Not sure what I did to completely mangle my Core 1 and/or SID 1 modules, but both MIDI comms to MIOS and audio are totally skewed now (UHG!)....
Starting with the Audio Issue...
SID modules #2 - 4 still sound perfectly fine (quick n dirty example below)
https://drive.google.com/open?id=1FcfTqcUriYw4KaTXh1OSesTP9RLqs5_i
...But I've somehow managed to destroy the sound coming out of SID module 1??
https://drive.google.com/open?id=1tYVHFEG5-MbfYCJQZLcDfbC6LaOJ9Hk-
Holy moly... My Core1 MIDI Issues are finally SOLVED...
Turns out I had the wrong sized caps in C1_CORE1 and C2_CORE1 (embarrassing).
This was impacting the oscillator frequency and effectively crippling core1.
I have a big box of MLCC caps, which must shifted around in their compartments.
That will teach me to examine those tiny little numbers better and test each component, before soldering!
So, once I corrected the caps, all MIDI communication though MIOS ar