(Topic ID: 262127)

Eight Ball Question getting Solenoid to Fire

By jrp758

4 years ago

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Latest reply 4 years ago by barakandl
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Eight Ball Bally, 1977

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Question fro all the Gurus out there. I am restoring an Eight Ball Pinball machine.

I cannot get 1, 3, and 7 solenoids to fire. I have changed the MPU and Solenoid driver board. I cannot get them to test fire. I know the solenoids are good. Anybody have any ideas? The Pins all look good and I traced the wire continuity looks good. The test mode does not even seem to send the fire signal to test. Getting stumped and frustrated. 1 is the ball return. 3 is the left side ball saver and is the music chimes.

Any help is much appreciated.

Broken bus wire under the PF? Did you check that the non working coils have 43vdc on each lug?.

Besides that momentary solenoid data connector with a broken contact seems likely.

Check connector MPU J4 pins 1-4 and driver board J4 pins 3-6.
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Comparing the 74154 datasheet truth table to the coils not working could probably identify which of the ABCD pins has a problem to result in those coils not working. Another check would be to put the game in solenoid test and watch the ABCD momentary data right at the 74154 chip on the driver board. If one bit is always high that is the problem signal.

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