What is it connected to?
I can only think someone was trying to smooth out the electric for the lights.
-Mike

25 MDF and sometimes 50 MDF capacitors are used in some 1970's Gottlieb Pins. They will be clearly marked on the schematic.

Helps minimize arcing on stepper unit contacts and contact points in general on the 24-30 volt circuits.

Ok,I clearly see it but what is its actual purpose? Now I am gonna be nosey and check two Gottlieb EM pins I have.
-Mike

Not all capacitors are polarized.

Your picture shows you have a non-polar electrolytic capacitor installed. These can run on AC.

The "crimps" (rings) on *each* end of the capacitor denote it is non-polarized. Large non-polar capacitors like yours are typically used in speaker crossover networks.

In my CCM Hollywood, they have small non polarized electrolytic caps across the lugs of a ton of relay/solenoid coils in the cabinet. Not sure if they're critical components or not in making the game work properly, or if they're used to smooth voltage out to reduce buzzing? I never really found a solution.

I'm with MrBally on this one. I have a Centigrade 37 that I have been working on recently. I think this particular capacitor is used to smooth out the arcing on the Decagon Units (with the the little circuit board) used in the replay circuit (both match and by score). In my research I have seen some of the points burn a hole clear through the board on what was probably a game with a capacitor that had long ago dried up and gone bad. My C37 is fortunately not that bad but I have purchased a 22 microfarad capacitor (because I couldn't find the 25) to replace the original in my game. Anyone with a gottlieb game of this era check the board on your 10's reel and 10,000? reel and if the 25 microfarad cap has never been replaced I am willing to bet that your board will have some evidence of pitting on the traces.

Kramertheman

Rounding out the use cases, I just finished fixing up a Gottlieb 300 and it has a cap for the bonus backbox ball mechanism, to give a bit of delay to solenoid that fires, apparently. Surprised me when I first saw it, thought it might've been a hack...

If this was really the case, they'd be used on every game with a decagon reel, and they certainly are not. I've never seen the pitting or burning on the circuit board of a decagon that you describe. Wear on the board from the wiper point, yes, but never a burn through.

Ken, feeling a little rusty on this probably, and don't want to add too much confusion to this thread as obviously a non polarized AC cap is what needs to be used, but:

I thought 2 straight lines are non-polarized, and one straight/one curved indicated polarized (typically straight side being + if not noted)?

I would have looked at that schematic, looked at how it's being used in circuit, and got the idea but assumed they used the incorrect symbol.

Can you please take a moment to clarify for me? Or show an example maybe?

Thanks as always!

Two straight lines would look just like a NO switch. I imagine they drew it as they did to make it clear it is a capacitor at first glance.

Polarized capacitors are typically denoted in diagrams by a tiny "+" sign next to one terminal.
The symbols incorporating 2 straight lines vs 1 straight/1 curved line typically are used interchangeably and don't signify any difference that I know of.

I know for a fact this is incorrect. A simple google search will show that.

Yes, sometimes the + , or + and - are shown....not always.

Edit: all years I have in electronics have always taught me that the curved line indicates a polarized cap.

Interesting, while it is still wrong symbol and the two straight lines with a capacitive value printed next to it should give it away as a non polarized capacitor, I could see your what you are saying.

Ok, I followed your advice and did a Google search.
I’ll admit I did find a few sites that talked about the curved line for a polarized capacitor. I also found just as many sites that list the symbol for polarized as a + sign. Here are just a couple for example:

http://www.rapidtables.com/electric/Capacitor_Symbols.htm

http://www.learnabout-electronics.org/ac_theory/capacitors01.php

Apparently, the convention is not universally agreed upon.

Hope I didn't come across nasty, certainly didn't mean to be. I see what you are saying about varying symbols (even within UK or US "standards"). Doesn't always make it easy.

I wasn't clear on what Ken was saying. Hopefully he can chime in with even more variances