I recently acquired a Commodore SX-64. It powers on, but the CRT just displays a white screen. I dont have a test cartridge yet, not that it would help as thereis no display. I havent tried an external monitor yet, but I will. I was just curious, assuming its just the display, is there a command I can type that would play a sound? Then I could tell its booting and I need to fix the CRT.
Just in case you are unaware, there are CRT controls hidden behind the panel on the right side. There's also a floppy reset button and volume control. I don't suspect this will fix your display but might change what is shown.
Shortest command I'm aware of to make sound output:
10 POKE 54296,15:POKE 54296,0:GOTO 10 RUN