The sound is way off on my 630TS. On stations with a good picture (i.e., 4 & 5), there's no sound at all when fine-tuned for best picture. There's no channel 6 here, and when tuned to channel 6 on the TV, I can bring in FM radio 89.5 with good fidelity and volume.
I did some voltage checks, and found 0 volts on the plates and screens of the sound IF tubes (V104, V105, V106), which seems puzzling. They are on the 135-volt line, and the power supply is indeed putting out ~135 volts.
I posted the schematic at these URLs for anyone who wants to follow along at home.
http://antiqueradio.org/art/temp/RCA630TSSchematic1.gif
http://antiqueradio.org/art/temp/RCA630TSSchematic2.gif
Anyhow -- the sound section *can* make sound, but where to start? For example, should I investigate T2 converter transformer!
Thanks for any hints!