal.
                            - Own Opinions Only -

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                            • And this after 147 posts?

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                              • Now we know that:

                                1) Reverb recovery stage works fine.
                                2) Reverb drive stage works fine.

                                Here's another test:
                                Connect the reverb output cable to tank and powered amp, reverb control up, speaker connected.
                                Connect the reverb input cable to the tank only.
                                Now momentarily (!) connect a 9V battery to the open plug contacts of the reverb input cable (may require the use of a battery clip).
                                Can you hear the reverberated pulse?
                                Last edited by Helmholtz; 10-12-2021, 11:28 PM.
                                - Own Opinions Only -

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