Hi everyone, I'm making this post just to memorize and help those with a similar issue.

While upgrading a colour classic with a mystic upgrade i got a Bus error message before boot, i could not really work this out, and swapped memory, bluescsi, motherboard and CPU, and nothing changed the error message.

then I found my analogue board is the REV-D version, where the ID pin settings are different from the B and C revisions, I have swapped the pins around and:

Added 4K7 resistor from Pin 3> pin 20 Isolated pin 20 and removed the previous ID settings.

needless to say I have re-capped both the motherboard and the analogue board before doing this.

once I had done that the unit booted and the message was gone. lesson learned here is that a "system Bus error" can be caused by not having the correct ID settings after your mystic update done.

Hope it helps someone in the future!

As far as I know, on updated Mystic Color Classics, the bus error can be fixed. If you correctly configure the analog board ID pins.