(Topic ID: 227193)

Switch Matrix Issue -- One switch triggers another (Bally 6803)


By Nokoro

7 months ago



Topic Stats

  • 14 posts
  • 6 Pinsiders participating
  • Latest reply 7 months ago by pellew
  • Topic is favorited by 2 Pinsiders

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61805191-F8E8-4A45-A6F1-9B1AAAFB4E5F (resized).png
Switch Matrix annotated (resized).jpg

#1 7 months ago

Hi. I could use some help from switch matrix experts. I've developed a problem on my Bally Special Force. When the Bomb O switch is closed, it triggers that switch and the right bumper switch. I've circled both in the switch matrix diagram below. I've checked the diodes on both switches, and they were good. I replaced them just for good measure, but the problem persists. Am I right it it is likely a short (perhaps a diode) in the column (think row with other games) that contains Bomb B, Bomb O, Bomb M, Bomb B, Capture D.T., and Weapon D.T.?

I just started playing the game again after a bit of a break. I was waiting for a new solenoid expander relay board which I replaced. I did not go anywhere near those switches. However, it is possible that just the process of lifting the playfield knocked something together.

Thanks in advance for the help! (I'm not great with switch matrix issues.)

Switch Matrix annotated (resized).jpg

#2 7 months ago

https://www.pinitech.com/switch_database.php?name=Bally_Special_Force

Love this site for easy to read matrix issues.

You’ve checked both row and columns for both the switches?

61805191-F8E8-4A45-A6F1-9B1AAAFB4E5F (resized).png
#3 7 months ago

Replace the capacitors connected to some of the switches. Some of them were half broken on my special force. They act as a resistor when broken which makes the switch matrix act funny. The capacitors should be about 47 nF.

#4 7 months ago

Thanks for your replies.

I checked all the switches in the row and the column, and there were no obvious shorts. I'm not sure how a capacitor would cause this problem. I've had capacitor issues before, and they seem to behave differently.

Here are two more clues:

1. When I turn on the game or go into switch test mode, the right bumper switch registers as closed. However, when I play a game, the bumper does not constantly fire. It only fires if the bumper switch is hit or the Bomb O switch is hit.

2. If I press the Bomb O switch and hold it, the right bumper fires once, just once. When I release the switch, the right bumper fires once again. So it fires once upon hitting the Bomb O switch and once upon releasing that switch. That seems weird to me.

Do those clues help?

#5 7 months ago

That is the way Bally designed the pop bumpers, one shot only on switch closures.
Replace (or cut for testing) the cap on the pop bumper switch.
It's either the cap or the diode on the pop bumper.
All switches should be open in a test.

My Tech Chart may come in handy.
http://www.pinballrebel.com/pinball/cards/Tech_Charts/Bally_Special_Force_Tech_Chart.pdf
Or checkout the Pinwiki.com http://www.pinwiki.com/wiki/index.php?title=Special_Force

Peter

#6 7 months ago
Quoted from Inkochnito:

That is the way Bally designed the pop bumpers, one shot only on switch closures.
Replace (or cut for testing) the cap on the pop bumper switch.
It's either the cap or the diode on the pop bumper.
All switches should be open in a test.
My Tech Chart may come in handy.
http://www.pinballrebel.com/pinball/cards/Tech_Charts/Bally_Special_Force_Tech_Chart.pdf
Or checkout the Pinwiki.com http://www.pinwiki.com/wiki/index.php?title=Special_Force
Peter

Thanks. I replaced the diode, but I can try to replace the cap and see if that works. Why would a faulty cap on the pop bumper lead the to the bumper switch being triggered when I hit Bomb O?

#7 7 months ago

Yes, it could....

#8 7 months ago

Solved! It was the cap on the pop bumper. I wouldn’t of thought to replace it so thanks to those who chimed in. Can someone explain why that cap caused this particular problem, just for educational purposes?

#9 7 months ago

the capacitor went short circuit causing a path around the switch

#10 7 months ago
Quoted from barakandl:

the capacitor went short circuit causing a path around the switch

Why did it only manifest itself when Bomb O was pressed and not any of the other switches?

#11 7 months ago
Quoted from Nokoro:

Why did it only manifest itself when Bomb O was pressed and not any of the other switches?

Because pinball machines have gremlins in them and are just plain wacky!

Had a similar issue on Paragon, where two pop bumpers triggered each other, but left the third one alone.

#12 7 months ago
Quoted from Goonie:

Because pinball machines have gremlins in them and are just plain wacky!
Had a similar issue on Paragon, where two pop bumpers triggered each other, but left the third one alone.

I figured it was gremlins.

I always try to approach these things logically and feel like I'm missing something when I can't figure it out. But, perhaps the circuitry is just far more complicated than my little head can deal with.

#13 7 months ago
Quoted from Nokoro:

I figured it was gremlins.
I always try to approach these things logically and feel like I'm missing something when I can't figure it out. But, perhaps the circuitry is just far more complicated than my little head can deal with.

Yeah, I long ago accepted that. I'm pretty good at figuring out the what, but the why still gets me to this day. I'm guessing it has something to do with the location of the failed part in the sequence of the matrix, but hopefully someone far more educated can chine in.

#14 7 months ago

Yes, it has to do with the order of the switches in the matrix and the fact that the capacitor has turned into a resistor/capacitor (my guess is due to ESD, long story short). If using a oscilloscope and probing the matrix it is possible to understand this. But it sure looks like gremlins until one fully understand the behaviour.

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