Ground issue - where to start

jhupka

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So I was playing pinball last night, and I noticed that I was getting shocked due to an interesting situation. A bit of back story:

I have been restoring a Flash, and I recently replaced the power cord with a brand new one because the old one was horribly spliced and was also missing the ground prong. So now the Flash and its metal side rails are nice and grounded properly.

I have the Flash sitting next to my working Lost World. But, my Lost World needs a new power cable, too, because it is missing its ground plug. I was playing last night and noticed that if I am touching the metal on Flash and the metal on Lost World when my Lost World is turned on, there's some sort of current leak because I get a mild shock - like touching a 9V to your tongue, nothing too bad. It doesn't matter if the either pinball is on or off - basically something is now finding a path to ground when you connect the circuit from Lost World to Flash to Flash's ground plug.

Now I'm not so sure I should replace the cord on Lost World if I have something grounded that shouldn't be - I don't want to make things worse or blow a bunch of fuses unless I know where this is coming from.

Are there common places this sort of issue could occur? For example, the shock was so mild I'm guessing it is fairly low voltage/low current - so perhaps the GI or a flipper coil circuit is hooked up wrong. Any thoughts on where I should start?
 
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Were you playing with your shoes off on concrete? That may do it too..:D
 
It was carpeted floor. I'll go ahead and replace the Lost World plug then. I just wasn't sure if something might be hooked up inside the pinball wrong or if I had a case where the neutral in the Lost World happened to be a bit above earth ground, and it was pulling things to ground when going through the Flash.

Thanks Ken & Zen :)
 
This is what is going on:

You either have one of your pinballs wired backwards and or your wall socket is wired backwards.

This week I had the exact same thing happen. On mine each machine was plugged into a separate wall outlet. It turns out one of my wall outlets was wired backwards.
 
Get an outlet checker. Then check the wall outlet, and service outlet in your game.

Then you'll know if the hot, common, and ground are wired right and working.

LTG :)
 
Just a follow-up with the solution...

I ended up checking my wall outlet, and that was wired fine. Also, I knew I had the Flash wired fine since the hot wire was going through the fuse. I ended up rewiring the power cord for the Lost World so it now had a ground (pin was cut off old cord). Once I did this all issues went away and you don't get shocked any more when touching both machines.
 
Digging into a '58 Carnival Queen bingo this weekend.. I had to replace the original, brittle cord, with a 2 prong plug. Was going to put a grounded cord on it, but as my dad pointed out, there's no chassis, common ground, frame, nothing...so we put another 2 prong cord on it. I suppose I could have connected the ground wire to 'something' like a transformer, but then that's not connected to anything else!
 
You can run a ground braid to anything metal in the game and ground it all. I would connect anything a person can touch while playing or standing by the game. I have a Carnival Queen that is low on the priority list to work on. I know most of the game is wooden, but when I get to it, I will ground anything I can for safety.

Chuck
 
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