I bought a C64c. It has a power supply, but there are only four pins on it which may or may not be suspect. The computer LED comes on. I connected it to a TV with an RF modulator. It's an Atari modulator, but I guessed it might be okay to use. The output, however, is a solid gray screen. (I don't have a monitor, otherwise I'd try that!) I don't mind if I bought a project. I'd like to try to troubleshoot the problem. I have a logic probe, a multimeter, and have some soldering and desoldering experience. Can anyone give some tips on what to check?