Leeds
I had a severe hum on my Jokerz and it was caused by a failed bridge rectifier. Same thing as the filter caps really but more drastic.
(Topic ID: 198010)
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Jokerz!
Williams, 1988
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Quoted from Oldschool77:Well recapped the board, and it helped a tad. I'd say the hum is about 70% as loud as prior to recap. The AC ripple is "in spec" now, but it's still insanely loud. Luckily i have my fully functioning Taxi right next to it with the same power board. And as i mentioned before, when i put the Taxi power board in the Jokerz the Jokerz works just fine. So i feel like i can rule out anything other than the power board.
So at this point, unless someone has any suggestions of where else to check on the board, I'm going to power up both games up, without the sound boards connected, and compare voltages all over both boards until i can isolate another component that isn't consistent with the Taxi's power board.
Also...how do i know if the rectifier is bad? Would it show up on the test points?
I'd change the bridge rectifier on the power board. Cheap and easy to do.
Quoted from Oldschool77:Replaced the rectifier and all is good now, thanks for all the help!!!
On a side note.....I'm only at around 11.4VDC.....is that within acceptable limits, or should i worry that something else may be on it's way out too? Everything plays and sounds normal (as normal as it can be for Jokerz lol)
Leave it be mate. It will be fine.
Told ya about the rectifier 
Don't know what it is about Jokerz (probably the one of a kind sound board) but it is very sensitive to ac ripple.
Great that you have fixed it. Simple, but fun game.
Quoted from Oldschool77:Thanks! Will do! And i agree. When i put the power board in my Taxi, there was a little bit of hum, but barely noticeable.
Yeah Jokerz is fun, my kids love raising the drawbridge and getting the super easy multi ball! If it was my only game I'd probably get bored, but the family likes it, and it's a really really (Python!!!) nice looking game so that's worth it to me!
Jokerz was the first game I bought so it has a special place in my heart. I actually know where it is and I could buy it back if I wished but I am all modern Sterns these days.
I LOVE the music on Jokerz when you get a high score.
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Leesburg, VA
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