How to add earth ground.

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    • Report2Marty wrote:

      @rewrite can you send me a link to the guide? Tried searching for it and couldn’t find it.


      rewrite wrote:


      arcadecontrols.com/BBBB/acwiring.html
      The Bob Roberts AC Wiring guide.

      Report2Marty wrote:

      Also, I’ll need to order one that outputs 100V, correct?
      Don't know. Does the chassis you ordered and installed require 100v?
      On the hunt for: Dinoking, Mushiking, Love & Berry, Egret 29, and an SNK SC-25.

      Shameless plug: Rewrite's Recaps - Your monitor and PSU recapping service center
    • Most chassis have a range of input AC voltage they support. So likely 100 vs 120 is moot. However, look up the manual for your exact chassis before purchasing and hooking anything up.

      Some isolation transformers will have multiple pins that can output different voltages. It depends on how the windings are done and the design for where the taps are. So some isolation transformers can output 100 and 120 depending on where you hook up to it.

      All transformers will have some sort of VA rating, this has to do with how much overall power the transformer can safely deliver. Usually physically larger ones have the higher VA ratings.

      I am currently using a midway transformer on my monitor test station. I have it set up to connect to the 120V AC isolated output for all monitors I hook up (that allow it). Even monitors that don't require an isolation transformer, it doesn't hurt anything.

      I also have a green earth ground cable that connects all the metal frames of my devices together (transformer, power supply, monitor chassis) and goes to my outlet earth ground. This is not necessary for operation, but is a fault protection. The earth ground cable will be tied to your AC neutral line in your house, but there should be no connectivity across the isolation transformer.
      Woodies: Xevious, Pac-Man, Centipede, Dig Dug, Donkey Kong, Joust Cocktail, Space Invaders, Initial D3 Single, Mortal Kombat II, Zaxxon, Galaga, T2, Space Shuttle Pinball
      Candies: 2x Aero City, New Astro City, 2x Blast City, Net City
      Other: Wacky Gator, Shoot the Moon, Movie Stop, Sega SpongeBob, SpongeBob Jellyfishing, AC6007
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    • rewrite wrote:

      KaPH33n wrote:

      In that diagram it shows the monitor connected to Earth Ground via green wire with ring terminal.
      It looked to me like that was connected to the iso transformer, but I see now that it is just INCREDIBLY CLOSE TO the iso transformer.
      Yeah on the link in the last paragraph it states the hot chassis can be safely grounded to earth with the use of an isolation transformer (as the neutral is no longer referenced to earth).
    • OH! Actually, I have a question. The outlet I use in my garage is too small to fit the multimeter probes in, so I measured output and earth ground through a basic 6-way power strip. Will this give me a correct reading, or does the power strip have something internal that will give me a false reading.

      also, I’ve read that when testing for earth ground from an outlet you should get the same reading 120V (in this case) when red probe is in the live and the black probe is in the earth ground. Have I been given false information?

      THANKS, Again!!
    • Report2Marty wrote:

      OH! Actually, I have a question. The outlet I use in my garage is too small to fit the multimeter probes in, so I measured output and earth ground through a basic 6-way power strip. Will this give me a correct reading, or does the power strip have something internal that will give me a false reading.

      also, I’ve read that when testing for earth ground from an outlet you should get the same reading 120V (in this case) when red probe is in the live and the black probe is in the earth ground. Have I been given false information?

      THANKS, Again!!
      power strip is fine, it won't change anything.

      yeah you should be able to test 120v with live and ground. neutral and ground should be tied together inside your main panel of your electrical system. however you won't be able to do that with the isolated 120v.
      Woodies: Xevious, Pac-Man, Centipede, Dig Dug, Donkey Kong, Joust Cocktail, Space Invaders, Initial D3 Single, Mortal Kombat II, Zaxxon, Galaga, T2, Space Shuttle Pinball
      Candies: 2x Aero City, New Astro City, 2x Blast City, Net City
      Other: Wacky Gator, Shoot the Moon, Movie Stop, Sega SpongeBob, SpongeBob Jellyfishing, AC6007
      VAPS
    • Hi Everyone!

      I just received the iso transformer, and in all honesty, I’m a tad overwhelmed here .

      I’ve posted some pictures of the current setup along with a picture of the isolation transformer. I know it’s a lot to ask, but if someone could be so kind as to point me in the right direction. Sadly, I have no idea where to start.

      Thank you so much for your help. Sorry to be a bit of a bother.
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    • Ok, I’m beginning to make a little headway following the Bob Roberts guide. Quick question though... Referring to the picture below, B Roberts guide says I should attach the earth ground from the ac cord to the middle prong of the ac filter. Does this look correct, and should I do this instead of leaving the earth ground attached to the designated ground screw on the floor of the cab?

      Sorry for the noob questions....

      Thank you for you help!
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    • it looks like you got a 120vac input iso with 100vac output. I don't know what your manual said, but I think you need a 1:1 isolation transformer that does 120 input and output.

      Once you verify you have the right input and output voltages just hook up the iso to the plug that's already there for monitors. plug -> iso input -> iso output -> monitor input. (do some voltage checks along the way before plugging into the chassis).

      the switching power supply is already hooked up to ac. it looks like it has an output too which could probably be used to feed the iso as well, but no reason to do that. I would try to use the existing stock wiring as much as possible.

      If you want to be simplistic but still safe about it get some wire nuts. get the right size for the gauge of wires you're using. the best way is to solder all of these connections together and cover with heat shrink wrap. if it were my cab, i'd be soldering down everything and running wires cleanly.
      Woodies: Xevious, Pac-Man, Centipede, Dig Dug, Donkey Kong, Joust Cocktail, Space Invaders, Initial D3 Single, Mortal Kombat II, Zaxxon, Galaga, T2, Space Shuttle Pinball
      Candies: 2x Aero City, New Astro City, 2x Blast City, Net City
      Other: Wacky Gator, Shoot the Moon, Movie Stop, Sega SpongeBob, SpongeBob Jellyfishing, AC6007
      VAPS
    • Report2Marty wrote:

      Ok, I’m beginning to make a little headway following the Bob Roberts guide. Quick question though... Referring to the picture below, B Roberts guide says I should attach the earth ground from the ac cord to the middle prong of the ac filter. Does this look correct, and should I do this instead of leaving the earth ground attached to the designated ground screw on the floor of the cab?

      Sorry for the noob questions....

      Thank you for you help!
      leave it where it is. the line filter in that cab is sitting on a nonconductive piece of wood. it kind of depends on a few factors but metal candy cabs should be earth grounded to their chassis. sega astro city cabs have the ground symbol next to a threaded post on the filter board plate.
      Woodies: Xevious, Pac-Man, Centipede, Dig Dug, Donkey Kong, Joust Cocktail, Space Invaders, Initial D3 Single, Mortal Kombat II, Zaxxon, Galaga, T2, Space Shuttle Pinball
      Candies: 2x Aero City, New Astro City, 2x Blast City, Net City
      Other: Wacky Gator, Shoot the Moon, Movie Stop, Sega SpongeBob, SpongeBob Jellyfishing, AC6007
      VAPS
    • Thanks @KaPH33n!

      here are some pics of what I’m going to do, I think. I decided to remove the outlet so I can wire straight to the iso and have a good place to mount it (bad idea?). Also, you’re right, I bought the wrong damn iso.... thought I ordered the 1:1, but nope... oh well, I’ll keep it if I ever convert back to the original monitor and chassis down the road. The 1:1 has been ordered as of this morning.

      Quick question, can I make a loop by attaching the earth ground wire from the power cord to the metal frame of the iso transformer? Doing that will connect it to the ground screw next to the filter, correct? So, if that’s true, will the monitor chassis need to be grounded in some other way, perhaps a wire running from ground on the chassis pcb to the metal frame of the iso? Sorry, just trying to understand how to make an earth ground loop. I’m sick of this damn cab shocking me when I go to turn it on....
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    • Report2Marty wrote:

      Thanks @KaPH33n!

      I decided to remove the outlet so I can wire straight to the iso and have a good place to mount it (bad idea?). Also, you’re right, I bought the wrong damn iso.... thought I ordered the 1:1, but nope... oh well, I’ll keep it if I ever convert back to the original monitor and chassis down the road. The 1:1 has been ordered as of this morning.

      Quick question, can I make a loop by attaching the earth ground wire from the power cord to the metal frame of the iso transformer?
      I would leave the outlet as it's a part of the stock cab. I like to do non-destructive mods when possible. It's very easy to get a bare ends AC cable from amazon for a few dollars. just connect it to your iso input and plug it in. then it can be removed easily if someone gets an itching to revert back to the original monitor. Since you already did it though... just put the original parts in a bag or box and keep them inside with the cab.

      Grounding can be a chain or a loop or both, doesn't really matter as long as it's all connected and has a path to the outlet's ground.

      nem wrote:

      Your 120VAC to 100VAC transformer would have been fine. The chassis is expecting 110V. 9% difference would be in tolerance. What voltage are you getting out of your outlet in your home?
      I agree that it would have most likely worked, but he is trying to get this set up and understand how/why it works this way. I want him to know what parts he's picking and why... It's better to set things up the "right way" and not just settle for "what works" imo. It doesn't hurt to have extra isos around either.

      You're getting close.
      Woodies: Xevious, Pac-Man, Centipede, Dig Dug, Donkey Kong, Joust Cocktail, Space Invaders, Initial D3 Single, Mortal Kombat II, Zaxxon, Galaga, T2, Space Shuttle Pinball
      Candies: 2x Aero City, New Astro City, 2x Blast City, Net City
      Other: Wacky Gator, Shoot the Moon, Movie Stop, Sega SpongeBob, SpongeBob Jellyfishing, AC6007
      VAPS
    • thanks @KaPH33n! Is it possible you can help me plot out a comprehensible earth ground loop that will prevent me from getting shocked when I go to turn the candy cab on?

      Also, is it a concern that the cab is asking for 100v and my iso and chassis will need 120V? Will this cause any potential interference? I was getting a lot of waves in my picture before. What could that have been from?

      Lastly, (sorry for all the questions.. just trying to understand all of this the best I can) the iso wires in and out have no markings or indication if one is common or one is live.... does this matter?


      Thank you so much for all your help!