looks to be a higher end tv from the era. external speaker outputs, multipul RCA jacks and what looks to be a pass through coax for recording. The one connector I cant identify is the almost SCART looking one.
The digital RGB theory is my best guess. It also might handle composite video in and out, as well as mono in and out. It's highly unlikely that it's analog RGB, but without seeing a manual, it's tough to know for sure.
Well, you guys answered the question pretty well, but I had to google some more since I was curious about this oddity. I found this site with more pics of the tv. The model number is 685-2220. I couldn't find a manual online.