(Topic ID: 321217)

Grand Prix: endless bonus countdown

By Richthofen

1 year ago


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Topic Stats

  • 11 posts
  • 6 Pinsiders participating
  • Latest reply 1 year ago by hjh632
  • No one calls this topic a favorite

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#1 1 year ago

I have a Grand Prix and The left bonus countdown is wonky. Sometimes the spinner stops rewarding bonus. And oftentimes the bonus countdown from the scoop endlessly counts bonus. I think the bonus unit needs cleaning but I don’t know how to start. I’m also admittedly not great at the tech side so if you have advice, explain it like I’m 5. Thanks in advance!

#2 1 year ago

I think the left and right bonus units behave the same way so you might start by comparing how they behave. You could queue up the same number of bonus points on each and collect the bonus to see (from below the playfield) how they count down. You could also manually advance and reset each one to see if they behave the same, if the zero position switch opens at the same time, etc. Essentially look for any differences between them.

/Mark

#3 1 year ago

While doing the above as Mark suggests...

I believe the left bonus is the stepper toward the front of the machine. It is prone to being rested on the front edge of the cabinet when the machine is opened. That tends to skew it from its normal rest position (rotates the rivet board) and causes all sorts of problems. Check that first - only takes a few seconds and could solve it, and if not, very little time lost.

4 months later
#4 1 year ago

It actually isn’t an endless bonus countdown. It’s the 500 switches. If I activate either advance bonus switch below the score bonus scoops, they continuously score. The switches aren’t stuck I gapped and checked them. I assume it’s the score / player relay in the head? Is there a good guide on cleaning / maintaining that out there?

#5 1 year ago

If you're saying that the 500 Point relay stays locked on when it should release, I can't find the 500 Point relay coil anywhere on the schematic. Can you?

#6 1 year ago
Quoted from Richthofen:

It actually isn’t an endless bonus countdown. It’s the 500 switches. If I activate either advance bonus switch below the score bonus scoops, they continuously score. The switches aren’t stuck I gapped and checked them. I assume it’s the score / player relay in the head? Is there a good guide on cleaning / maintaining that out there?

This happened to me. If you hit the two slings below the scoops, the motor never stops.
The issue was the wires under the playfield that are on the relay stack hit the top of the stepper unit at the bottom of the playfield.
I found this out because the slings worked fine when the playfield was propped up.
Just bend the wires back out of the way.

#7 1 year ago

The 500 point relay coil is located at A-22 on the schematic. Its shared hold circuit wire R-BR could effect its operation and other relays if its score motor hold circuit release switch 5B is dirty or improperly gapped. Clean and adjust switch if needed.

#8 1 year ago
Quoted from pinballdaveh:

The 500 point relay coil is located at A-22 on the schematic. Its shared hold circuit wire R-BR could effect its operation and other relays if its score motor hold circuit release switch 5B is dirty or improperly gapped. Clean and adjust switch if needed.

Good find, pinballdaveh !!

#9 1 year ago

Are you talking about the 500 point switches that are labeled "advance left bonus" and "advance right bonus" on either side of the playfield about halfway down?

I've had trouble with them, and they have shown up in lots of Grand Prix posts as the roots of problems. They are a funny arrangement of double switches, and sometimes one of the switches is 'making' all the time and causing many problems. Check them carefully and compare and contrast them from left and right side.

#10 1 year ago
Quoted from hjh632:

Are you talking about the 500 point switches that are labeled "advance left bonus" and "advance right bonus" on either side of the playfield about halfway down?

Yes, these are the switches I'm referring to, the "dead slings". I think they're the only thing in the game that scores 500 points.

#11 1 year ago

I don't have the game anymore, so from memory...

Each side of the game should have two separate switches in the 500 spot. Make sure that they are all separated while at rest. My game had one of the switches always touching and caused multiple seemingly unrelated problems.

May not be your solution, but only takes a few seconds to check. I would also manually work the 500 point relay back and forth to see that all switches change state when activated and that switches bump and push each other slightly when closing.

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