Commodore VIC-20 problem BLACK SCREEN

hi, I just found a old commodore , but switch power on do nothing , i checked the main power fuse, the internal fuse all good , still no red led on , i change the led and finally see a bit o life, but still no screen , if i connect to RF modulator only lines and static, with Scart cable , black screen and nothing else , the chip after a couple of minutes became hot but not too much , i just reseated all the socketed chip but still nothing, anyone can help me?
thanks a lot
(sorry for bad english , italian here!)