#1
Recently bought my friends, vox ad30vt. Was working great until i started using the back powerknob.

Now sound doesn't come out of my amp unless i push it "in" more or push it "down"

Help or ideas anyone?
#2
Cold/broken solder joint? Have a friend who knows electronics a bit take the chassis out of the combo and have a look at it. Some resoldering might be all that's needed. If the knob is broken, there's a good chance it's just a bog standard part that you can purchase at any online electronics retailer.

Any amp tech, tv repairman, electrician, or electronics hobbyist will likely be able to sort this out for you (hint: pay friends in beer!).
#3
I had the same problem with my AD30VT.
Inside the pot, the fiber board that the traces were on, cracked.
It happened when the amp tipped over backwards.
Its a dual gang 100K linear pot. Kinda like this : http://www.mouser.com/ProductDetail/Alpha-Taiwan/RV122F-20-15F-B100K/?qs=sGAEpiMZZMtC25l1F4XBU%2fboegkbhXkIk6PEyEn4mMI%3d
That might be a direct replacement although I'm not sure about the shaft type.
But even if the shaft type is different, you could still use it, even with the same knob with an added trick or two.


You can get this : http://smallbear-electronics.mybigcommerce.com/alpha-dual-gang-16mm-solder-terminals-linear-audio/
And just use wires from the pot to the PCB.
Thats what I ended up doing although I got the pot from Radio Shack.
And the one I got was an audio taper (Taper doesn't really make a difference with this pot).

Its like a $3 part.

That pot is basically the wattage level control pot (IIRC, it really just controls the signal level going into the power amp stage).

But what Quailman said, might just be a bad solder joint.

Thats a great little amp.
IMO, worth fixing in this case as long as someone doesn't try to ream you on labor charges.
Last edited by CodeMonk at Nov 15, 2015,