hmmmm, maybe im reading the diagram wrong but isnt this still showing ... clipping R529 and Jumping EP104 to EP503,... which contact point has changed ?
I ended up finding a old 9" B&W RCA AER095. i havent had a chance to open it up yet, and i have no idea if it is even compatible ... but it is portable with a battery and i think also a car cig lighter so im assuming its 12v.