Save help!!!

Hello, All I read the forum and decided to revive my old friend. Scorpio first version, on a yellow (and apparently not branded) board. 2х5.25.Teac and GS to boot, also an old modification, the last time I saw all this was back in in working condition, it stood for almost 4 years... it started and even it worked, the games launch, AY plays, but GS doesn’t work :-( what see where to look? from the symptoms - when turned off from the speakers the sound is like this "vvzhzhzzzz" fading... and fast... the electronics engineer himself, hands to the soldering iron sharpened, but no oscilloscope... I checked the sockets, they seem normal, but what I also could have died there from time to time, I don’t know.. please help me lift the piece of iron!!!