JAMMA Cab preparation for JPAC

[aeroflott]

Hi,
I'm about to convert a working JAMMA cab to a MAME system, using a JPAC. Ultimarc's site says the following:

It is usually preferable to remove any low-voltage game board power supply which is fitted inside a JAMMA cabinet, leaving only the monitor powered from AC mains (via the cabinet isolating transformer if fitted). With no game logic board to provide a load, most cabinet power supplies would not work anyway. Also keeping 12 volts away from the J-PAC will eliminate the risk of damage in the event that the JAMMA connector is ever plugged in backwards. Another alternative is to unplug the AC feed to the game board power supply. Ensure that doing this does not also disconnect the ground!

IMPORTANT: If a cabinet power supply IS still operating, make doubly sure the JAMMA connector is plugged on the correct way round otherwise the J-PAC will be damaged as 12 volts would be applied to the inputs.

In plain English what does this mean? I was hoping not to have to hack the cab at all, and was under the impression that all I had to do was plug the JPAC into the JAMMA interface and away I go? Is it absolutely necessary to disconnect power to the JAMMA adaptor, or just prefereable?

Thanks

T

[paigeoliver]

You just have to remove the power supply.

It is a metal box. Unhook everything from it (taping up the wires with electrical tape) and take it out.

This isn't 'hacking', it is brainless and easy and anyone can do it.

If you can't manage to do that then this hobby might be too much for you.

You HAVE to do this, otherwise you have a power supply with no load operating in your cabinet which will burn up and smell bad and will continue to burn up and smell bad until you TAKE IT OUT.

[aeroflott]

"Hacking" was perhaps a heavy choice of word on my part, but I appreciate the sentiments of your reply.
I've built more than one MAME cab in my time, but never from a JAMMA setup before (i've always used IPACs up until now).

So where does this leave power to the monitor? Does removing the power supply affect the monitor?

Can I assume that in most modern JAMMA cabs, the power supply to the monitor is seperate from the Power Supply that feeds the rest of the machine? I'm comfortable with most electrical things, but messing around with power and monitors makes me nervous at the best of times. (I ask because I've not seen the cab yet - it's an "Astro City" type cab if that helps).

Thanks

[paigeoliver]

The monitor doesn't have a power supply. It probably has an isolation transformer, but not a power supply.

The power supply only supplies power to the boards (and sometimes the coin counters). Just unhook all the wires from it, tape them up and you will be fine.

I usually take that extra step and completely remove all the unused wiring, but that is your call.

[aeroflott]

Much appreciated - thanks for clearing that up.

T

[paigeoliver]

And if the supply came out of a working game then you can get $10 for it on ebay.

[MartyNg]

I know this thread is pretty old...but I have questions that are directly related.

I've been running a JPAC in an JAMMA cabinet for a few months now without any problems. I did not remove a power supply or anything. I just took the JAMMA game board out. Is this dangerous? Am I understanding this correctly....the power supply is not needed at all? The arcade monitor will still power on/off with the power switch if the power supply is removed? It would be nice to remove the power supply as it takes up a bit of room I could use for my PC stuff. Also, is there a FAQ or a good topic anywhere discussing how isolation transformers work? I think I have one of those, and I should probably learn how it functions. Thanks!

[RayB]

No, you don't need the power supply, since the JPAC takes its power from the PC.  The reason they recommend to remove it, or at least cut power to it (the arcade power supply) is that
1. If you plug the JPAC in backwards by accident, it will get fried.
2. Some arcade power supplies slowly burn up when they have no load (other's automatically shut off)

all your other questions: www.therealbobroberts.net

[CheffoJeffo]

Mandatory BobRoberts link:

http://www.therealbobroberts.net/buildit.html

Cheers

[MartyNg]

Cool. Thanks for the links guys! I skimmed an article, and it looked like it had some good stuff in there. I can't wait to remove my power supply! It takes up so much room! I don't care if I lose power to the coin slots. I just need to make sure my marquee still lights up!

[RayB]

Cool. Thanks for the links guys! I skimmed an article, and it looked like it had some good stuff in there. I can't wait to remove my power supply! It takes up so much room! I don't care if I lose power to the coin slots. I just need to make sure my marquee still lights up!

You could rewire the coin slot bulbs to take power from your PC power supply.

[FrizzleFried]

Are those coin slot bulbs 12v or 5v?

[diverdown]

Are those coin slot bulbs 12v or 5v?

you need to know this so you dont send 12v to your JPAC.....this will fry it.


And for others...  If you dont want to make this a permanent removal..... I just removed the input power lead to the Power supply from the isolation transformer and left all the other wiring as is... That way if i need to test a pcb its a quick swap and 2 wires.