I aquired a medussa Pin from a Neighbor and it seems to be in good condition.
I replaced the MPU as there was a lot of corrosion. Much more came to life!

First Main issue was a right botton flipper- replaced Coil.

Now if I hit the right flipper it will cause a shut down on most of the game including mpu, but not the flippers. this can be the first hit of the flipper or a subesquent hit- (random)
Also the right upper flipper will not stay up when right flipper button is held down.

I tested the Voltage on the Replaced coil and will get a spike into the upper teens on the meter at random.

I also tested the voltage on the Solonoid Driver Capacitor and I do get 10 volts. (if I am checking it correctly)

Any help is appreciated.

Thank you.

P.

It sounds like your Medusa has power supply issues, with perhaps a ground problem and some flaky connections thrown in for good measure. Driver board capacitor C23 and the rectifier board diodes can both cause game resets as described.

http://www.pinrepair.com/bally/index.htm

See: 2. Before Turning the Game On:

The game is 30 years old and most of that needs doing anyway. at least the power supply, driver board, and connector repairs.

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"Knowledge is Good." - Emil Faber