Quoted from coz6:By the way it was already replaced (not the original orange one) should both sides have voltage?
One side of the +5V bridge is connected to ground (the frame of the transformer unit). The other side is something like +12V DC. You can measure both across the bridge, or the terminals of the big cap on the transformer unit.
The 80B cap isn't orange from the factory, so just because it's not orange doesn't mean it's new. 1980s caps are bigger than 2014 caps. Replace with one that looks smaller than pictures in pinwiki.
I like the idea of bad ROMs. Try the known good CPU with known good ROMs in the wrong game (with the driver board disconnected).
Measure DC across the big cap on the CPU board near the power connector. You should get about 5V (a little less is OK). Measure AC across the same cap. You should get a near-zero, but not quite zero, reading.