Contrast control mod for FADA (rca 630ts clone)...
https://imgur.com/0pAv0eh
this circuit was literally copied from the CTC-16/XL.
The same appears in many other RCA color sets with only slight variations.
The FADA has a 330 ohm resistor to gnd on the video output now, I see no reason why putting this in won't work as it does in the color sets, (just have to find s 330 ohm pot ), giving it a REAL contrast cont, and not what it has now, an adjustment for RF/IF gain that has an affect on both picture and sound.