it's very possibly a bad dump. it was the first chip I dumped, so I can redump it tonight.
donkey kong's sound is very strange so it's not surprising you're having issues. I didn't fully reverse engineer it I don't think. there's 2 or 3 IOs involved with sound from what I recall, and a mess of resistors and transistors and stuff.
galaxian's sound is weird too.
ms pac obviously normally eats the dots in the top two rows; smells like a RAM banking issue maybe.