Ideally I’ll find a TV and a VCR. I can use the TV to test the commodore and the VCR to test the other TV.
Plus the VCR will have RCA outputs, so I can use it to capture RF signals with my capture card.
Of course, that will only help me narrow things down. It is still possible that my power supply for the c64 is bad (it’s a new aftermarket part from c64 forever) or that there’s something wrong with the cable setup I’m trying to use.
But I won’t know anything without more inputs.