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AS1100 , Yamaha amp , schematic please to identify component

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    AS1100 , Yamaha amp , schematic please to identify component

    Hi all

    Repairing the RIGHT channel output board .

    Replaced the 2 output devices & now working through circuitry .

    Discovered D130 ( S202 ) measuring O/C , but suspect there may be something special about it , as same diode on LEFT channel board is measuring 900 one way & 600 the other , on diode setting .
    Attached Files

    #2
    Re: AS1100 , Yamaha amp , schematic please to identify component

    It's a Current regulative diode , type S-202T , manufactured by Semitec .

    Yamaha part number ZE906900

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      #3
      Re: AS1100 , Yamaha amp , schematic please to identify component

      I would say it has gone open-circuit.
      S-202T is a current-regulator diode (basically a JFET) 100V 2mA rated.
      So I would expect a diode-drop in one polarity and low resistance sorta constant current in the other direction. It depends on your multimeter how much current it passes on diode-test.
      The datasheet doesn't shows forward direction it needs at least 1.7V-2.3V to begin regulating (pinch off). Internally the gate and source are tied together to make a 2-pin part.

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        #4
        Re: AS1100 , Yamaha amp , schematic please to identify component

        Thanks for the additional info

        Have ordered one just in case .

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          #5
          Re: AS1100 , Yamaha amp , schematic please to identify component

          Can confirm after receiving a new diode that previous reading mentioned is correct for this type of device .

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            #6
            Re: AS1100 , Yamaha amp , schematic please to identify component

            Rebuilt Right channel , but still not powering .

            Only yellow LED flashing , with no AC being released to mains transformer , due to protection relay not clicking over .

            Comment


              #7
              Re: AS1100 , Yamaha amp , schematic please to identify component

              Trying to isolate this down , but not easy .

              Pulled out power board & linked out relay contact , allowing supply to main transformer .

              I increased AC supply gradually using Variac .

              Right channel heat sink became fairly warm , & slightly hot .

              Disconnected Right channel audio board & tried again , to see if unit would power , but no .

              Suspect still an issue somewhere on Right channel ,& due to protection circuitry being very sensitive , won't allow me to power the amp with just left .

              Doesn't help that someone else has worked on this before me .

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