Sherwood RD-8108R Audio Amplifier

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  • dick_barton
    Badcaps Legend
    • Aug 2015
    • 6642
    • Wales

    #1

    Sherwood RD-8108R Audio Amplifier

    I have the above unit that switches on and after a few seconds at most goes into standby mode. Whilst on (that is before going back into standby) the display is functioning.

    Has anyone the service manual for this model or perhaps could point me in the right direction.
    Thanks
    Willing to help but I'm no expert.
  • Andrew F. Ali
    Badcaps Legend
    • Jan 2014
    • 2450
    • Trinidad & Tobago

    #2
    Re: Sherwood RD-8108R Audio Amplifier

    Check PSU Trans, Diodes, etc......Then look at the Power Amp Output Semiconductors...any suspicious e-caps or scorched resistors??

    Comment

    • dick_barton
      Badcaps Legend
      • Aug 2015
      • 6642
      • Wales

      #3
      Re: Sherwood RD-8108R Audio Amplifier

      Thanks for your reply. Found a -15V three terminal 7915 regulator with -27V input and no output.
      Removed it and tested it on a power supply and it worked OK giving -15V output but I had no load connected.
      Put it back in and still had -27V input and 0V output.
      Added -15V from external power supply and the amplifier is up and running.
      Will replace the 7915 regulator
      Thanks
      Willing to help but I'm no expert.

      Comment

      • petehall347
        Badcaps Legend
        • Jan 2015
        • 4426
        • United Kingdom

        #4
        Re: Sherwood RD-8108R Audio Amplifier

        check the ground connection for the regulator

        Comment

        • dick_barton
          Badcaps Legend
          • Aug 2015
          • 6642
          • Wales

          #5
          Re: Sherwood RD-8108R Audio Amplifier

          Thanks for your reply.
          I now have the amplifier up and running but if anyone has the schematic for it I would very much appreciate it.
          Regards
          Willing to help but I'm no expert.

          Comment

          • petehall347
            Badcaps Legend
            • Jan 2015
            • 4426
            • United Kingdom

            #6
            Re: Sherwood RD-8108R Audio Amplifier

            http://www.givefile.net/smanuals/_av.../rd-8108r.html

            Comment

            • dick_barton
              Badcaps Legend
              • Aug 2015
              • 6642
              • Wales

              #7
              Re: Sherwood RD-8108R Audio Amplifier

              Thanks for the link but it seems to want to download unwanted files.
              Willing to help but I'm no expert.

              Comment

              • dick_barton
                Badcaps Legend
                • Aug 2015
                • 6642
                • Wales

                #8
                Re: Sherwood RD-8108R Audio Amplifier

                As I said earlier it is now up and running after changing the -15V regulator.
                Have run it over the last few days, however on two occasions it has emitted an extremely load pop from the speakers and gone into standby.
                Leaving it for a few minutes and then coming out of standby the amp will work again as though nothing un-towards had happened.
                Willing to help but I'm no expert.

                Comment

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