Probably too obvious, but you've asked at AMS/Neve? I've never come across a complete schematic I guess. What's the problem, chances are good that it is a psu and / or wiring issue.
I am 99% sure there isn't one. What's wrong with the unit?
quick fix is clean and reseat contacts of the cards. then PS caps. If it's digital garbage, it may be a tough one to fix without
sending it to David Kulka here:
http://studioelectronics.biz/
with digital garbage it will be 3 things. The easiest fix is to clean all contacts. Then replace ribbon cables.
Power supply caps, if old should be replaced, but this may not help digital issues. Then lastly are the RAM and "CPU" cards.
You may be able to pull some ram cards to see if that is the problem. Maybe vary RAM configuration to get one channel quiet.
The RAM cards are the ones with many ICs. The "CPU" card is usually just replaced if possible if that's the problem.
Good luck. These are tough units to fix or find people to fix.