Hi all, been working on a Grand Prix all day. I repaired many things. One thing I cant get to work is the Ball Advance. I have the schematic and manual, and even a few extra items that game with the game. I went through every switch, because this machine had some major issues from lack of use, and it appeared to have been in a damp place. I took apart and serviced all steppers. working freely. The only thing I did not touch was any of the switches on the score motor.

The only way to advance ball count is to manually run the stepper. I can cycle this through until the game over relay energizes and ends the game.

When I manually advance the Ball Index relay nothing happens.

Yes I have used them before.

Still not getting it to go past 1st ball.

Coil Checked out good on DMM test

Dam IT!!!!! Some how I went right past the switch on score motor! I will check when I get home from work and report back! Thanks!

I will also try this, Thanks!

LOL

The switches on the score motor look correct, I am really lost as to why I cant get the ball to advance, I don't know if this is related, but the left kickout does nothing, the switch under playfield is making contact....

I will clean and report back

28 alcohol Q-Tips later no change

OK I cleaned the Jones plugs no change. the red start button on door no longer works I can go in cabinet and manually close coin relay to reset and start a game.

I manually apply some points to player 1 ball 1 I notice the Ball index relay is energized, I then manually hit the ball outhole relay, this in turns unlatches the Ball Index relay. bonus score applies but does not advance to ball number 2

Howard, I sent you a PM

Thanks Howard. I have to go to a funeral tonight so will be working on the Grand Prix later in the week.
I am going to kind of stat from scratch and work through every thing again. I was reading some other posts, and I read where someone would use a DMM to check the status of the switches. Good idea considering the score motor switches are a little difficult to see and get to.

Actually I am still new to this so I am finding my process

That makes perfect sense, so a combination of both maybe.
I just have a really difficult time with the score motor switches down in that cabinet so very hard to get a good angle to see, and adjust!

Thanks again Howard for replying, I will keep this thread going until the machine is fixed (I Hope).

Yes I do have the "L" Contact Adjuster.