Harmon Kardon AVR340 no sound on 4 channels

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  • r2digital
    Member
    • Sep 2011
    • 39

    #1

    Harmon Kardon AVR340 no sound on 4 channels

    Hello, i had this amp sitting in the closet knowing that none of the channels were working. After taking it all apart i found 4 bulging main filter caps so i went ahead and replaced those with low ESR kmet caps. However after doing this it only restored sound to Surround L, Surround R, and Center channel. The main speaker fuse on the transformer F905/F906 keeps blowing so i decided to remove all of the transistor's on those 4 channels and measure them. All transistors appear to be in good working order(turned receiver on with none of them installed and fuse still blows). Checked dual emitter resistors on each channel and all seem ok. With that being said there's obviously a dead short some where in that section of the amp for the first 4 channels and im having some trouble trying to figure out how to locate it. This is where im asking for help from the gurus on this forum. Since this amp is so old i attached the avr340 service manual for quick access for whoever is willing to help me https://file.io/KkQoP1ZB3PpP
  • CapLeaker
    Leaking Member
    • Dec 2014
    • 7982
    • Canada

    #2
    disconnect CN19 on the board where these fuses are and check for a short on either side. There is a bridge rectifier that could be shorted on that power board, or something else is shorted on the main board. Your priority right now is to figure out on which board that short is.

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