Author Topic: DIY supergun questions  (Read 1652 times)

Offline gsl

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DIY supergun questions
« on: June 03, 2009, 05:21:17 PM »
I think this is technically arcade-related, but apologies if it should have gone in the Off-Topic section.  I'm finally knuckling down to putting together a supergun, and as I figured a few members here must have something besides a dedicated cab to play their Cave (and other) boards, I thought it would be a good place to ask.

Now, I know rigging together a supergun is as simple as following one of the infinite wiring guides online, but I'm pretty stupid when it comes to electronics, so I figured I'd ask.  First, I get the impression that the standard audio output from an arcade pcb is Very Bad for a regular TV; what needs to be done to get it to not blow the speakers up?  Also, what's the best method for getting the video signal to a NTSC TV?  There's no way I'm going to be able to rig up my own encoding circuit, so is going with something like a J-rok prebuilt encoder the best option?  Finally (really stupid question), how would I specifically wire up a power switch?  Do I need something that cuts the +5, -5, and 12v lines all at once?  What about ground?  This may be pretty obvious for someone with even beginning electronic skills, but I can't quite find any sort of reference which explains this in concise, clear language for idiots.   Most Internet info seems to assume you're already some kind of electronic engineer.

Thanks for the help!

Gwyrgyn

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Re: DIY supergun questions
« Reply #1 on: June 16, 2009, 01:38:46 PM »
First, I get the impression that the standard audio output from an arcade pcb is Very Bad for a regular TV; what needs to be done to get it to not blow the speakers up?
Not really no. All you need to do is run the right wires to the output and you can just plug it in as normal. Make sure you adjust the volume on your PCBs before you turn it on though, just to be safe.

You've probably read about those 'audio attenuation' circuits some people put into their superguns. These things are worthless and only cause problems. I guess at some point there might have been a reason for them, but I don't know what it is.

Quote
Also, what's the best method for getting the video signal to a NTSC TV?  There's no way I'm going to be able to rig up my own encoding circuit, so is going with something like a J-rok prebuilt encoder the best option?

Yeah, I'd stick with a J-Rok to make life easy. Not sure if there is any particular versions you do or don't want though.

Offline gsl

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Re: DIY supergun questions
« Reply #2 on: June 17, 2009, 05:05:41 PM »
Thanks for the reply.  You mention PCB volume; do most PCBs then have a volume dial/slider?  All I've got right now is a Neo-Geo MV-1F and I do recall seeing some sort of volume slider there, but I always assumed it was for headphone volume.

Speaking of Neo-Geo, while I know my model only outputs mono sound through the harness, do most PCBs output in mono, or are some in stereo as well?  Are there any decent guides or wiring diagrams as to how one would set up to switch between mono and stereo output?

Apologies again for the idiot nature of the questions, but for as simple as constructing a supergun is (basically just running wires between components) it's hard to find much in the way of super-beginner advice.

Gwyrgyn

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Re: DIY supergun questions
« Reply #3 on: June 17, 2009, 06:55:53 PM »
Anything that's actually JAMMA is in mono. There are some notable exceptions, like MVS does stereo as does a lot of Capcom hardware. All PCBs I've owned have had a sound volume pot on them, but I'm sure there are some out there that don't. It's probably not something you will have to worry too much about.

Back when I was working on my supergun I had some issues getting the wiring for sound right. It turned out that to get mono sound wired directly to a pair of 8 ohm speakers, I needed to wire them to pins 10 & L. However to wire sound up to a normal RCA jack, I needed to use 10 & GND instead.

I've never tried to wire for stereo so I'm not sure how it works exactly. I think you should be able to just wire one RCA jack to 10 & GND, and one RCA jack to L & GND. But, I'm not sure how this will react when trying to run a mono game on this setup. I'll see what info I can dig up about this.


The main thing to worry about with sound is that the audio coming off the PCB is amplified already. This means it's good to plug into unpowered speakers (like a loose 8 ohm speaker or a pair of headphones) but can be trouble if you run it into a TV (which assumes the audio coming in is NOT amplified). The solution as I said is to just make sure you drop the audio on the PCB down to minimum before you turn it on, then turn it up to a proper level.

Offline gsl

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Re: DIY supergun questions
« Reply #4 on: June 22, 2009, 05:42:04 PM »
Thanks again.  That was one of the more mysterious issues I've come across which doesn't seem to be clearly stated anywhere.

When you did the wiring for all of your button connects and socuets, did you solder or crimp most of the connections?  My soldering is a bit sloppy, especially on small things like DB15 cups, and I'm wondering if it's possible to go completely solderless and get better connections with crimping.

Gwyrgyn

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Re: DIY supergun questions
« Reply #5 on: June 23, 2009, 12:37:01 PM »
One possible answer is you could buy some short male DB-15 cords, cut them open, and use those to make the ports in the supergun. That way you don't have to solder the ports at all. If you are starting from a prewired jamma harness, you can run all of the wires for the controllers from the harness into something to join them with the wires from the control input, like a terminal bridge or a fingerboard with traces on it. Using a terminal bridge is big and might be messy but it would mean no soldering required at all for the controllers.