I replaced the 76477n chip on my Midway Space Invaders board to fix the missing Space Ship sound. It worked great for a week and now when I turn on the machine it has a real high pitch but then after it warms up it start lowering and going up and down but not really like it should sound. I did have the machine running without the speaker connected while I was testing out the monitor, would this have messed that up? All the other sounds work great.
