TL;DR: Power amp relay won't switch, appears to not be getting enough voltage to turn it on. Relay power voltage looks to come from main transformers, but no output from transformers. Curiously, input to transformers looks to be DC, not AC, based on service diagrams as the same circuit runs through the relay coil and the transformers. Relay itself functional. Only obvious issue is failed capacitor (bulging end) in rectifier circuit from standby transformer. Service diagrams available just below the break.
Hello all,
I posted about this a few months back [here](https://www.reddit.com/r/audiorepair/comments/f0w4iy/nad_ci_9120_loud_buzzi