Just picked up a Grand Prix that was not working. Found pinrepair.com and went through the basics of EM repair before you turn the machine on. True confession I turned it on before I found that website and the score motor ran continuously. After going through all the score reels and filing the switches and cleaning and lightly sanding the steppers, the game scores reset and it starts a game. I gotta say this was extremely gratifying.

Now whenever I start a game it seems that most coils are firing except for the c and d reset coils. A and B will reset once both are knocked down. However whenever I manually knock down c and d the machine begins continuously trying to reset A and B even though they are both up and C and D aren't moving.

I may be in over my head here, but I figured why not try to bring a great game back to life.

Any thoughts on where to check next?

Thanks in advance

Travis

Awesome thanks Mark! again noob here. are these switches on the score motor in the bottom of the cabinet or up on the coil mech?

Thanks Mark! going back out in the shop to see if i can make some more progress this evening. I'll keep you posted

Couple swipes of the sandpaper and now its working like a charm! Thank you sir.

Now I gotta get it to move to ball 2 when it drains

alright spent the last two hours going through the entire playfield and mech panel giving every single switch a little sanding. didn't try to make any adjustments because they looked like they were in good shape just gunked up from sitting for years.

i know this is a really dumb question but the game has no coin mechs and had credits on it i suppose when i got it which is how i was able to start games. now it does nothing when i push start. how do i put it on free play or add credits? there is an easily accessible credit reel that i suppose could just be turned, but is the coin unit on the mech panel where I should go?

Well. I manually hit the reset relay and outhole relay while the game was on and got the flippers and pops to work, but I still don’t know if it started a game. The score reels are registering switches/scoring but my eject holes are not working and my drop targets aren’t working.

Also there is a loud hum coming from the one of the steppers on the mech panel. Maybe that’s not normal, but it’s been doing it ever since I got the game.

Currently when I power on the game and hit the start button the coin relay and reset relay lock on but nothing else happens.

If I’m reading this correctly it seems my score motor is not running during the start up process.

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That’s fantastic. I’m going to catalog all the issues tomorrow. Thanks.

You are in no way hijacking this thread. It looks like you've already worked through most of your games bugs so please stick around and provide any info that you think would be helpful to others trying to bring these games back. That video above posted by mrm_4 is great. I've seen lots of that guys stuff previously, but didn't know he had one dedicated to grand prix.

Currently I'm cataloging issues, but currently can't get it to start a game so I'm literally at square one.

update. When I power the game on the lock relay energizes. I believe this is normal.

When I hit the start button the credit reel steps one time and the coin and reset relays energize. Small coils on each of the bonus units also energize but I’m getting no score motor activity.

Going back to the schematic. Any thoughts appreciated.

I did figure out that it is not set on FreePlay and I have to manually advance the score reel to add credits.

Yep. It works. Not an issue on mine but it works

Ok. So I manually turned the score motor with the machine off and now when powering on only the lock relay energizes. Nothing happens when I hit start button

Not sure what I did but now the score motor seems to be running and a game was startable

OK. Powered off and back on and it started a game again. I’ll go through and catalog the issues.

Ok this is after start up. Score reels reset and it kicked the ball out into the shooter lane. I haven’t done anything and it looks like the spinner lane lights are illuminated randomly. Which lights are supposed to be on at start up?

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Gotcha.

So I think I know what i did to get it working. In all my clean up i didn’t brush/sand the pin on the score motor jack. But from removing it and replacing it a few times I think I made that connection better. Is that possible?

Long list of issues to follow

Slingshots work. But score no points. Is that correct?

Advance Right bonus switch worked when closed but only scored 400

Similarly, the advance Left bonus switch worked but only scored 300

Right bonus hole kicked the ball out but scored no points

Right outlane switch advanced bonus but scored no points

Outhole doesn’t kick the ball out when it drains nor does it move to ball 2

HowardR gave me something to try above

Same player shoots again is lit on startup

Chimes sound like garbage and don’t work consistently

Are chime units on EMs from same manufacturer interchangeable?

I’ve got a couple hours later this evening to do some more work. I’ll probably go through and be sure all bulbs installed are good so that I can better identify problems.

That’s hilarious. Good to know I have some options.

Wow. It’s a little intimidating for sure, but the kind folks on here make it a little less so.

So neither side advanced the light when spinners were hit. I cleaned up both ministeppers and now they both seem to be working.

Progress.

Jimbo lending a hand

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I was wrong, the loud hum was coming from the lock relay. Since it’s always on, I removed the spring and now it’s much quieter.

How do you switch these red arrows? I checked the bulbs on the right and they work. I suppose I don’t understand the rules of the game yet, but with all my random hitting and messing with things I would’ve thought that I would have tripped the right arrow by now.

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What does this rollover switch in the top left lane do? When I roll over it I can’t tell that it activates anything.

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OK. I think I’m calling it a night. One last question.

While testing the game, the saucers (top 5000 and right and left bonus) and the drop target reset coils stopped working for no apparent reason. This happened earlier and when I powered off the game and powered it back on the problem was solved.

Thoughts?

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False. Still flaky. Ugh.