Hi my name is Marco I'm new here and believe it or not I already have a question
After couple of months of sitting I finally started up my pinball machine.
As soon as you start the game, as you can see it in the video, even before you shoot the ball, it starts counting score like I have a stuck switch somewhere.
I cleaned every connector on every board upstairs and downstairs with the contact cleaner.
Also I did clean every leaf switch on the playfield.
You can see on video how it starts counting right away.
Upper display flickering it's just a side effect of my camera, actually it's not flickering.
What is flickering it's a SPECIAL light bulb and the one in the left bottom corner.
Does anyone know what this could be, or can I use any self diagnostics on it to figure out what is it?
Thank you so much in advance.

Marco

I ran self diagnostic and in the stuck switch section it gave me number 17.
17. 1, 9 DROP TARGET
I checked them visually and they look okay, nothing is stuck. One more time I give him good clean up with the contact cleaner.
I will get my buddy tomorrow to check capacitors for me.
But what I didn't notice first time, as soon as you start the game first Target on the top right drops right away and it starts counting. I don't know why it drops, it could be mechanical reason?

Thanks,I cleaned expander board relay and connector with the contact cleaner, and that fixed dropping Target.
I couldn't find any 555 light bulb nearby that doesn't work. But nevertheless it fixed that problem.
But I'm still puzzled with closed switch error
17. 1, 9 DROP TARGET .. does this mean 1 and 9 or both targets have stuck switch?

O boy, I think I finally got it it's the first Target on the right top, ball 1 and 9 !?
I checked those visually, they look identical to the rest of the targets.
Hopefully my buddy can stop by tonight so he can check capacitors on that Target.

2021-12-04_15-38-16 (resized).jpg

Thank you everyone for helping me out.
It is capacitor on the second switch. I couldn't wait for a friend of mine to come over so I just cut one leg off from capacitor just to see if capacitor is the problem.
Sure enough it's back to normal now.
I won't play till I replace it so I don't burn off points.

Anyway, one more time thank you guys so much...

I thought they were there to prevent arcing

They used 12V 50pf cap. The closest I can find locally is FILRDL POLPRP 120PF 50V 5LS . Will this one work?

It works...

You are right, my bad, there are stand-up switches...

Original capacitors are 50pf 12V, and I used 120pf 50V

Correct me if I'm wrong but I believe there are 0.05MDF....or 50pf ?
20211204_192334 (resized).jpg

Ok..

My bad... Mixed up NF and MF