(Topic ID: 88676)

WIlliams EM Coin SET UP- grand Prix

By rufessor

6 years ago

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  • 16 posts
  • 5 Pinsiders participating
  • Latest reply 1 year ago by LoganJK
  • Topic is favorited by 2 Pinsiders


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#1 6 years ago

Ok- count me as completely lost here.

I have a Williams Grand Prix which is a 1976 game and I am very confused about why its working the way it is when I add a single quarter.

The manual (which is all we should need) is available at the IPDB page
I attached a photo of the relevant page at the end....

IF I have the following set up
1 coin- 1 play/2 coins- 3 play jumper in the OFF position
5 c adjustment in 2 coins (think this is irrelevant)
10 c adjustment in the zero position or basically unplugged
25 c adjustment in the 1 position (with the bottom legs of the plug hanging off the end of the jumper and not engaged- but they are not wired anyhow)

When I drop a quarter through the coin door, with the game in a ZERO credit position on the credit wheel. The following things happen

The credit unit DOES NOT INDEX UP-
The PLAYER unit indexes up by one, its as if you indexed the credit wheel to 1, and hit the start button to use that credit to start a 1 player game.

If I then add another quarter, it simply ADDS a player.
I can keep going until I exceed 4 players and nothing much happens- you do not begin to get credits

IT SEEMS LIKE THIS IS WRONG... but it works so well, its almost like its supposed to do this. WHY is it adding players and starting a game automatically? Why is it NOT adding credits?

So for additional data points- I tested its behavior under a bunch of other settings and to me, it works as expected under every other set up I tried... so here is what works... and maybe this all means the first part is expected behavior but I don't understand it.

Additional TEST condition 1

If I move the 25 c adjustment stack to the 2, 3, 4 etc position and with the credit wheel in the zero position (moving nothing else) I add a single quarter and .......

I get 2,3,4 etc credits per quarter (depending on where the stack is) and the credit wheel moves the correct # increment up and I start a game the normal way with the start button adding players removes additional credits as would be expected. I view this as fully anticipated behavior.

Additional TEST condition 2

If i move the 1 coin/1 play 2 coins/3 play jumper to the ON position, and as the manual says, then position the 25 c and 10 c adjustments into the #6 and #2 positions- when I add a single quarter the credit wheel increments 1, when I add a second quarter it increments 2, and on the third quarter it adds 1 while the fourth again adds 2 credits.

Again, fully normal anticipated programmed behavior.

So- can someone explain what possibly is wrong with my understanding of the first condition and the, ?ODD? behavior I describe (or is it normal, and if its is WHY). Why is it that adding a single quarter with the quarter position switch in the 1 position, results in addition of players to a game without ever indexing the credit wheel and why is the game "auto started" under this condition?????? - WHY DOES IT DO THIS!


Pic of page is below.

#2 6 years ago

Unplug the 5¢ and 10¢ and see what it does. Too many years to remember, but by 1976 I think you only use one of the three for what coins you use.

LTG : )™

#3 6 years ago
Quoted from LTG:

Too many years to remember,

I'm lucky to remember anything from the 70s.

#4 6 years ago

Will try and report-

I need to pull the 5c plug as I had that one plugged in. But it seems like the subtext to your answer is that indeed this is slightly odd! Had me really really mystified. The manual of course, assumes your a coin pop operator with years experience setting up these things and you just *know*

unless all the invisible ink in my manual that describs how this works disappeared over the last 40 years....

#5 6 years ago

LTG wins the prize-

Indeed- unplug the 5c jumper and a quarter acts like a quarter should. 1 big stinking credit if its in the 1 credit slot... not a started game-

HOW ODDD.... makes me want to look at the schematic but my head hurts from looking at it for other reasons so this may have to remain a mystery.


4 years later
#6 2 years ago

Although this is very old - I did want to offer a shout out of thanks to the contributors of this topic (especially LTG) - I too was pulling out my hair on this same problem with my Grand Prix. I had gotten as far as identifying that the odd behavior was only when the machine was set to 1 credit per quarter and was so happy to stumble onto this solution. Now onto the next issue!

#7 2 years ago

Fun to see this dig up. I was failing to remember when I got this game and this gets me close!

As an aside, EM’s are remarkably reliable for their age. Since this game was restored mechanically (body and playfield only, head still needs to be dealt with), the game has worked flawlessly until a few weeks ago. A switch in the head is stuck. I have not yet ripped into the head but I suppose I may as well just rip it down and restore it.

I do play my games.... so it gets regular use.

Anyhow, an EM will go 4 years trouble free... and that’s not even completely restored! They are pretty amazing..

6 months later
#8 1 year ago

rufessor Could you post of picture of your coin mechs? My machine came with nothing and I need somewhere to start, thanks!

#9 1 year ago

I can do tjis. Gove me a bit and I will post here. What exactly do you need ohotos to show? The coin mecha themselves are obviously stock std and anytjing could work.... do you want to see jumpers? Anyway... lemme know and pics will appear here

#10 1 year ago

It looks like they were ripped out at some point. Will this work? https://www.pinballlife.com/25-cent-standard-coin-mech.html

I'm looking for pictures so I have something to reference. Yes the jumpers would be great.

#11 1 year ago

Probably those work but you will need to get an adapt o kit- the game has a sightly different (not unique) mount where there is a metal clip on the side opposite the mounting pins on the coin mech. Pics are way better than words. Going to get photos today. Willl post all later.

I usually look for old mechs- they almost always still work great (just be picky and ask for photos. If it looks dirty and crap dont buy that one!). You may be able to find someone with clips. I had to buy one for my game. Forgot what they are called but it was not super hard to find. Pics will make it obvious.

#13 1 year ago

Winner winner chicken dinner!

Thats them.

#14 1 year ago


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#15 1 year ago
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#16 1 year ago

Thank you!, I'll update when I get the parts in

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