As high as that? Ouch! It warrants pause for thought, then. My only data of that kind come from PB100 series, the blue 160 inverter board (922-0025) and the green 180 board (922-0024) specifically, which are marked on the boards as 350VAC and 400VAC outputs respectively.
However, my scribble-book reminds me that there are more part numbers for other PBs in the 100 series (699-0273 and 922-0375 at least), and I don't doubt that Apple could have used much higher voltages for later PBs.
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