Yes, the left channel Snd chip was out. Replacing it fixed the sound after boot. The distorted chime is still puzzling.
In case anyone comes across similar problems, I'll go into some detail. There is 1 ASC (surface mount, 44 pin sound processor) and 2 smaller chips (DIP16), one for each channel. The silkscreen next to these two DIP chips says Sony, so perhaps Elfen is referring to the ASC as the sony chip. These smaller Sony snd chips convert PWM to Analog signals (low pass filter), and probably amplify them slightly. These DIP chips also have 3 (SV 1:3) lines connecting to the ASC, which must be the volume control lines (there are 8 levels of volume on the Mac, so this would make sense).
I connected an oscilloscope to the PWM pin for both and observed working signals from each while the machine was running.
I've also verified all the connections to these PWM->Analog chips, and all the passive components nearby.
I'll report back when I've finished recapping. Thanks for the responses and interest.
In case anyone comes across similar problems, I'll go into some detail. There is 1 ASC (surface mount, 44 pin sound processor) and 2 smaller chips (DIP16), one for each channel. The silkscreen next to these two DIP chips says Sony, so perhaps Elfen is referring to the ASC as the sony chip. These smaller Sony snd chips convert PWM to Analog signals (low pass filter), and probably amplify them slightly. These DIP chips also have 3 (SV 1:3) lines connecting to the ASC, which must be the volume control lines (there are 8 levels of volume on the Mac, so this would make sense).
I connected an oscilloscope to the PWM pin for both and observed working signals from each while the machine was running.
I've also verified all the connections to these PWM->Analog chips, and all the passive components nearby.
I'll report back when I've finished recapping. Thanks for the responses and interest.