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AR ARS112PS Subwoofer - Hum

Discussion in 'Electronic Repair' started by RichK, Feb 18, 2006.

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  1. RichK

    RichK Guest


    This subwoofer is not that old and developed a hum, even with no signal
    going in.

    It was made in China - you guessed it. Do not have a schematic. Pulled the
    ckt assembly out. Workmanship is ugly, but do not see anything obvious.
    The ckt bd smells a bit , but it could be how these things smell :)

    There are 2 large caps 63V 6800uF in the PS. Would that be the culprit?


  2. Most likely.
  3. RichK

    RichK Guest

    Anyone know where to get these? Googled a lot, but do not see many

  4. DaveM

    DaveM Guest

    Coming in late on the thread, ... didn't see your original post. How loud
    is the hum? Can you hear any audio getting through?
    I repaired a powered subwoofer last year that exhibited a loud hum, but no
    audio was getting through. Turned out that one of the output transistors
    had shorted C-E and was causing extreme stress on the power supply.
    Replacing both output transistors fixed the problem.

    Dave M
    MasonDG44 at comcast dot net (Just substitute the appropriate characters in
    the address)

    Never take a laxative and a sleeping pill at the same time!!
  5. RichK

    RichK Guest

    Thanks for the hint Dave, it got me back to it. I was about to order caps
    (thanks for link Charles), but got back to more testing. The output
    transistors were OK, by VOM method. I started re-soldering some of the
    suspicious joints, as the whole thing did not show good workmanship. Also
    tightened the grounding screws. In that process I fixed the problem.

    For those wondering, AR (Acoustic Research) is just a name anymore. Not
    even sure who owns the name. Stuff is made in China, and not very well at

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