Bally Star Trek

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Some of you may have read about my Star Trek switch problem. Many switches fire unrelated solenoids, and the out hole switch resets the MPU like the slam switch.

Tonight I found out that if you manually press the coin door slam switch, and then wiggle it a little, the display will go from switch 2 (coin door slam switch) to switch 8 (out hole switch). That explains why the out hole switch resets the MPU like a slam switch.

I clipped the cap for the slam switch, with no change. And the main wire loom seems to be fine. Which connection on the mpu is where the switches plug in? That's the only other thing I can think of.
 
J2 on the MPU is the connector for switch strobes and returns.

At this point I would disconnect that connector and manually test the switch matrix by jumping strobes to returns. I wouldn't be surprised if you had a board problem like a bad PIA or something. Either way... you need to determine if the problem is with the MPU or the playfield wiring.
 
My first thought was the MPU was bad. It's a Alltek Ultimate. And when we put my techs repaired original MPU in, the problem dissapears.

I called Alltek, and David(?), said he doubts the MPU is bad. He thinks it's just reacting differently to a playfield/wiring problem.
 
My first thought was the MPU was bad. It's a Alltek Ultimate. And when we put my techs repaired original MPU in, the problem dissapears.

I called Alltek, and David(?), said he doubts the MPU is bad. He thinks it's just reacting differently to a playfield/wiring problem.

You could also check the playfield switch matrix at the MPU connector with a meter set to diode check. That should give you a better idea of what's going on with the playfield wiring but it's going to require some more brain power to figure out.

I would still run through the switch test on the MPU manually with the playfield disconnected regardless of the manufacturer of the MPU. Then you'll know what you're working with. It's still quite possible there's a bad PIA on an ultimate MPU.
 
I'm gonna try running the switch test tonight, but I have never done it this way before. I assume I am just jumping pins at J2, but I am schematically illiterate. Could anyone use the crude picture I made below to tell me which pins I need to jump?
J2.jpg
 
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