Pinball accessibility project: new problems!

Hey, all. My project to make a 1972 electromechanical pinball machine save high scores is pretty much done and the core of the idea works very nicely, but it's sprouted new functionality in the meantime, and with it, new problems.

I was wondering how the player would input their initials for a high score. Traditionally, one would use the flippers, but there's two problems with that - first, the flippers run at high-voltage AC (which could be solved using an optocoupler), and second, the flipper switches don't have any voltage at all running through them after the game is over.

So, I built a pair of flipper control boards - the old flipper-button wires are desoldered from the flipper buttons and routed to the output of a solid state relay, and 5v DC is sent (through new wires are attached to the flipper buttons in place of the old ones) to the input of said SSR, and (passing a 10k pull-down resistor) to a digital input pin on the Arduino board.

Additionally, the board has inputs for a second flipper switch, which will run to 3.5mm sockets on the base of the cabinet.

(3.5mm sockets are the standard for accessibility in gaming. The idea is that because everybody's disability is different, everyone will have specific needs - you can't cater to everyone, and it'd be foolish to try. But if you provide inputs for physical control remapping on a simple, cheap, common standard (such as 3.5mm mono audio sockets), then you at least open up the possibility for, say, a one-armed guy to sort himself out with a wee box with two buttons and two wires terminated with headphone jacks, plug it in, and have some one-handed pinball fun. I figure pinball's an excellent candidate for accessibility-switch gaming - hell, there's only two switches, you could even map them to eyeblink detectors. Digression over)

Anyway, the problem that I'm having is that the inside of an electromagnetic pinball machine is tremendously noisy, electrically-speaking, and since replacing the flipper button switch with the SSR, sometimes the flippers twitch a little when the score motor runs, or when the ball kicks out of a hole.

A little flipper twitch isn't really a problem - but I want to run the start button through a similar sort of SSR arrangement, for gameplay-related reasons that are uninteresting and not terribly relevant, and if the start button circuit energizes in the middle of a game, the game just resets. Not good.

I imagine what's happening is that enough RF noise is finding its way into the (fairly long) wires running all throughout this thing that it's proving enough to light up the LED in the SSR, thus flipping the flipper. I've spent a few hours Googling around for techniques to minimize this noise, but this is quite new to me, and I'd appreciate some advice. Would a choke be useful? A filtering capacitor? Some manner of diode arrangement?

Any advice you can give would be sincerely appreciated, and if I can provide any more information, please let me know.

Thanks!

tl;dr:
I'm having problems with solid-state relays activating on their own, because I'm running long wires to their inputs and the wires are going through a pinball machine full of big solenoids and motors.
Could use some advice on methods to mitigate the noise - not sure about whether to use diodes, a choke, wrap tinfoil around everything or what. :slight_smile:

Hi, I've been interested in this thread as I am considering a very similar project for my 1974 Bally Wizard EM pinball machine. Would it be possible to post some of the details of your high-score project?

Many thanks!