Connecting a combo DVD/VCR player

[feldmanr42]

Trying to get an old DVD/VCR combo player to work so our grandchildren can enjoy our library of Disney VHS tapes. The old RCA DVD/VCR combo is now connected to the Vizio TV using the composite cables and a coax cable since the back of the RCA unit says the only DVD/VCR output is thru the coax. The label above the component output states it is for DVD only. I used the Comcast Remote Control to switch the input source to "AV". I can now play a DVD using the RCA unit with no problem. However when I play a VHS tape I am only getting the picture, no sound. Any ideas?

 

[rgd1101]

MERGED QUESTION
Question from feldmanr42 : "Connecting old RCA DVD/VCR"

I have an old RCA combo DVD/ VCR player connecting to a Vizio TV. The back of the RCA has a single output labeled for "DVD/VCR out" using a coax cable. I have also connected the 3 component cables from the back of the RCA directly to the Vizio, although the sign above the component cables says it is for DVD output only. Using my Comcast Remote Control, I have changed the input source to "AV". I am able to play a DVD using the RCA player just fine. However when I use the RCA to play a VHS tape I am only getting the picture, no sound. There aren't any additional outputs on the RCA labeled specifically for the VCR. Any idea what I need to do to get sound???