One other thing . In my 1st post I mentioned that when the 20 relay trips, the resistance (to ground) on the ground lug of the coil for the bust relay drops by 1 ohm.
I just checked this on my own Lady Luck and there is no change of resistance . Not sure why this happens on the 2nd LL or what it means .

Possibly because we have a cleaner path to ground... but this is a red herring to chase, im sure of it.

My last post didnt make sense.. i had an idea then when i went to post i lost my train of thought.

The key here is the A player relay, but the problem we have is that the ground path for 20 is definately going through this path and to do that 8 or 9 and RO must be closed... all A player does is determine if its 1 or 2 player thats active....mmmm.....

Can you test for continuity on 20pt stepper position and that side of BUST coil.. then 20pt to RO relay.

it should be isolated from both. Do this with game off and then on before game start. Then again once game is registered and ball 1 is indexed.

I want to make sure that its a relay coming over and not a fault that is hard wired.
I then want to make sure that where Ball Index relay is on far left of diagram ( this goes to White with Blue @ 9C on diagram) that its not a fault elsewhere through ball indexing.


Im loving this mate.. waiting on parts to fix my machines, so il do yours instead and its an EM conundrum