I have a Sony Bravia KD-49XE7002, also tried it on a BENQ GL2450.
My setup for it is this:
SNES -> RCA cable -> RCA/SCART Adapter -> OSSC
The RCA and Scart adapter I’ve been using in the past with an older TV which had a Scart socket, the RCA cable I had plugged into my current TV which also worked.
If I unplug the video RCA (yellow wire), the display says “No Sync” which is what I’d expect to be honest.
Thought I’d also test the Yellow in the Y port while I was at it to see if I got a black on white picture on that, and I do.
My sega saturn works with it.