I don’t think you would ever notice the shock of 1 volt.

Has to be something else going on. Did you check on the ground wires in the cabinet.

Measure from the lock bar to the ground braid - it should be zero.

Since you felt a shock from the lock bar, measure from the lock bar to ground. Ground can be a leg on another machine or any of several methods.

Take off the lock bar, test the lock bar receiver.

Checking the ground braid is good, you want that functioning to dissipate any voltage that gets where it shouldn’t but that’s not the cause of the stray voltage. Further investigation will be needed to find the source.

Your meter reads 36 mv. That's a tiny stray voltage that could be caused by a tiny resistance in your test leads.

Put the meter down until you completely inspect the ground braid. Excellent chance it's broken in at least one place. You should have continuity from the metal ground plane in the backbox all the way to the lockbar. Ground braid in lower cab may be disconnected at the head, or it may have breaks near the playfield hinges. Put playfield all the way up to inspect lower cab in front, then slide it out the rails to inspect the back of the lower cab and where the braid goes up to the head.

Easy excercise. Just look for breaks or disconnected sections on the ground braid. Also, don't forget to add the ground braid back to the power box when you screw that back in.

Adding to your comment: You measured DC, AC is the real important measurement (which you did).

Unplug the pin from the wall, measure continuity between the ground plug of the pin and the lockdown bar.. should be close to zero.

Looks like you have a bad ground somewhere.

Unplug the machine and ohm out the plug to the service outlet. It is an easy way to check if a cord was mis-wired. I've found a lot of cords where the hot and neutral wires are swapped.

Replace that cord cap!

Agree, replace the cord and plug. You can wire in a new plug, but better and cheap to go with new cord with plug. 14 gauge is best if you can get it, but 16 gauge will work as long as it's not longer than factory.

If you're not comfortable soldering in the power box and the rest of the old cord looks good, you can just add a new plug. Watch your polarity either way.

Excellent!

Edit: Adding to other comments:

Sounds like you need to go to Home Depot, local hardware store, etc., and get to new power cord.

Double check what you think is really intermittent. i.e. Is it really the power cord, ground braid, kludge, etc.?

The longer the new cord...the lower the gauge wire.

If you think your capabilities are up to par, you can maybe can replace the plug. Otherwise replace the cord and wire correctly.

Holler if you need help.

If extension cords are cheaper than the "utility" cords with the stripped end you can just hack off the female side of the extension cord.

not sure why "outdoor" extension cords are cheaper than indoor ones, but the outdoor ones don't normally come in black anyways.

Here's a couple of decent options at HomeDepot (or a local hardware store).

You'll need to make sure you wire up correctly. Please don't guess!

Double check here, lots of smart people here that will help you wire it up correctly.

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I buy the orange plug at my local Home Depot.

Measure after you have replaced the cord cap. Trying to find the source will be very difficult unless you start blowing fuses or “magic smoke” starts escaping.

You need to keep testing. Isolate components. Remove the lock bar. Is there current on the receiver? Rails? Legs?

The voltage can be a clue. If you’re getting 60v AC and nothing on the playfield has AC then the stray voltage isn’t coming from the playfield.

I’d be checking the service outlet and cover. Maybe something touching that shouldn’t be.

Fix the ground issue and go from there. I've been shocked from a bad ground before...it doesn't take much current. Voltage isn't the issue, it's the current that is dangerous. The purpose of ground is safety, if 'ground' isn't ground, then sort of a moot point. It's not serving it's intended purpose.

Make sure you wire it up correctly!

You haven’t found the issue. It’s just being dissipated safely to ground as it should be when there is a malfunction.

As old pin points out, you have not found the source of the problem. Since the voltage is AC, that means it can be from any of the AC lines before AND after the transformer.

A very close visual inspection of any wire with AC on it may be your best bet in trying to find the source.

If visual does not find the cause, The only way I can think of right now of how to isolate is to duplicate the original problem and lift one AC source at a time until it disappears. Not for the faint of heart or someone inexperienced in chasing these things down. Maybe old pin has more experience with chasing these issues down.

I agree with Billc479 . The metal cover and especially where the wires exit, could be compromised insulation there?

If you start at the lockbar, what else that conducts electricity touches it? Does that have current on it? If you disconnect the ground braid does it still have current on it?

Do you have a Kill-A-Watt? Does the pin draw significantly more amperage than other examples of the same pin? It’s not blowing your breaker so odds are it’s not drawing much.

Happy hunting.

The current will take the path of least resistance. If that is the game’s existing ground system then your measurement will probably show nothing. There are multiple things you can try:

Since you’re new at this and dealing with a significant amount of current let me reiterate caution. This voltage can be dangerous. If you or someone else playing the game becomes a better path to ground you could get shocked again.

Consider calling a professional.

Twice, I actually started to type up the very same response as you (not worded as well as yours tho ), but both times I ended up being a little skittish and never posted. As you stated (and I did too in an earlier post), not having a ground itself is a fault, that needed fixed first and foremost. As an electrical engineer (and obliviously not an electrician), I have to remind myself what I understand can be misconstrued by someone else who doesn't have the same background. So I chickened out and played it safe. I even worry when I tell someone to replace a plug, thinking they might accidently swap the hot and neutral.

Short story: While pursuing my degree, I worked as a troubleshooter at a defense contractor. I noticed I would get a shock between some test equipment and an environmental chamber. The problem? A bad ground connection, and an electrician was called in to fixed it. End of story, and I was back to working.

If the O/P wants to really know if this would have been a problem, he would have to unhook ground again and measure the current between the lock down bar and ground. If I'm not mistaken, I think it's in the 60mA range that's fatal. But I agree with your comment - leave it alone, especially if you don't know what you are doing. If I had a concern, first thing I would look at is the EMI filter (as you mentioned) for a leaky cap. Or maybe the filter caps are a value that results in some minor current flow to ground at 60Hz.

Just by nature of how they work - line filters will always have leakage current to ground.
Inside the filter is an array of inductors and capacitors. There are AC 'across-the-line' type capacitors tied from hot to neutral, from hot to ground and from neutral to ground. As long as there is AC power applied to the filter - there will always be leakage current. This includes when the power switch is turned off when the filter is often prior to the power switch. There is still power present within the AC filter in the diagram shown in post #38 hence there will be leakage current even with the switch turned off.

Leakage current is a actually a measure of filter performance. Contrary to common sense, the higher the leakage current, the better filtering. Yes, this seems counter intuitive. But if you think about it, high level analysis says better caps will filter better and conduct higher current during the filtering.
The line-to-ground capacitors provide a path for AC current to flow to the chassis and to ground. As long as the equipment has a good ground, this current will flow into the ground circuit and present no hazard. However, when the ground connection is faulty, the earth connection may be established by the human body. There is a maximum limit to leakage current for obvious safety reasons. US, Canadian and European safety puts the maximum leakage current limit at 3.5mA. Most filters used in pinball/arcade equipment is similar to the Corcom B series such as 5VB1. These have maximum leakage current of 0.4mA (120VAC power) or 0.7mA (240VAC power). Enough to feel it but not to kill or harm you. It takes about 10mA at 120VAC to physically affect your muscles and just over double that to affect your heart.

Sometimes these filters do go bad. Caps will either short out, open or become excessively leaky.
Open caps are not an issue but will result in less filtering.
Shorted caps will take out the entry fuse.
Excessively leaky caps can become a safety hazard.
Only sure way to test a line filter for excessive leakage current is to actually measure it between the filter's ground connection and the AC power cord's ground. Suggested method is to install a 1500 ohm resistor between the filter ground and actual ground. Measure the voltage drop across the resistor. Divide the voltage drop by 1500 to determine leakage current. Don't leave the resistor there - make sure to reground.

I didn't even think of such an easy method of isolating the ground -> an adapter plug.

The Corcom B series filter such as the 5VB1 has a maximum leakage current of 0.4mA.
You are seeing 0.57mA.
Not knowing exactly which filter your machine has inside, this very well could be the normal leakage current within the filter.
What brand and part number is on your filter?

5VK1 -- that one has a maximum leakage current of 0.5mA. Yours is a little high and is showing it's age. Debatable on replacing him but as long as the game is grounded, you should be fine. Some of the leakage current could be sloppy connections, though.

If you were to replace - a TDK makes a decent replacement. Pretty much the same footprint with a bit higher current rating:
https://www.greatplainselectronics.com/proddetail.asp?prod=ZHG2206-H

If it were me - I would just make sure all the solder joints were fine and stick with that one.

Looking at the data sheet, it's spec'd at 0.5mA for each line (1mA total) to ground. I think you are good to go, other than checking the solder joints.
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Big thanks to Ed G-P-E for the detailed explanation. I’d sleep well at night if I were the OP. Seems likely you’ve found the issue.

Yes, or have someone show you. It's really not hard IMO to learn to solder correctly. There is a really good thread here on pinside (I think by @terryb) that covers the basics including links to videos.

Test Pinbot, just for kicks.

https://pinside.com/pinball/forum/topic/terrybs-soldering-guide-part-1