Grounding Astro City

[gamezer0]

I recently got a Sega Astro City. The cabinet came with its original 2 pin (=not grounded) Japan/US plug and an internal stepdown (I live in Spain, where there is 230V, whereas the cabinet originally accepts 110V) The cabinet is designed to be grounded via a nut coming from behind, next to the power cord.

Here’s a picture of its original state:

Bottom right you can see the original non-grounded power cord coming into the cabinet and the nut with 3 green ground wires attached to it.

In order to ground it, I decided to replace the power cord by a EU grounded one, and to attach the new cable’s ground to the aforementioned nut.

Here’s a pic of the result:

However, I’ve been trying to double check this is all correct before turning it on, to avoid breaking the PSU or something else (like some user did while trying to do the same! Although I think due to an unrelated reason). I’ve found many related posts here and there, but couldn’t find anything conclusive.

Questions:

• Does this mod make sense?
• In terms of there being an internal stepdown (connected to the two wires coming out of the top of the noise filter of the top of the picture), does this affect the way grounding has to be done in any way?
• There was a ground cable, the one coming from the coin mech, that was detached… not 100% sure where it should go, but based on the size of the cable, I’d say it goes attached the back of the coin box, together with other grounds. Any reason why it could be originally detached? Is it OK I reattach it?
• Anything else I should be aware of/check/test before going ahead?

I have VERY limited electricity knowledge, so any help would be super appreciated.

Thank you!!

 

[skate323k137]

It Honestly sounds like you did it right. The proper way to replace a 2 prong cord is with a 3 prong, attaching ground(earth) to metal. I would have used the same ground point on first glance. I have no idea the implications of an internal step down, however, it seems like you're attaching the mains before it, so offhand I don't think it's an issue. So to answer your question, yes this mod makes sense. I'm assuming you also retained proper polarity of the AC mains.

The loose ground wire... Do you have a multi meter to check continuity? The other end might already be grounded, so I would check first to see if there is continuity between the main ground point and the end of that wire. If there is, it's an existing ground wire that you can attach to any metal piece you want grounded. If there is no continuity, I would probably leave it alone, or try to see if it's got continuity to any metal parts of the cab. If it tracks back to something that should be grounded, then attach it to the main ground point. But if I'm understating your post correctly and there is one end clearly affixed to the coin mech, then I can't see why someone would detach it and it's probably safe to fix in the way you suggested (attaching to the ground screw).

I check grounding on my cabs with a multi meter on continuity or OHM mode. Take one end touching the ground pin of the mains cord, and probe the exposed metal pieces of the cab to see if they are grounded... Control panel especially

Lastly in looking at your pics, did you bypass a power switch? I don't own an astro, just blast and net cities, so I don't know exactly what that is in the lower lefthand corner (power switch or AC out?), but just asking. If it's just AC out then it's not a problem.

 

[Derick2k]

You did the ground correctly.

You could have left the external ac outlet on the cab connected, it would give you 230v without the ground of course. You would most likely never plug anything in there but still could have left it.

Everything else should be fine if the stepdown was wired correctly.

Welcome to the site

 

[gamezer0]

Thanks both for the quick answers!

I'm assuming you also retained proper polarity of the AC mains.

I don't think so... however, given EU plugs can be connected in any way (as opposed to US grounded plugs), this should not matter?

The loose ground wire... Do you have a multi meter to check continuity? The other end might already be grounded, so I would check first to see if there is continuity between the main ground point and the end of that wire. If there is, it's an existing ground wire that you can attach to any metal piece you want grounded. If there is no continuity, I would probably leave it alone, or try to see if it's got continuity to any metal parts of the cab. If it tracks back to something that should be grounded, then attach it to the main ground point. But if I'm understating your post correctly and there is one end clearly affixed to the coin mech, then I can't see why someone would detach it and it's probably safe to fix in the way you suggested (attaching to the ground screw).

I think I didn't explain it too well. Let me rephrase with pics.

I was talking from memory about this one, it wasn't actually attached to the coin mech, but the coin "ramp":

The other side of this cable was freely detached, but I preemptively attached it to the ground screw on the back of the coin box (it's the cable coming from the top on the pic):

Lastly in looking at your pics, did you bypass a power switch? I don't own an astro, just blast and net cities, so I don't know exactly what that is in the lower lefthand corner (power switch or AC out?), but just asking. If it's just AC out then it's not a problem.

You could have left the external ac outlet on the cab connected, it would give you 230v without the ground of course. You would most likely never plug anything in there but still could have left it.

As Derick2k mentioned, this is an AC out so you can (well, this is my assumption xD) chain several cabs together. I detached the cables to prevent any accidents, just in case someone has the temptation to plug in something that requires 110V

BTW, here's a picture showing the stepdown transformer (cube on the right side) in case it adds more info to the matter:

Also, this is the post from AO that is making me so cautious... it sounds like they had a short somewhere and it's not related to the way grounding was done, but posting it just in case...

 

[skate323k137]

Your grounding of the coin ramp is all good IMO, good job!

And I think you're good on polarity then, you would probably know better living there

 

[GeekMan1222]

This all looks kosher and sane to me

 

[Derick2k]

The grounding is fine. open up those splices with the tape on them and make sure they are good. not just the wires twisted together and tape. Either use proper connectors or solder and heatshrink the connection. Make sure the grounding spots are clean of rust etc. and making good contact. You don't need to worry about polarity with these cabs, and also because there is none when using 2 hot wires and ground. make sure that transformer is screwed down and not just bousing around in there. Overall, looks like you did things right.

 

[gamezer0]

The grounding is fine. open up those splices with the tape on them and make sure they are good. not just the wires twisted together and tape. Either use proper connectors or solder and heatshrink the connection. Make sure the grounding spots are clean of rust etc. and making good contact. You don't need to worry about polarity with these cabs, and also because there is none when using 2 hot wires and ground. make sure that transformer is screwed down and not just bousing around in there. Overall, looks like you did things right.

Yeah, that tape is actually mine. There used to be another old tape that was completely off as it lost all its glue over time. There are screw terminals inside, and they looked OK.

Not sure I can screw the transformer easily, but I'll take another look. Either way, I don't plan moving this cab around much (it took a lot of effort to get it to its current location down the stairs), so should be OK as long as I'm careful if I move it around again.

Thanks all for the help!

 

[Derick2k]

Yeah, that tape is actually mine. There used to be another old tape that was completely off as it lost all its glue over time. There are screw terminals inside, and they looked OK.

Not sure I can screw the transformer easily, but I'll take another look. Either way, I don't plan moving this cab around much (it took a lot of effort to get it to its current location down the stairs), so should be OK as long as I'm careful if I move it around again.

Thanks all for the help!

All good then.

If you want to get fancy/screw it down. You can cut a piece of plywood and screw it down using the factory screw locations, just need to get longer screws of the same thread size/count and some washers.

Something like this,

Anywho, good luck with the new cab, have fun

 

[gamezer0]

All good then.

If you want to get fancy/screw it down. You can cut a piece of plywood and screw it down using the factory screw locations, just need to get longer screws of the same thread size/count and some washers.

Something like this,

Anywho, good luck with the new cab, have fun

That’s a good idea. I’ll try to give it a shot

 

[gamezer0]

It works!!

Thanks all for your help. Here’s a couple of pictures of my Astro and my (WIP) arcade/games room.

 

[Derick2k]

Very nice!

 

[gamezer0]

I have one more related question. If I wanted to add an extra plug or power strip to the cab (i.e. to use a Mister or PC with its own power supply), what would be the best place to connect it to?

Presumably I'd take power from the 2 cables coming into or out of the noise filter? Which of the two options would be best? (or maybe none of those?) Then ground would go to the same nut as the others.

Thanks.

 

[Derick2k]

Depending on the voltage of the power supply you will be plugging in, it would be after the noise filter, but before or after the stepdown transformer. Another factor is the noise filter is rated 6amps so also take that into account.

 

[Hackcell]

I have a similar dilemma, I've added a step-down transformer to keep the monitor and PSU with a stable voltage, however, as the voltage prior to the trafo is 120VAC and after it, it goes to 100VAC, I do not know if it's safe to use the 120VAC ground line.

Also, not sure if I have to ground the monitor chassis.

This is a quite crude diagram of my astro current grounding. Any feedback/suggestion is highly appreciated.

Thank you.

 

[gamezer0]

I have a similar dilemma, I've added a step-down transformer to keep the monitor and PSU with a stable voltage, however, as the voltage prior to the trafo is 120VAC and after it, it goes to 100VAC, I do not know if it's safe to use the 120VAC ground line.

Also, not sure if I have to ground the monitor chassis.

This is a quite crude diagram of my astro current grounding. Any feedback/suggestion is highly appreciated.

Thank you.

As far as I know, ground is ground and it's independent from any voltages, so yes, no problem in using the ground from the power entry. If you check the last of the internal pictures of my AC you'll see that only neutral and phase enter and leave my stepdown transformer. The ground is all connected together and comes from my (EU 220V) wall socket.

You don't need to ground the monitor chassis.