neogeo joystick old
neogeo joystick new
saturn vf stick
dreamcast arcade stick (with+green buttons)
gamecube soul calibur stick



and my home-made arcade-system




when i play mvs (neogeo) games, it's all ok
when i play cps2 (6 buttons) games, it's all ok
BUT
when i play naomi with sega IO (jamma)
the dreamcast and gamecube stick have big troubles
i go to test menu to understand, in the IO,
i can the binarie status of the joystick
same bit is already on, when a push 2 button, some direction
is on.
when i connect the saturn vf stick, it work fine, perfectly.
i understand is because of the joystick inside pcb
how to correct it ?