I was working on a Macintosh Classic II which had an interesting fault. It was the second time I had fixed it on one and thankfully had notes from the first time.
Symptoms:
When powering on the system you have either no sound or distorted sound. Pressing reset continuously makes it get “better” but never right.
Fix:
Check the resistance between pin 4 and 5 on the 34119, it should be 75k. If it’s say 1M or more, you have a bad connection. Likely due to corrosion. Add a jumper wire to fix.