I'm also under the impression that the grounding on the Polysix is problematic (or better: can be problematic). That this must have been an issue at least for the early units is clear from the technical notes in the service manual. The various problems I've encountered with different units are at least in part grounding related. I can't really make sense of everything yet so I'll run a few more tests once I have a bit more time.
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Re: [PolySix] Better Grounding and the KiwiSix grounding recommendations?
2018-04-07 by Malte Rogacki