So I have a commodore vic-20 with a faulty keyboard. Im building an arcade machine out of it. I picked up a 1987 Sharp 13" color tv for the monitor, it has a coax input.

Heres the question, or maybe potential problem. Ive read that the vic-20 gives a much clearer picture when using the s video jacks, rather than the coax. Can i just use a standard s video to coax adapter and still retain the better image, or is further modification needed?

Well since ive been bored, ive decided to knock out a little 3/4 size arcade cabinet. I picked up a 1987 sharp 13" color tv with great picture. Its just about perfect for this. The joysticks and buttons wont be a problem, theyre made aftermarket and are highly adaptable.

Since this tv takes a coaxial input, should i run the coaxial connector for this to the vic 20? Or mod the tv itself to be directly hooked up to the vic?

Well tomorrow im going to mock up the arcade cabinet with cardboard, get an idea of what proportions will look correct.

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Going through RF (coax) will negate any advantage of starting from S-Video. You'd need to modify the TV to accept it, which for a set of that era may or may not be possible.

You need to be VERY careful attempting a mod like this.

The "ground" point on the TV chassis is actually connected to one side of the AC powerline (either directly or through one side of a diode bridge), whereas the ground point of an external video input needs to be actual earth ground referenced.

Your circuit would need to incorporate proper isolation (optical most likely) to get the video signals across the potential difference between chassis ground and earth ground. Otherwise, you will have a severe shock hazard, and potential sparks and smoke when you connect an external device to your new input connector.

chances are there is no easy point to inject video if the set uses a "jungle chip". Also, a number of this era set used opto coupling to prevent any chance of grounding the source thru the power supply.Can you post part of the video schematic?