Genesis adapter cable constant random inputs plus PlayStation 2 issues.

[voluptuary]

So I bought several DB25 adapter cables for all of my many retro systems so I can just swap around one "core" unit to all of them and not have to worry about repairing controllers every time I change systems. Anyways, they all seem to work fine except the Genesis adapter I have. If it is plugged in to both 1p & 2p (or just 1p) and the system is on but the "core" is not plugged in it starts putting out phantom button presses after a few seconds. If the core is plugged in with the universal HW1 firmware it is fine. If the core is plugged in with the PS2 specific HW1 firmware it also does the phantom button presses but they happen immediately instead of after a few seconds. I actually would prefer the PS2 specific firmware to work with this because the universal firmware requires me to power on my PS2 and then plug in the adapter in order for the controllers to register. I don't know if these things are considered "normal" behaviors or if I have a faulty adapter, and if so can it be fixed? I am pretty handy with a soldering iron but terrible at reading electrical diagrams\schematics. If the adapter cable is functioning as intended is there a way to adjust the universal HW1 firmware to work with the PS2 so that it recognizes controllers if connected at power on instead of having to connect after the system boots?