I bought on sunday a new TV (LG 42LF450-ZA) and connected the Dreamcast as first into the OSSC to VGA and then directly into the new TV. It didn’t solved the problem and it still had these horizontal, wavy square lines.
As you can see here:
When I put the VGA into my previous Toshiba LCD this issue didn’t appear. It only happened through the OSSC with VGA.
However, I could rid of the problem after I connected the audio phone connector to the OSSC <-> TV.
Weird somehow… maybe it has something to do with the shielding…
Everything is fine now and it works