Question: Mystery Vox AC30 Mod, what is it?

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Creedasaurus, Feb 24, 2012.

  1. Creedasaurus

    Creedasaurus Member

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    Ok, so I bought this Vox AC30CCH a few years back. It has played wonderfully for most of that time (except certain problems with the effects loop at one point). Well I popped it open to pull the recently bad Power Tubes out and I noticed something out of the ordinary. I know people sometimes mod their amps. But I have no idea where to start with how to figure out what mod was done here. And who knows. Maybe it just needed a new resistor in that spot for some reason so its the same value. But I dont know.

    Could anyone figure out what was done according to these photos?

    Its just on the main board that you see when you pop the back off if that helps. Not the one with the pre-amp tubes mounted on it. Anyway, any info would be great.

    [​IMG][​IMG]
     
  2. mcdes

    mcdes Member of no importance

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    That sure is the lazy way! Lol
     
  3. Creedasaurus

    Creedasaurus Member

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    I wrote Vox an email about it. Hope Korg is a cool enough company to reply to stuff like this. :rolleyes:
     
  4. Prairie Dawg

    Prairie Dawg Member

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    It appears that the resistor has merely been scabbed onto the stub ends of the old one which may have failed. My AC30CC schematic shows R141 as being a 220 ohm resistor. That looks like a 22 ohm resistor red-red brown.

    You might want to check me on this.

    If so it is the wrong value and it was put in by someone too lazy to remove the circuit board. On the other hand if your amp is working OK I'd leave it alone.
     
  5. guitarcapo

    guitarcapo Senior Member

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    It certainly would dissipate heat better that way
     
  6. Creedasaurus

    Creedasaurus Member

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    Oh excellent! Thank's a bunch for that. And I just checked a color code chart and it is actually a 220 ohm like the original. So that's good. Now I just wonder what it effects. It seems to me like the trem on it is a little slower than others. So for some reason I thought maybe this was effecting it.

    But I have no idea. Relative noob to electronics here. I've only built a few BYOC pedals. :bounce
     
  7. VacuumVoodoo

    VacuumVoodoo Member

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    Red-red-brown is 220 ohm, 22 is red -red-black.
     
  8. michael stuart 57

    michael stuart 57 Member

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    love those pcbs

    original tech was probably avoiding damaging the traces on the board
     

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