Does anybody know much about Triacs?
From what I can read they control GI and make them flash, are prone to fail, are no longer made, and are "easily" bypassed.
My questions are...
Does a Triac work with an Aux. Driver board? Does it require both?
Is there anything that can be used to replace a bad one?
What happens when a Triac goes bad...Do all GI lamps stay off?
And how are Triacs bypassed?

So the triac, being a switch, is turned on and off by the small square Aux Driver board? If the triac goes bad, does it stay off? No GI?

Great info. Thanks. I think I have triac issues on both machines.
On Pac-Man, the GI stays on for the pac-maze.
And on Gold Ball the backglass lights are always out. The playfield lights work and blink as they should. There are 2 Triacs in Gold Ball. I'm guessing one for pf and one for bg.

Does anybody know how to bypass a triac so I can see if the lights turn on?

Cool. Thanks Inkochnito. Will try that

Just did a search about Triacs, and see a lot of the same type of posts about Triacs not working. And I seem to be having trouble with both of my games. I just figured they were prone to fail. Maybe I jumped the gun on that? Are they reliable? I don't know

I took pictures of my boards in my machines. So looking them over, I found this. A broken wire in Gold Ball.

IMG_20170226_050007 (resized).jpg

So I checked it out. And a quick fix = Backglass Lights!!!
And they flash when the gold ball comes out. Turns out, it wasn't the triac! One fixed, now on to the other.

IMG_20170226_040122285 (resized).jpg