I saw a how-it-works article on that model Sylvania console in a magazine (Popular Science, perhaps) in the early '70s, but have never actually seen one of those sets up close. The set used a color flying-spot scanner with three photomultiplier tubes to create a video signal from the slide image, which of course was treated by the TV as if it were an off-the-air color signal (only the outputs of the phototubes were fed directly into the video stages, completely bypassing the RF signal circuits). This was such a great idea at the time, IMO, I'm amazed other manufacturers didn't pick up on it and offer their own versions.
It would have been a great way to show 35mm slides in a small apartment or any other place one could not set up a conventional projector and screen.