Desperate VOX ac30tbx question

Discussion in 'Amps and Cabs' started by pyramids, Jul 24, 2008.

  1. pyramids

    pyramids Member

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    I recently bought a used ac30 tbx (british made w.computer wired board), i believe from 2000. It was in great shape and looks beautiful...

    after using it a couple times the standby light began to turn off while
    it was on and then the amp would fail to make a sound again. Brought it to a
    tech out here, he replaced a number of tubes including the
    gz34, checked out the fuses and transformers, and found nothing. He figured it
    could be the standby switch, so he replaced it with one that was soldered on,
    and it failed to fix the problem. He is not a Vox man, but said it is probably a
    random intermittent part that he would be unable to locate with out complete
    knowledge of the model. The amp will work on occasion, but then after a while
    the standby light will turn off and it will fail to work again for a long
    period. It's driving me insane, and i can't seem to find anyone in my area (Boston) that has enough Vox knowledge and is willing to tackle this. If anyone has any suggestions - technical or otherwise - i would greatly appreciate it.
     
  2. pyramids

    pyramids Member

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  3. Mastervolume

    Mastervolume Member

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    wow. stay away from a tech that can't figure out a vox power supply.

    You have a problem with the power supply. I would check the first couple of caps off the the transformer C45 and C46 one of those could be bad. this would cause the standby light to die and also kill your output. I would be surprised that you are not blowing fuses though. There is a 500ma fuse in line with those coming off of your rectifier.

    Take it to someone who knows what they are doing.
     
  4. Mastervolume

    Mastervolume Member

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    Might be just a bad ground there though. This kills the output w/o blowing the fuse and would also make your standby light turn off....
     
  5. Beam Tetrode

    Beam Tetrode Member

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    I experienced a similar problem with a TBX. Turned out to be a loose contact in one of the tube sockets.
     
  6. pyramids

    pyramids Member

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    Thanks for the suggestions. Standby light turns off and as goes any sound with it of course...

    I'll bring these issues to a different tech. Wonder if the new AC30 handwired heritage would be less likely to have such issues...
     
  7. Mastervolume

    Mastervolume Member

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    There is no gravity the earth sucks.


    all that to say I think that anything can break at anytime and usually the worst time.
     

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