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Trouble with Dynacord powermate 1600 protection circuit

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  • Trouble with Dynacord powermate 1600 protection circuit

    I have one Dynacord power amplifier powermate 1600. The problem with this is it power up and suddently stops and fan is not working .I checked the secondary voltage the volts -15 and +15 are present .but i herd the relay is cutting off .if any body has any idea please help me. Thanks

    babu

  • #2
    If the relay is dropping out, then the amp is going into 'protect mode'.
    This is a powered mixer.
    There are a few voltages that have to be present other than the + & - 15 Vdc.
    For a starting point, I would suggest that you check the output transistors for a shorted condition.
    Here is the schematic.
    Attached Files

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    • #3
      Dear Jazz P Bass,
      thanks for your replay
      I checked the power transistor its ok .I disconnected the +-Vcc rail then also it is the same.one thing I noticed is that the relay drive -24 volt at the collector of transistor Q811 that is BC337 Is not coming .but there is -vss at the emiter.that circuit is accociated with number of transistor and ends with TL074.all other places the voltage is present.I am confused where to start?
      babu

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      • #4
        What is the base voltage of Q811?

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        • #5
          Dear Bass,
          the base voltage is -17v

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          • #6
            That circuit is giving me a headache!
            At -17 Vdc, Q811 is barely on.
            What is the collector voltage?
            On the left, Time In, is marked -11Vdc.
            Is that true?
            The fact that the amp does turn on but turns off gives you a chance to see where the input signal is coming from to turn it off.

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            • #7
              Dear bas it is true it is -10.5 when i measured.when the amplifier is on it should on the relay through the ptc resister .but it doesnot. I am also confused where to check

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              • #8
                Your reply is confusing.
                In the original post you said that the amp relay turns on & then off.
                Correct?
                How long does it stay on?
                At that point you should have 24 volts at the relay.
                What is the collector voltage of Q811?

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                • #9
                  Originally posted by babu123 View Post
                  when the amplifier is on it should on the relay through the ptc resister .
                  The relay 'bypasses' the PTC thermistor when the power supply is up & running.
                  A fault in the power amp section can turn the relay off.

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