I thought of building a switcher for the JV-1010, but bought a JV-2080
instead.

Pins 19 & 20 are vcc. 9, 10 are ground. I assume you would need to switch
all wires.
The pinout is as follows:
AN0,1,2,3,4,5, Sense, xrst, Dgnd,Dgnd, DACA,DACB,DACC,Sdata,
sck,clk,Rxd,Txd,vcc, vcc

Part # of A70 connector is j3439157 (for second board)