i acquired a Grand Prix, hoping to fix it for the owner. I had also hoped i could fix it on my own lol. now Im asking pinside for help.

it seems to have been hacked in very poor ways, which may add to my confusion. there are many issues, but the first i ask about is:

when credit button is pushed, game does not fully reset. if i manually engage coin relay, play field powers up. any hints as to why coin relay and credit button do not connect?

other issues ive found:
ball count unit does not fire at all.
occasionally left spinner shuts off play field. after ball is ejected, play field is energized again.
scores do not reset when coin relay, player reset, reset or ANY other relays are engaged.

thank you in advance.
-barry

Scores do not reset an Playfield does not energize. Ball does not eject.

I'm getting about 16 volts.

I have a hunch it's my credit unit switches....Need to find out which normally closed/open. If I engage game over relay and then manually engage credit unit, Playfield energizes.

Score reel don't reset still tho..

The credit unit seems to have been fixed by cleaning all Jones plugs thank you for the advice
The ball count unit is my next hurdle. It never energizes. I will start a new thread for that tho..
Thank you pinside. You're always helpful