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SVT 7 pro no speaker output

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  • I did put a short on the base of Q33 (effectively leaving the CSD pin to do what it wants) and the amp came to life.
    I did power down after that just in case so did not have time to check the output of the 555.
    With the trigger pin high on the 555 the RS flip-flop inside should be in a 0 state thus shutting off the discharge pin (7).
    Will investigate more tommorrow .

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    • Shorting the base of Q33 does make the amp work!!
      The CSD pins are at 10v but now the 555 is doing strange things.
      The trigger pin (2) is fluctuating all over (Q31 and Q8 are not being energized) and U4, 29, 30 and 31
      are not active also.
      At one point the trigger pin (2) was at 3.6v and pins 7 and 6 were stable at 3.3v but pin 3 (output) was at 3.5v (might be a flaky 555 which I replaced).
      Checked Q31, Q8 and Q38 and all are OK.
      Some strange things happening here!!

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      • I have here a 0032543 rev: D and the U18-A pin 1 is not conected to pin 5 U18-B i have the schemayics of revB and is diferent of th circuit of Rev.
        Pin 6 and 7 are conected.
        I injected signal and in pin 1 is ok, but not in pin5 or pin 7
        Are signal in R96
        This circuit is diferent than the schematic

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        • Originally posted by Kadro View Post
          I have here a 0032543 rev: D and the U18-A pin 1 is not conected to pin 5 U18-B i have the schemayics of revB and is diferent of th circuit of Rev.
          Pin 6 and 7 are conected.
          I injected signal and in pin 1 is ok, but not in pin5 or pin 7
          Are signal in R96
          This circuit is diferent than the schematic
          May want to start a new thread, as this one is fairly old.

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          • This is the schematic that work
            Attached Files

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            • Cool.
              Do yourself a favour, start a new thread and repost it there.
              Nobody will follow a >100 post 5 year old thread which to boot does not refer to your amp.
              Juan Manuel Fahey

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