Television and Home Theater

I just finished replacing both of the IC's on my KP-43T70 tv.  I cannot figure what was connected to CN502.  Right now it looks like its waiting for something to get plugged into it, but I cannot find anything to plug into it.   The Service manual is found here; http://www.techlore.com/download/file/25361-93 .   I was able to get out of the diagrams that it says:

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Hey guys,

I'm new to the forum. I have a question about my family TV, and it may seem a little pointless but bare with me. 

Well, as you see I have a RCA p56812BI. It's a really big and really OLD projection TV. We've had it for around 14 or 15 years. Yeah, I know. I would really like to get a new TV by now, because this one is crapping the bed hard. I'm trying to let my parents know that they need to as well, but they're old enough where they just don't want to buy a new TV.