Hey guys, it's been awhile since I've worked on any Macs. I have a Macintosh 128k (later revision board) that will chime but not show any video. I've tested the board in a known working case. When I first opened it up the board was slightly corroded, and after an alcohol wash it still doesn't work. Any ideas what the issue could be? I'm not sure what part of the board controls the video signal so I can't go around testing components just yet. Thanks!