The title is Strikes & Spares, and the row of switches is row I5, which includes a bumper and a few other switches. When the game is powered up and into game play, if any of these switches except for the bumper is actuated, everything is fine. However, when the bumper is actuated, not only does the bumper not work, but all the other switches in the row no longer work, and won't work again until the game is powered down & up again.

So I figure that there is something wrong with the bumper. The diode checks out, and as I don't have a multimeter capable of measuring the .047 μF capacitor (one is on the way!), I just presumed that was the problem, so I put another capacitor in parallel to the one then installed, and the problem disappeared ... for a little while; now I have the same problem, as I am currently down to only 1 good .047 μF capacitor (more are on the way!), I don't want to sacrifice it until I have some explanation.

#2 5 years ago

PIP

Quench

Pinside member

8y 114K 8,017

These switch capacitors typically start to short circuit when they fail. So if you suspect any are faulty, you need to disconnect them from the circuit. Best to clip one of the capacitor leads close to the lug it's soldered to and then bend the capacitor lead away so it doesn't touch. If the problem doesn't resolve, you can then resolder the capacitor.
The switch will still work without the capacitor connected, however on very fast hits the CPU may not have enough time to sense it.

What is switch test mode telling you when the fault occurs?

#3 5 years ago

???

swampwiz

Pinside member

Bogalusa, LA

12y 32,300 763

After getting into the state of no actuation for that row, the test shows no bad switches.

I guess you are saying that I should check every capacitor on that row?

#4 5 years ago

PIP

Quench

Pinside member

8y 114K 8,017

If switch test mode reports no closed switches then you might not be looking at a capacitor issue, rather a connector issue at the MPU board with the "I5" return signal. Check pin terminal 13 of connector J2 at the MPU board.
Shorted capacitors will start to show the respective switch as being closed in switch test mode.

#5 5 years ago

???

swampwiz

Pinside member

Bogalusa, LA

12y 32,300 763

Quoted from Quench:
If switch test mode reports no closed switches then you might not be looking at a capacitor issue, rather a connector issue at the MPU board with the "I5" return signal. Check pin terminal 13 of connector J2 at the MPU board.
Shorted capacitors will start to show the respective switch as being closed in switch test mode.

So how could there be a connector issue if the signal works once, but then not later? Or are you saying that there is just barely enough corrosion resistance to allow it work sometimes, but not other times? That's an easy check to do, so I will do it.

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