(Topic ID: 210194)

Bally -35 MPU Boot/Stability (?) Issues

By spiroagnew

6 years ago

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56 posts
10 Pinsiders participating
Latest reply 5 years ago by ArcadeWhisperer
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KISS Bally, 1979

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Question. Have you looked at the driver board? Has the 5V section been tested?

If the 5V on the driver board is not stable nor will the logic on the MPU. If it drops below 5V the game will reset. If it is above 5V it will cause the chips to overheat. The 5V is derived from the 12v from the rectifier. If the regulator circuit is working correctly you should have a smooth 5V.

At this point I think your transformer and rectifier are probably good. The lm323 5V regulator in the SDB has a tollarance of 1%. This means the voltage on TP1 and 3 if tied together should be no greater that 5.05V. Has any other work been done to the driver board?

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