General S-Video (Y/C) to Composite question

[Rex Dart]

I've been A/V modding the rest of my systems now, and some of them use relatively complicated circuits to mix the chroma and luma signals internally to produce composite video output, compared to other systems that natively output both Y/C and composite from their video chip.

 

The S-Video mod guides I see for these usually involve disconnecting the circuit that produces composite video. I'd like to have both S-Video and composite output, since my goal for modding my systems is both improved picture quality and convenience in connecting them to TVs. Most newer TVs don't include S-Video connections.

 

 

So I know that you can just straight combine the Y and C pins and get composite video, but are there any downsides to doing that? Could this possibly harm the system in any way? I'm just wondering since several of these old systems run the Luma through a mess of resistors and capacitors before combining it with Chroma to produce the composite signal. If this is totally safe in every case, then hell, I'll just add a switch that combines 'em for composite, or rig up some sort of RCA jack that only makes the connection when a cable is inserted.