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Nad c325bee hifi amp

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  • Nad c325bee hifi amp

    I have this nad. At switch on it goes on for 2 secs then into protection
    Both channels are work at switch on and you can hear music before into protection node
    Puting a signal from the gen in I can see it on the primary side of the relay with the scope. Both look perfect.
    Right hand side has - 6.5v dc at relay

    I've looked over the right hand channel
    Metering all components. Can't find anything faulty /out of spec.
    All voltage rails are correct. With my limited skills on working out what is going on and the cause

    Any assistance would be grateful
    Service manual to follow

  • #2


    • #3
      My first suspects would be IC41, the DC offset integrator and the voltage amplifier module. The DCV on IC41 pin 3 should be about the same (a meter will load it slightly) as the output pre-relay i.e. -6.5V, pin 2 should be 0v and the output should be around -15V.

      Check R14 either end is 0V. If OK try swapping the voltage amp modules "AMP-SMD-MODULES" see if the problem follows the module. If the module is the issue I would not be surprised to find a leaky transistor but you can at least compare voltages on the transistors between the two to get some more clues.
      Experience is something you get, just after you really needed it.


      • #4
        Hi thanks nick. I checked out the smd pcb module. 82r resistor and 2sa1015 transistor. Tracks not brilliant. Fitted new parts and it's up and running.
        Running on test
        Many thanks