linking 4 sega super GT racers together

[theyangman]

So I finally have all four of my sega GT machines in the basement. This took me forever to get from the garage to the basement. But I finally am ready to start linking these machines together. Now here is a little background

I bought two different twins. They were never originally all linked together, so this will be the first time.

I have gotten both masters to work if they are set to singles and they drive just fine.

This is where the issues come up.

When I link the second machine up, everything sounds good, but no picture. The machine sounds like its on, and all the appropriate fans and such turn on, but the board doesn't light up, (there are little leds that dont come on, and the transmit and receive optical slots do no light up either.

No biggie, so I swap in the second slave, and the exact same thing happens. The machine gets power, (I know the monitors are working as they both get the neck to glow when i look at it from behind) but how could both slaves now not be working?

I connected all four hook ups in the coin box, and the optical cables are linked properly, but nothing. What could be going on? Any tips or hints at what I should be looking for?

[theyangman]

Oh and I replaced all the optical cables too. But I have tried with the old ones.

The main thing I can see is that NEITHER of the two slaves have the transmit optical port lighting up to send the signal back. Am I missing a connector somewhere?