It is not going to work unless you have audio outputs on your TV. Attaching an RF modulator into your TV's audio inputs will not make them out put any audio signals. There is nothing to figure out. You need a TV with actual audio outputs.
Joe do you have a cable box? If yes does it have RCA out put jacks? Even if you don't have a cable box you can take the RF coaxil cable either from the wall or from the cable box and put that into you modulators RF in and then out to TV. From the RF modulator RCA output send L&R audio cables to the reciever TV in. Let me know if it works.
Berny, thanks for your help. Although I still think there is a way around this. (this same TV had sound through external speakers through a VCR - but I no longer have the VCR).
Casey, No I don't have a cable box. That is pretty much how it is set up now. I have my coaxial cable from the wall to the RF Modulator and then out to my TV. The L&R audio cables are coming FROM my RF Modulator OUTPUT to my Receiver IN.
Still no good.
Why would this work through a VCR, but not the RF Modulator?
