Jamma

Arcade cabinet hardware and accessories
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erzane
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Jamma

Post by erzane »

Why jamma loom needs two +12V / two -5V / four +5V? I heard about a question of balance, that's why it should be both numbers of voltage on each side of the loom, but is that true?

I'm now modifying my wiring and I need a +12v for my amp., maybe can I take one off from the jamma loom and give it to my amp? Or should I add a third one from my PSU?
I don't have much entries in my PSU and since I already have two +12v coming out from that place, I don't want to add a third one, it will be more practice to take off the second one from my jamma loom if possible.

And what about the -5V and +5V?

p.s. my cab will be only 1P (maybe this detail can count).
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Flinnster
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Re: Jamma

Post by Flinnster »

Usually it is only needed to have 2x 5V & 2x GND cables. These are the main 'power' lines that most game PCBs use so it can help to make sure they have more wires or thicker wire that the other connections on your JAMMA loom. It is mainly for older, larger and more power-hungry game PCBs.. and bootlegs.
Quite often you will see pins 1 & A, 2 & B, 3 & C, 4 & D actually soldered together with a single chunky wire coming from them to the switching PSU (2 black colour, 2 red)

-5V and 12V are only used for audio on game boards, so only need a single wire typically. They are not as critical.
(Game boards like Pandora's boxes use 12V instead of 5V as their main power line.. however they are modern hardware so are less picky about power requirements).

If you are adding a 12V audio amp somewhere in your cabinet, take the 12V from the switcher / PSU. It will likely be neater than trying to attach more connections to your
JAMMA edge connector (although in theory, electrically it will make no difference - either will do). You can simply add another fork connector over another under the screw terminal on your switcher / PSU.

1p / 2p / 3p / 4p doesn't make any difference to the Jamma power wiring.
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erzane
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Re: Jamma

Post by erzane »

Since I don't want to ''add another fork connector over another under the screw terminal on my switcher / PSU'', I'd like to use one of the two 12v wires already coming from the PSU to hook to the amp.. Like this, only one 12v wire will be present on the jamma edge connector (pls see the following shema).
I'd like to do the same concerning the GNDs.

p.s. I can't do any bridge on GNDs since I'm using a JST like compartimented edge connector (the same as the one of the egret2) and not a Hirose ''free pin'' connector.
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nem
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Re: Jamma

Post by nem »

https://wiki.arcadeotaku.com/w/PCB_Power_Consumption

As you can see the power draw for +12V is negligible on older jamma games. So yes, you could just use one wire for both +12V inputs on the jamma connector.

However, if your edge connector is one that has crimp on pins, how were you going to split the single wire to both inputs?

Like Flinnster, I would use a third wire and a fork connector and take +12V from the PSU.
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erzane
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Re: Jamma

Post by erzane »

Ok, so I added a third wire for the amp, and let two others for the jamma. Thanks!!
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