Robert:

Most RGB-capable systems use either sync-on-green (where a composite sync pulse is combined with the green channel), or have a separate sync channel or channels. Some (now very few) systems used a single separate sync channel, called "composite sync" because it included both the horizontal and vertical pulse information combined. It's basically the same sync information that's found in composite NTSC video.
True component systems (Y/R-Y/B-Y) have composite sync on the Y (luminance) channel.
S-Video systems have composite sync on the luminance channel. That makes the luminance channel of the S-Video signal simple black & white video.
The more common separate sync channel format found in RGB systems uses completely separate horizontal and vertical pulse channels. So the system would include 5 connections: R, G, B, H, and V.
If your system has no input for sync, it uses sync-on-green (if it really is RGB; check to see if it is really Y/R-Y/B-Y). If there is 1 sync input, it uses composite sync. If there are 5 total inputs (RGBHV), it uses separate everything.
Now, as far as your "funny square-looking connector that has angled pins", I have a guess: It could be the old EIAJ connector found on many old Sony U-Matic VCRs and some TVs. If so, the signals are NOT component. This connector was used to make connections simpler between a VCR and a TV. It includes composite NTSC video and two analog audio channels on an 8-pin connector. Not all of the pins were used in one direction, of course. This connector was capable of being used in both directions, having 2 video coaxes and 4 audio paths. The ground/shields were partly in common, as I recall, which allowed this.

DennyD1@aol.com