How many EM's use five volts?

Perhaps, but that would just turn on the power to the rest of the game like the left flipper button. The coin and replay switches start a new game in addition to waking up the game.

You've got the benefit of 40+ years of hindsight. I don't think the designers at the time were being reckless. The safety measures were likely seen as adequate at the time. Even now in the era of ruthless cost savings I think you'd be surprised at the hazards found in lots of modern electronics.

Sure, and they did in later games.

This is sort of like saying "couldn't they just as well have run DC pops?" or "Run a single Pascal type board instead of 3 with interconnects?"

Somebody has to think it up, then sell it then it needs to go in the design pipeline etc. Hindsight is 20/20.

The vast majority of these things are isolated from anything that would possibly have line voltage anywhere near it. If you ground the coin door, the rails and lockdown bar have no way of getting current to them.

He basically wasted a ton of your time to accomplish nothing.

Back in the 70's, I was staying at a small motel in NJ on the way to the shore. They had 60's-70's pinball machines on location in the swimming pool area on tile flooring. Somebody thought THAT was a good idea?!?? Having just had a swim, I happily went over to one of the machines (dripping wet mind you and knowing no better!) and pushed the red start button on the Gottlieb metal door. Yeah, the one with 110v on the start switch insulated, or maybe not, by a thin piece of fishpaper.

I'm not sure exactly what happened but I eventually became aware I was laying on the floor about 5' from the machine and I didn't feel so great. Thankfully, my circuits came back on-line after a minute or so and I was able to walk away sadder but wiser!

On another occasion many years later after I started working on pins, I fixed up a Gottlieb Merry Go Round for a guy with small kids. I explained to him that there was no on/off switch on the game and he would either have to plug/unplug the 2 prong plug each time he wanted to play or get a power adapter and use that on/off switch.

I explained to him that if his small kids were going to be in proximity to the machine, he should DEFINITELY get the adapter. Apparently he didn't and sure enough, his wife called a week or so later to bitch that their son had gotten a shock when plugging in the game. I guess the warning about little kids plugging in the machine was forgotten. Fortunately, I never heard from them again and no lawyers were required!

Ok, so now we are at ground the coin door and the left flipper button and call it a day?

When grounds became standard.. Pinball mfgs grounded leg receivers, lock bar receiver, coin door, shooter rod housing, cab sides . Parts of head unit including locks where applicable. At least from what I've seen.

Yep, I feel your pain. I live in a 100+ year old house, that even has legacy gas pipes in some walls for gas lighting.

I pulled out all the 2 wire wiring and replaced with Romex

I cut out all the galvanized plumbing too

My insurance went down $400 a year, the moment I told them that all the electrical and plumbing had been updated to modern standards

Are you pulling new wire that has a ground conductor and connecting that to the house ground you've added?

My house has 3 prong plugs but no ground wire. I'll be changing to GFCI.

Serious question: Did your house have knife switches and use the screw in type fuses in the "Breaker" panel? My Grand Parents had a home built in 1904 in Southwest Oklahoma that had that kind of set up.
Yeah, some time I want to get my house repiped also.

The conduits are grounded. There's an addition on the house that was built in 1980 that does have three wires and uses Romex.

Someone had put in an 100A breaker panel back in the 90s, but did not upgrade the wall wiring. I moved that panel to the garage.

The garage had an actual fuse box with 4 circuits.

No knife switches, but there were a number of push button light switches.

Screenshot_2022-09-15-08-13-32-51_3aea4af51f236e4932235fdada7d1643.jpg

Bah, you guys worried about a measly 120vac.

One day I was working In the electronics lab at college, and a student called me over to say he felt a tingle when he touched the focus knob on the oscilloscope at that lab station.

Silly me, I proceeded to deliberately grab the knob and was treated to several kilovolts DC, which convulsed my arm and sent me flying backwards!

Turns out some dumbass had replaced the correct, shrouded knob with one that left some of the shaft exposed, and that shaft was hot with the B+ voltage for the display CRT!

I was lucky. Suppose I had rested my other hand on top of the scope first, I would have probably been killed.

I regret not making a bigger stink about it at the time. I don’t think I realized how close I came to curtains until later.

Anyways, I was kidding, of course you need to respect 120v as well.

Just replaced a light switch c. 1930, part of a knob and tube system. Porcelain body, wiring screws right up front where you can get your fingers on them. In a bathroom with steady use, the switching finally failed after 90 years. What's remarkable is that the mounting threads and cover plate holes are compatible with modern. Doubt the replacement will last as long.

image (resized).jpeg

Crazy story. Reminds me of when I decided I was going to mess with my performance ignition system while my vehicle was running.. tiny bit of exposed wire from the distributor was a big zap. I laid down for a while, contemplating if perhaps I would have a special electricity based super power.. but I digress, I had no special powers.. just a sore arm.

We were shooting a music video, so I brought my Jacobs Ladder which runs at 50,000 volts (it's AC, so you get that great humming sound)

I re-warned the band (they'd seen it before), and the crew that the voltage can jump a foot off the electrodes, if it so chooses

Our drummer decided to put his drumstick through the arc (drumsticks were carbon fiber back in those days) and it exploded knocking him unconscious

My Grandparents house had one knife switch before the fuses and a knife switch for each fuse.

My World Fair machine has a 3 prong plug and a ground braid connected all around. Where exactly could I get zapped on this coin door with this switch?

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If that leaf switch is properly insulated, only at the leaf. If your door is properly grounded, not at all.

Great, thank you. The door is grounded. I ran a braid all around the machine. I did order some new fish paper. All the junk parts I have and I don’t have the right size. It’s worn so I’m going to replace it.

You must also consider the plastic bushings connecting the leafs. That mounting screw can short the leafs to the chassis if not properly isolated.

In your photo there's 120 volts between the orange and brown plastic wires on the Replay Button switch, and between the black and white-green-black wires on the Anti-Cheat switch:
World Fair replay button (resized).jpg
It's also on a bunch of Score Motor and coin chute switches, on the Replay unit, on S, W and R relay coils and switches, etc.

I will check the bushings, thanks.

Edit: There’s definitely an issue there. I seem to have intermittent continuity between the coin door and the brown and blue wires. It’s either the bushings or the fish paper.

So I have 120 volts between the orange and brown. But I’m not reading anything between the black and white-green-black. Not sure why.

Edit: It’s probably because of how I wired the on/off switch.

A lot of people in this thread think a GFCI can do more than it is designed to.

If you take two paperclips, stick one into the Hot and one into the Neutral of a GFCI, it won't trip as it's electrocuting you - because it is zapping you in a totally balanced way

Common example of this is the extension cord to your grill.

If the GFCI trips with just the extension cord, then the female end has probably gotten wet. Put it in the sun to dry it out.

I’ve told my wife that we must build a larger gameroom— so that the games can be at least six feet apart for safety. Shhhhh!

Not to hijack the topic, but I just replaced my two prong wire with a three prong, and ran a ground wire to the metal parts. While testing for continuity I happened to notice that the side bars showed around a 19v reading, these i'm not easily able to ground as this is a pitch and bat without a lockbar.

I then disconnected the ground just to see what would happen and I was getting a voltage reading on basically ever metal part. I took out my noncontact voltage tester and it beeps near any of the external metal parts (it doesn't beep to the grounded parts when connected to ground)

This is probably a dumb question, but is it normal that there is a voltage reading on everything metal, even things that don't obvious connect together? Unfortunatly I didn't test with the non contact tester before pulling the two prong plug out.

It's just wire, some grounds lugs, and maybe a 3 wire replacement electrical cord if you bought that version.

Don't mean to sound harsh, but that's what a local hardware store is for.

No.

Yeah I thought so, i'm just really confused because parts that don't even appear to be near power such as the backbox metal door guide show voltage when I have it plugged in. I'll look back at it again tomorrow see if I can figure anything else out.

So are the parts you grounded measuring zero volts? To check, unplug the pin, place the multimeter in the 'ohm' mode, and check continuity from the ground pin on the plug to the metal parts you grounded. Should be close to zero ohms. Always good to short the two meter leads together first to make sure they are close to zero ohms (sanity check).

So why can't you ground the side bars (a picture might help)?

You mentioned continuity and 19V in the same sentence above. Continuity would be for ohms, not volts. Not nit-picking, just making making sure you are measuring correctly.

Might not hurt to use an outlet tester too to make sure the outlet is wired correctly. One of these:
pasted_image (resized).png

LOL, since I ran my yap in this thread, sure enough, the last problem I have on the Cross Town restoration is...getting shocked. First time it's ever happened to me.

I'm pretty sure that the voltage is coming to the coin door, that makes sense since it is the only metal part up front that has any current going to it at all. If I open the coin door so it is not touching anything, I can play the game with no issues at all. I checked the fish paper on the start button and on the coin switches and it all appears to be in good condition.

I ran a wire from the green wire which was attached to the transformer frame, and put the other end on one of the screws holding the coin door on. That caused a big spark at the coin door end connection and blew the 115v main fuse.

So anyone got any ideas here?

#cross-town check your schematic to see what has 110v at the coin door. Game unplugged, use your meter to check continuity from wires in that vicinity to the coin door.
If you have a switch stack mounted on that door you might inspect the plastic insulating sleeve where the screw passes through all the leaves (leafs?). It may have cracked and a leaf is touching the screw.

Pictures might help if you can't locate anything amiss.

I'll take a look. The start button/slam switch is attached to the front door.

Not surprising that when you grounded the door, it blew the line fuse. Just for yucks and grins, reverse the line cord (unless it's three prong), and try it again.
Or, swap the two leads where one goes to the fuse, and the other to the transformer, and see if you still are hot on the door.

Turns out the positive and negative were swapped I noticed the wire color was opposite of what's in the schematics for the wire on the fuse, i'm 99% sure that's the way the old plug was, what surprised me was the machine still worked. Everything is good now ground successful! Thanks, had a busy month and was just able to look at it again.

That's definitely a dead short if you grounded the door and saw sparks/blew the fuse. Try to locate where the spark was, that might be the culprit. And check the plug is wired correctly as jrpinball mentioned.

Maybe someone incorrectly replaced the plug? Or the cord?

Yeah maybe, I tried following the ribbed end of the brown 2 prong that was attached so I knew what the neutral was, so that's why i'm pretty sure it was wrong when I recieved the machine. Oh well, glad it's good now.

Am I reading this right? Looks like only 25v to coin door . 1971 Gtb Drop A Card

5A114D08-148B-477C-BBE8-61FD319E2255 (resized).jpeg

Yes. As EM game designs evolved more and more of the 120V circuitry was moved to the 25V side of the transformer. Eventually only the switch, fuse and outlet remained as in '77 Golden Arrow:
Golden Arrow 120v (resized).jpg
Notice the grounded plug, transformer and switch cover too.

My coin door issue was the wireform for the coin switch was under the fish paper, not on it. Thus line voltage got to the door.

Only found that after looking about 20 times

Is running ground to the hinge where it is screwed onto the cabinet ok, or must it be screwed into the door itself?

That was going to be my next question!

What is a ground plane?

Stock Car Gottlieb 1970. It's at the top of the post