Yes, that’s the ‘Joe Walsh’ Alice…… I remember it well because I delivered it personally to Boulder Colorado and was able to ‘hang out’ with Joe and the band.
The channels operate on 15-0-15, I advise against pushing them to 18V, they may stand it but it affects reliability.
The meters are probably 24V, but we always run them on 15V AC nowadays, it makes them last longer.
I’m afraid I don’t have any drawings for that series (It was a ‘Trackplan’ mixer) but the circuitry is very simple…. nothing over-clever…. It was a good design and sounded great, mainly because of the simplicity and plenty of headroom.