Question about mux-ing the brook retro board with a genesis controller PCB

Tech Talk
1

I am trying to make my arcade stick work for both the Brook Retro Board and a soldered Genesis PCB.
I am using a 20 pin 3-way Mux to splits the button cables into 2, so that I can connect the Brook and the Genesis PCB simultaneously to my stick buttons.

However, the Genesis PCB seems to not work (no inputs are registered) when the Brook is also connected to the Mux, even if the Brook isn’t connected to anything via RJ45 (so it’s offline).
This baffles me as it works fine when I remove the offline Brook’s connection from the Mux.

Does anyone know why this happens, and if it is even theoretically possible to do what I suggest in the first place?

2

Few things we need to look at first.

Is your Sega Genesis PCB common ground or not?
(Meaning all the buttons share the same common ground or negative voltage Return line)

For your Dual Mod, do both boards share Power and Ground?
You need this in order for this to work.

I suggest searching and reading up on Dual-Mods on SRK Tech Talk.

3

Thanks for the kind reply.

Yes, the genesis PCB has one line for each button and has a single all-connected ground as far as I can tell from eyeballing it.
So I soldered all the 3 ground pins of the 20-pin ground lines to that single ground.

I don’t quite understand your remark about the boards having to share Power and Ground…
All I know is that the boards have 2 different connectors (the brook connects to, say, the SNES, and the Genesis PCB to the Genesis) and I only connect 1 at a time, so they are never powered both at the same time.

Do you perhaps have any link to point me to?
I’d love to know more about this stuff and I’m just starting out :slight_smile:

Thanks for the info :smiley:

4

The golden rule of dual-modding is “all pcbs should be powered at all times”

You need to tie the vcc and ground lines of the genesis pcb and retro board together otherwise you can get some pretty unpredictable results. Just remember never to have your stick plugged in to 2 consoles at the same time.

5

Also doesn’t dual modding cause more problems than a discrete vbulk pin swap un/ swap out? Now here are 3 possible errior places, board a, board b, or issues when electrobunically tying them, separate bulk pin discrete wiring is best defense against a/b combos. But you have to have more electronic.

That’s why Stan is the physical wirer and I found a simple yet versatile setup. I ran this design with SRK experts, an do be at least half say if a newbie can explain pathways through video game/movie rca hookups as the most experienced thing i can fix diy then i can probably diy fix it myself sply by rerouting.