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Thread: Concert Reverb Troubleshooting

  1. #1
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    May 2020
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    Concert Reverb Troubleshooting

    Hey folks, hoping to have found the right place, I’m thankful for any advice that helps me fix the issue that silences my amp.

    What I experience and know so far:
    If I turn the amp on, it maintains a constant hum, which seems to be the PT. However the pilot light stays off and the tubes won’t glow/heat up, while the speakers remain completely silent. I can switch channels (led light is indicating the active channel). Trying the various combinations of input, fx loop or return doesn’t change the situation. Turning all the knobs or use the 1/4 switch has no effects either. There’s seems to be no way to cause the speakers to react.
    Removing tubes doesn’t have an effect either. I checked both accessible fuses for continuity with success (Ohms read fine too)

    After some research I’m almost confident it’s the 6.3v circuit for heaters and the pilot light. Studying the service manual I assume that the 6.3v is the green cable from the PT, which seems to have a fuse that is I’m unable to find.

    Is it possible that the fuse is below the PT shield and it’s a thermal fuse that blow up after the PT got too hot?

    If so, is it safe to remove the PT shield and replace the fuse?

    Thanks for any advice!


  2. #2
    Forum Member phantomman's Avatar
    Join Date
    Aug 2007
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    Ten miles from the Mexican Frontier, in Arizona
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    Re: Concert Reverb Troubleshooting

    I concur with your assessment -- there's an issue with the 6.3 VAC supply. Either that tap is dead within the power tranny or that fuse is fried. You need to locate that fuse and investigate further.
    "When injustice becomes law then rebellion becomes duty."

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