Thanks for all of the input. A friend sent this to me:
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Remember, each of the 2 boards on this game has its OWN power supply and
loss of either will kill the game. Check the 5 volts on both boards AT
THE BOARDS. Never seen a Pole Position yet that didn't have the power
supply pins on the edge connector burnt...that's definately a place to
check. If that happens you can try running the 5 volts and ground to
their respective test points on the board and see if that helps. Better
yet is to connect both boards together and feed them power from a single
switching power supply, but that isn't really needed. If the stock power
supplies are running (good chance) they will do the job nicely. Installing
extra fans in this game is a good idea (one machine I had had a fan mounted
on the card cage to cool the main boards). The power supplies could use
a little extra air, too.
Get 5 volts to the boards and they should work just fine.
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Worth a try at least!
-Tom