(Topic ID: 251226)

Rebuilt Black Knight power board, now getting mild electric shock

By kevinclark

6 days ago

Topic Stats

  • 5 posts
  • 3 Pinsiders participating
  • Latest reply 5 days ago by kevinclark
  • No one calls this topic a favorite


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#1 6 days ago

Hi folks - thanks to the wealth of information I found here I was able to transport my childhood pinball machine from my parents place today and replaced many of the components on the power board to fix the display issue I’d been seeing before. Digits are looking way way better. But now I’ve got a new symptom - I get I mild electric shock when I touch the latch to open up the back box and when I touch the rails on the cabinet.

The wall plug appears to be missing a ground pin and I’m planning to fix that this week. Does it seem likely that the shock issue will resolve when I do that or is it indicative of a bad board repair? The pin seems to start up fine.

I’m wondering if there had always been a little voltage getting discharged into the pin and the crappy voltage pre-capacitor swap just might have masked it? The other major variable that changed is that the pin is in my garage on a cement floor vs on carpet previously - maybe it’s just not grounding in the same way?

Anyway, very much appreciate your thoughts.

Edit: Worth noting I followed Vid’a bulletproofing guide to replace components on the power board.

#2 6 days ago

Fixing the ground pin should fix your shock. It's best to leave the machine off until then, getting a shock from machines is never good.

It is possible that you fixed the ground on your driver board so it now connects to the ground on your machine. This is good. You can verify that all grounds on the machine are the same (coin door, test points on PCB, pin on power cord).

#3 6 days ago

Replace the plug on the power cord and you should be ok.

#4 6 days ago

Great, thanks guys! I unplugged it as soon as I noticed the shock and it’ll stay that way til it gets proper ground.

#5 5 days ago

Just to follow up - new plug is on and the tingle in my fingers is gone. Thanks!

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