on page 19 it shows the chain of harness wiring to transformer to jack board. Basically you just cut out the transformers and plug the input to the transformer directly into the jack board.What I am referring to is the transformer board listed on page 16&17 of the Aero City Manual
https://wiki.arcadeotaku.com/images/e/e5/Sega_Aero_City_Manual.pdf
There is also a write up by random retro about this.
https://www.arcade-projects.com/threads/jnx-sega-839-0158-repro-headphone-board.2256/page-2
I never got around to installing it because of that transformer board.
Huh, yeah I guess it could be. I thought it was original stuff but maybe it's that?This is what he's sellin