Building a supergun..

[Rengoku]

ok i want to go into this i'll use this thread to ask something sometime (instead of always bothering MKL by pm :P )

i'm using this as main reference
http://chadsarcade.co.uk/oldsite/Supergun/supergunIndex.htm

everything is explained pretty well but i still have some doubts

on my SG i have 3 potentiometers on the video signal (obviously R G B)
are those really needed?'cause i just play mvs pcb or atomiswave without changing anything
and if i have to use them wich one should i use?

 

[zapatistab]

I saved this from an old thread. Hope this helps.

 

[Rengoku]

great stuff thanx

 

[Murray]

To answer your question, you probably don't need the pots if you're just using those two boards. Chances are pretty good that you can just replace them with some resistors and never need to modify it.

I forgot exactly what I used when I did that but I think it was either 110 or 180 ohms. It will depend on what you're using for an encoder / monitor anyway, so it would be good to have a selection available to test with.

 

[Rengoku]

in zapatistab scheme there are some resistor between jamma harness and speakers..
those are for?

 

[Drewmantrivia]

The diagram is mine from a while back that I whipped up for myself to make it more clear for supergun setups. The resistors that are placed in-between the jamma harness is for dropping the amplified sound from the jamma board or neo-geo down to a level that will let you use it with a tv w/o damaging the speakers. You could just wire it up to some old speakers you have directly too just like in a arcade cab. The switch is for when you go from a neo-geo board back to a jamma board that is mono and doesn't have stereo. Just flip it and it give you fake stereo to both speakers.

-drewmantrivia

 

[werejag]

where did the button art come from?

 

[Drewmantrivia]

I just drew it all out in MSpaint. Then cut and copied everything to the guide. I would love to do one for a kick harness setup and those old D&D games but i can't find any really good info that would do that. (Or make senes to me) Oh well...

-drewmantrivia

 

[Rengoku]

i want to go for a scart connector
so which signals (in addition to rgb sync and ground) i have to send to there?i know that the 12V on pin xx (i can't remember it right now) will automatically change tv to AV mode

 

[Rengoku]

The resistors that are placed in-between the jamma harness is for dropping the amplified sound from the jamma board or neo-geo down to a level that will let you use it with a tv w/o damaging the speakers.

but for this you can't just lower the sound potentiometer or sound volume directly to the board?

 

[Drewmantrivia]

You could, I believe, turn the pot way down and hook it up to the tv and get ok sound. But for the cost of 4 reistors and the piece of mind that it won't blow your tv's speakers why not? Resitors = cheap. Blown TV speakers = $$$.

Other than that being in the USA i don't know the pinout to a scart connector. I do know that you will need to get the switching working like you said but it is way past me on how to do it. Sorry man.

 

[Murray]

but for this you can't just lower the sound potentiometer or sound volume directly to the board?

It won't really lower it enough. Just build the attenuator circuit. It's not hard and definitely worth it for the peace of mind.

Either that or run your sound at line level from before the amp, but that's not really supergun scope. My current supergun doesn't handle the MVS's stereo out at all (but does have an attenuator for normal mono JAMMA). Instead, I run stereo cables from the board's headphone jack.

 

[Rengoku]

this is my scart wiring

scart/jamma

15 - 12 (red)
11 - N (green)
7 - 13 (blue)
20 - P (video sync)
4 - 14 (ground)
6 - L (speaker L)
8 - 6 (12V)
2 - 10 (speaker R)

this handle both mono and stereo, i tried with an mv1f and a 4slot one and the sound switch properly

i think (and mkl told me) that is due to the fact that TV use always a ground for the speaker negative 'cause is wired as stereo and in case of mono audio from the sg nothing changes

on scart pinout i found over the net i can read that pin 16 need a 1-3 V signal to switch between AV mode and RGB mode
i can't understand this and where i can take that line

and for the stereo attenuator..how i proceed?

 

[Rengoku]

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