JP15: electronics, change pickup, buffer/boost bypass?

I was playing my JP15 seven string yesterday again alongside my Les Paul (Lindy Fralin PAFs) and my N4 (CrunchLab). I’m still not sure if I’m happy with the proncounced mid hump of the bridge pickup of the JP15.
It’s almost “scratchy” and even trying to adjust it with an EQ before the amp doesn’t quite do it.

So I’m back to maybe trying to swap the pickup (love the neck Illuminator).

Does anyone have instructions and/or schematics of the electronics?
And I’m also wondering what the impact of the active electronics/boost/buffer is. Is there a simple way to bypass it at least for testing purposes? Or maybe a simple way to bypass everything. I’d be willing to let go of the piezo also if need be. Maybe a bypass switch in the back or using the volume pot as a bypass is head of the boost?