Spiny watchman fd-20a video cable help

[Kawooa]

I have two new to me fd-20a's. They work great. First one I bought was $7 with no battery holder or case untested. That works great using 6v input. Next was a great find. $15 with case and battery holder. And in fantastic condition. I bought a av cable to 3.5mm plug. It's a standard yellow white red composite cable. I can when connecting it up with the left audio(white) to video(on the DVD player). I get video that way after ground is connected. But I cannot in any connection get audio. Only video. I'm using some alligator leads to connect it up and also some multimeter mini grabber as my third lead. Does anyone have a cable which does work or know of such? I want to mess around and watch video on it. Yes I know. It's a stupid idea but I want to screw around. I enjoy watching DVDs on my commodore 1701 monitor but I want to try something else. And plus this can be useful as a portable video player with my DVD player. If I ever hack that to run off batterys. Thanks for any help.