Looking for some electrical help dealing with ground (GND) and power (+5v, +12v)

[purbeast0]

I am currently trying to basically use 2 separate PSU's to make one of my arcade games work.

One is built into the cabinet and is a standard arcade PSU and but then I am using another ATX PSU to power one very specific game.

The specific game is a beast and is in it's own metal cage with 4 large PCB's that connect to a smaller motherboard, and then there are 2 other smaller boards that are all hooked together. There is also a 12v fan hooked up to it.

I plan on using the ATX PSU to power the actual game itself. I had to wire up an adapter that went from my arcade cabinet JAMMA adapter to the game itself. However, due to the long power wire run, there is a drop of .5v when it hits the actual game and that causes it to not get enough power. So that is why I plan on using an ATX PSU to power it.


There will be no power at all coming from the JAMMA adapter to the game. All power going to the actual game will be via the ATX PSU.

But the insides of the cabinet that power the switcher that allows me to select this game, as well as turn on the PSU with a relay I have hooked up, are coming from the PSU inside the arcade cabinet.

My question is, do I have to connect the ground wires from the ATX PSU to the ground on the arcade cabinet PSU? I wasn't sure if this was necessary or not because I'm a noob with this stuff and because the game itself is being completely powered from the ATX PSU, however things like the monitor and coin box are being powered by the arcade PSU.

So anyone know if I need to just run a ground from the ATX PSU to the ground in the cabinet PSU? Would there be any downside if I just did it anyways?

I can go into a bit more detail if need be so feel free to ask any questions.

 

[EliteRetard]

If the only issue is some voltage droop, could you not use a DC to DC boost circuit to hold the correct voltage?
Or would there be a problem with the amount of amperage supplied in that situation?

 

[purbeast0]

If the only issue is some voltage droop, could you not use a DC to DC boost circuit to hold the correct voltage?
Or would there be a problem with the amount of amperage supplied in that situation?

I’m not even sure that’s even over my head lol. However I’m trying to do a solution that’s more specific to this game versus more specific to the cable run. Think of this as an external plug that I swap different arcade games to. And everything works fine for the other 4-5 games on this plug.

 

[LikeLinus]

Can't wait for the follow-up house fire thread!

 

[purbeast0]

Can't wait for the follow-up house fire thread!

There will be no fire.

I ended up grounding them together because I am pretty sure since the video feed would cross circuitry it would be safe to ground it.

And everything is working just fine!

 

[snoopy7548]

You don't want to create a ground loop, so you'll want to either have one ground point or isolate the grounds of both power supplies and the respective equipment.

I assume the board you're trying to power with the ATX PSU has some power/signal connection to the other equipment in the machine, which is powered by the arcade PSU; in this case, you want to be careful not to create a ground loop.

I might be concerned over the 0.5V drop in the power lines. How much current is the board pulling, and are the wires (and supply) sized appropriately?

 

[purbeast0]

You don't want to create a ground loop, so you'll want to either have one ground point or isolate the grounds of both power supplies and the respective equipment.

I assume the board you're trying to power with the ATX PSU has some power/signal connection to the other equipment in the machine, which is powered by the arcade PSU; in this case, you want to be careful not to create a ground loop.

I might be concerned over the 0.5V drop in the power lines. How much current is the board pulling, and are the wires (and supply) sized appropriately?

I completely forgot that there is still a VIDEO GROUND wire that was connected on the JAMMA harness coming from the arcade PSU. And that was being wired to the arcade game itself. This is coming from the monitor in the cabinet, which is powered by the arcade PSU.

I am not sure how much current it is pulling as I don't have the equipment to measure that. However the fact it is 4 big PCB's, a motherboard, and 2 daughter boards, as well as having a fan wired up to it by default, makes me assume it gets hot and is drawing a lot of current. Also some guys on the arcade forums basically said if a game has a fan, it draws a lot of power. None of my other games I have have fans on the actual game board itself.

The manual for the game showed this as far as power. I couldn't find anything else other than this.

Logic Power Supply: 200 Watt switching type
Input Power: 120 VAC, 60 Hz, 7 Amps max.

The actual arcade game itself though has no direct power hitting it from the arcade PSU, just the ATX PSU.

Based on the response from the guy who created the switcher told me, I opted to connect the grounds and it seemed to work just fine for the few minutes I tested it out. I am assuming if there was an issue, it would be very apparent from the get go?

I also might just cut off the rest of those ATX connectors that I am not using. I have them zip tied to the side of the game itself but it's bulky and I'll literally never use any of those for anything else. The PSU can't be used on a PC anyways based on what I did to it, and it was only $25 lol.