Build Your Own Arcade Controls Forum
Main => Main Forum => Topic started by: LePic on July 21, 2005, 03:18:15 pm
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I have an old generic Jamma cab and I want to install a PC with MAME using JPAC and ArcadeVGA with original arcade monitor. I read a lot of the posts but I can
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Wow... I forgot an important part... See what else is connected to connector P2.
My questions are:
what to remove?
Will the marquee still work? Speaker? coin lights?
Thank you
LePic
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I'm not the expert, but I will tell you what I did with my recent Jamma pickup.
(with power disconnected to the whole cab, of course)
From the power supply, remove all DC voltages +5V, -5V, 12V going towards your jamma harness.
This should be enough. And it appears that the harness would be the only thing affected. Your marquee will still get its AC. I'm not sure about your coin doors, I dont see them in your pic.
As far as the 'details' you want so you can learn, its pretty simple.
1. The jamma board needs DC voltages to operate. Since houses are obviously equipped with AC, you need the power supply to simply create +/- 5V, and 12V from the AC (just like a computer power supply).
2. Your marquee runs from AC, so it is just split off the power cord from you house AC supply.
3. The monitor needs to be isloated from the incoming AC, so it takes your house AC through a isolation transformer. Attaching the monitor to the secondary windings of a transformer seperates (isolates) its power from any noise that may be produced my other potentials on the same line.
4. Your new J-PAC will derive its voltage from the PC it's plugged into. This is why we don't need the DC coming from the power supply in the cab.
5. You could remove the power supply from your cab completely, but would require a little AC line coupling (not too hard), but keeping it in there for a short temr should not hurt anything.
I hope this helps. Let me know if you have any other electronics questions. (I know I got that degree for something :) ).
-Stobe
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It's not vitally necessary to disconnect anything at all, but I always advise people using a J-PAC to disable the game board power supply because this means if the J-PAC is plugged into the JAMMA connector backwards, it won't be damaged.
Disconnecting all the low-voltage wires from the power supply to the JAMMA connector is not really the neatest way. It's far better to disconnect the AC feed to the low-voltage power supply. In your case, disconnecting the AC wires from the EMI filter to the supply would be easiest.
One other advantage to doing this: some older types of switched-mode supplies (ie the low-voltage supply) don't like being run with no load (ie no game board) connected and can make strange noises, waste power or even burn out, so disabling it is a good idea as it's no longer being used.
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If he removes the PS altogether, where does he attach the grounds coming from the harness? To frame ground? Do the DC grounds need to isolated from the AC ground as the power supply has it setup currently?
If you do have other stuff that needs DC voltage (lights for buttons, TB, etc) you could use the existing PS, or connect into your PC's PS.
-Stobe
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I assume the Jpac would ground through the PS/2 or USB cable.