(Topic ID: 282541)

Bally one switch fires another

By jdrossos

3 years ago


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  • 12 posts
  • 4 Pinsiders participating
  • Latest reply 2 years ago by cottonm4
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#1 3 years ago

Hello everyone. Suddenly as I was playing my Bally Strikes and Spares, I realize that I had a mess with some switches. I hit one and fires another! I looked in the switch matrix but I don’t know very well to read it…. My first thought as I saw that the problematic switches where in the same row, was that a diode has to do with that. So, I replaced all diodes from all these switches, I desoldered the small caps and I looked for something obviously like sorts etc. nothing found. After that I had the same problem. I friend of mine told me that maybe the u10, u11 chips where bad so I replaced them both. Nothing again. Same problem. The problematic switches are the 4 that I marked in the diagram, but in switch test it involves and the credit switch. I mean I push the target and the number of credit switch appears. So, I disconnected the front door to see if the problem was that. Nothing again. Same problem. Any ideas guys? What should I do next?

switch matrix (resized).jpgswitch matrix (resized).jpg

#2 3 years ago
Quoted from jdrossos:

I disordered the small caps and I looked for something obviously like sorts etc. nothing found. After that I had the same problem. I friend of mine told me that maybe the u10, u11 chips where bad so I replaced them both. Nothing again. Same problem. The problematic switches are the 4 that I marked in the diagram, but in switch test it involves and the credit switch. I mean I push the target and the number of credit switch appears.

The row is shorting and the reason only the credit button shows in test is that bally switch test only shows the lowest numbered switch closed.

I assume mean 'desoldered' the small caps, which are likely the issue, if they are original just replace them (all of them in the game....)

Anything change in the game? Have you changed bulbs recently or rebuilt or adjusted anything?

#3 3 years ago

Someone told me that i can throw them away and not use them. (The caps). So for testing reasons i desoldered them. Soldered again nothing changes

#4 3 years ago

Sorry worded that awkwardly - meant the problem is probably related to the caps, leave them disconnected, but plan on replacing them. They are needed for the pin rollover buttons for reponsiveness.

There has to be something that has changed in the game to ground out that row though. Usually the capacitors are suspect right away which is why everyone says to replace/disconnect them first.

Try putting it in the switch test then disconnecting the cabinet switch connector J3 from the mpu board, then test the playfield switches see if your behavior changes.... if it works issue is on the cabinet connections (I know you did the coin door, but there is also a switch cap on the tilt mech.... trying to eliminate the cabinet/divide and conquer)

#5 3 years ago

Thank you slochar! We have a progress here. Every cap from the 4 switches out , put in test mode and disconnected j3 , and bingo! switches register as they should. So what's next?

#6 3 years ago

So, i disconnected every cable from tilt mech and unplugged the door. Problem still exist but i think only between switches #22 and #30 ....
Edit.
one time is working ok and the other not. Now with everything as i said not connected, and problem appears again to all switches........

#7 3 years ago

Check the credit button. It's supposed to insulate from the switch contacts by a piece of paper and or a plastic spacer. If either is missing the switch will be shorted to ground.

#8 3 years ago

I've already disconnected the door plug but problem still exists

4 weeks later
#9 3 years ago

I am returning with my problem still existing. I borrowed an altek mpu and when i put it on, no problem exist. So i am pretty sure that i have a problematic mpu. I changed the u8 5101 ram and its holder and u9, u10 6820 pias and their holders too, but still nothing again. Any ideas?

#10 3 years ago

If you have narrowed down to the mpu I instinctively think battery acid damage. How about a closeup photo of the battery area of the board and the connectors, front and back. Have you reflowed he connectors? Games behaving like the PIA chip is bad or the pins are shorted.

2 months later
#11 2 years ago

Finally I figured it out. It was a bad diode and a resistor in the mpu board. I replaced them and everything is fine now.

#12 2 years ago

Thanks for posting the solution.

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