So it's unlikely you can connect coax from Comcast today. There are many web pages on that so I'll stop here.
But then you put your cable box through a VCR so that's a mess. I would not be able to tell if you had old Standard Definition through that or how to wire that up. Let's just say that's a mess without any easy answer as I don't see the VCR. Most are old analog and would connect with the usual red white yellow RCA to the TV and then you select the composite (not component) input on the TV.
"I've spent a couple hours trying everything I can think of and have had no luck getting a single channel. Everything says weak or scrambled signal."
If this was on COAX, that was expected. Here's a web link about the change.
http://www.engadget.com/2013/04/15/comcast-encrypt-basic-cable/
That was 2013 and now it's 2015. Welcome to the machine.
Bob
My mom gave me a Samsung LCD TV (LN32C350D1D) to replace my old analog TV. That old TV was connected to Comcast cable via a RNG110 HD Digital Set Top (aka cable box) through a VCR.
Is this new (to me) TV even compatible with this cable box? Does it even need a cable box or can I plug the cable line in directly to the back of the TV?
Perhaps I need a different cable box?
I've spent a couple hours trying everything I can think of and have had no luck getting a single channel. Everything says weak or scrambled signal.
I am clueless and about ready to give up on the TV. Can any patient person help me out, shed some light on any of this? For starters, are these two devices (tv & cable box) even compatible? Thanks for any help.

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