NotTaR of Television Sets : Can I add direct RGB inputs to a TV?    
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Can I add direct RGB inputs to a TV?

The signals going into the CRT neck board are separate RGB, possibly a somewhat higher voltage level, but otherwise similar to those sent to a computer monitor. So, would it be possible to bypass the tuner and color decoding and go direct for better picture quality? After all, RGB SCART inputs are common on PAL TVs.

Assuming the scan rate of your source is NTSC (or PAL as appropriate), in principle, yes. The RGB signals may have to be amplified from the normal .7 to 1 V p-p used for monitors to whatever is required by your TV's final video amps (unless you can find a location on the mainboard where the levels are lower) and composite sync would need to be injected separately.

However, there are some serious safety issues. Many TV are designed with a chassis that is electrically live - not isolated from the AC line so unless an isolation transformer is used to power the TV or some means of isolation is used in the coupling of the signals, you could end up with a very shocking situation and/or blown parts all over the place. I wouldn't recommend it unless you have the complete schematics and really know what you are doing.