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VH-140c amp just started making a crazy new sound!!! Ideas?

Discussion in 'Pro Audio Equipment' started by neuromonkey, Jan 10, 2005.

  1. neuromonkey

    neuromonkey Guest

    I had just gotten a friend's VH-140c head cleaned & fixed up a bit when the damned thing started making this very odd sound--

    Imagine a bee flying back and forth, diving past your head. It's doing this over and over at around once a second, or slightly slower. Bzzzwww... Bzwww..Bzzzzzwww..-- NOT regularly timed. Continuous, but erratic. Then it'll stop for a couple of minutes. Then start for another 10 minutes...

    The sound _almost_ entirely vanishes when there's nothing in the input jack, but I can still hear it in there with the gain & volume cranked up. It *does* appear to be in the amp, and not a cable or my bass or the AC power or fluorscent lights. It's such a weird thing that I'm going to post a .wav file of it for people to listen to.

    It seems to start about 2 minutes after the amp is turned on. The only thing I can think of is maybe it's some capacitor discharging into the signal path...? It's the same in both channels and in both speaker outputs. None of the controls or effects seem to impact whatever is causing it. It really does sound like RF interference, but I've powered down everything else, and the amp's position doesn't seem to matter.

    Anyone have any ideas of what I might try? Replace caps maybe? Could it be the transformer? ARGH! Listen to a short snippet of it, at...

    http://radhack.com/dump/killerbee.wav

    In this recording it's pretty regular, but it usually speeds up & slows down for no reason that I've been able to discern.

    Thanks all!
     

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