Voc ac4 issues

Discussion in 'Amps and Cabs' started by earwax, Mar 27, 2015.

  1. earwax

    earwax Member

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    Recently having some issues with both my vox ac4's

    1. my ac4tv is having an issue that after about 10-15 minutes it gets this quiet ugly distortion sound no matter what the volume is or if it is in 1/4 watt mode or 4 watt mode. If I turn it off for 10 seconds and then back on the sound goes away for another 10-15 minutes more or less. I replaced the pre-amp tube so far but the shop didn't have an el84 and I am 14 hrs away from anyone who will repair amps. So I have ordered an el84 to give that a shot.

    2. the second ac4 I have is the recent handwired edition. This one has some sort of volume issue after a bit of playing it sort of fades to a thinner and quiter sound without distorting and then back in again. I have swapped the preamp tube on this one as well.

    I am hoping that this a tube issue but maybe that is wishful thinking for an easy solution. Any suggestions?
     
  2. Gretsch&Vox

    Gretsch&Vox Member

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    Volume fluctuations (#2) sound like a power tube issue. I would put a new EL84 in your AC4 hand wired.
     
  3. thousanium

    thousanium Member

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    I think I had something similar happen with my AC4TV, I would get a quiet distortion/crackle which would come and go. Turned out there was a wire arcing and if I looked down the grill I could see a tiny spark when it happened.
     
  4. earwax

    earwax Member

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    well I don't see any wires that could be arcing.

    I have switched around the preamp and power tubes and that doesn't seem to solve anything.

    I was always using the low gain input on the vox ac4hw1 and I switched to the high and the volume fluctuations have dissappeared on that input.

    It's hard to decide what to do with the ac4tv since I bought it only for $100. PCB's seem to make it hard to figure out what could be wrong.
     
  5. earwax

    earwax Member

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    Figured out the AC4Hw1. Seems so painfully obvious now. The low gain input jack is is failing. Glad its something simple.
     
  6. Gretsch&Vox

    Gretsch&Vox Member

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    I think I have the same issue with mine, though I use the high input. I would like to get it rectified. What is the fix?

    Thanks,
    Jay
     
  7. earwax

    earwax Member

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    Well I haven't fixed it yet. I was going to just solder in a new jack. I haven't looked to see if it's that complicated yet.
     
  8. Gretsch&Vox

    Gretsch&Vox Member

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    OK. Please keep us posted.
    Thanks. :)
     

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