William's Gran Prix 1976 EM
The machine was gifted to a family member in a different city.
I don't have access to it until my next visit.
The current problem, I think, I foolishly didn't make a video,
is that when the ball falls into the top eject hole, the scoring motor starts and doesn't stop.
I think the bonus unit counts down correctly.
To prepare for my next visit and repair session, I am currently studying the schematics, and
this is how I interpret what I am seeing.
1. The ball falls into the top eject hole and closes the "top eject switch".
2. The closed "top eject switch" latches the "top eject relay".
3. The "top eject relay" energizes the "top eject coil", which kicks out the ball
and turns on the "score motor".
4. "Score motor" cam 4 switch D, "Make Break 4D", should pulse the "top eject coil" and
the left and right bonus score units.
If I remember correctly, the ball did not eject, so this is where I should look
first for a faulty switch.
If the ball does eject, I should check again to make sure the bonus score unit
zero position switch is working correctly. I think I already checked this.
Does that look right? Any other suggestions?
Does anyone have the equivalent of a "logic probe" that you hook up to relay contacts
to get a visual display of "energized"? Multimeter response seems slow for this.
I guess any 24v AC bulb would work.