I've seen several Centaurs that either don't have the triac or have it bypassed. On one Centaur the triac was missing and there wasn't even a hole for it on the rectifier board mounting plate. So the PS in that game probably came out of another Bally (EBD, Xenon, etc). The owner didn't know that the PF GI is supposed to flash instead of stay on constantly.
The way the PS wiring harness is made, you can pull the two molex connectors that go to the triac, then take the two connectors from the harness and plug them together. This bypasses the triac, making the PF GI light up continuously, just as it does in most other Ballys of this era.
But you lose a lot with the bypass. One of the coolest features of Centaur is that the entire PF goes dark momentarily whenever a ball fires out of the launcher. So in the dark you can't see to play any balls that are already in play.
It's easy to tell if the triac circuit's working properly. On power up the PF should be COMPLETELY DARK, no lights, until the MPU completes the seven flash power up sequence.