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ChadTower:

--- Quote from: Popcorrin on February 09, 2006, 05:15:29 pm ---Everything was working fine at first but now the bumpers do not work.   From my limited knowledge I understand that when the ball hits the bumper it closes the contact on a leaf switch which sends a signal to the cpu board which in turn tells the coil to fire.  The coils have a power line running to them which I am guessing is always hot and the control line on the coil goes to the cpu board. 

Since all five of the bumper coils aren't working I thought maybe it had something to do with power wire going to these coils, but I really don't have a clue and I was looking for some advice.

--- End quote ---

The closed switch sends a signal to the driver board, not the MPU.  The low voltage signal triggers the appropriate transistor to open and send appropriate voltage to the solenoid which continues to energize until the switch is opened again, taking away current to the signal pin on the transistor, and closing off the voltage to the solenoid.

Are the coils on that machine daisy chained?  If they are I would suspect that you have a broken solder connection somewhere in that chain, especially if some of the bumpers on that circuit (the ones preceding the line break) do work.  Generally such lines have more than 5 things on them up to around 8.
Ken Layton:
Marvin3m.com has a Data East pinball repair guide.

It's possible that you have one of these problems:

Blown fuse for the 24 volt coils.

A power wire feeding one of the other coils on the same circuit has a wire broken off it.

A burnt connector or bad solder joint on one of the circuit boards.
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