HomeMVS (Part 2)
The RGB Converter
Yes, the hardest part of the whole project. The MVS board outputs RGB and
Sync to go to a arcade monitor. You have to convert this to work on a normal
NTSC (American/Japanese) TV. If you have a European PAL TV, your life is easy,
since you can just wire up a SCART
connector and have it work with out a converter.
But if you're like me and live in the USA, you have a hell of a job to wire
up. You need to build a circuit to convert the RGB and Synch signals to Composite
Video (the Yellow RCA plug on the back of your TV) or S-Video output (If you
have it, you'll know it). My converter (and most out there) will provide simultaneous
output of both composite and S -Video.
For my converter I used a IC from Analog Devices, the AD725. You can use different chips, but I found this one to be easy to obtain. It was also relatively easy to implement. However almost any chip you find will be a surface mount meaning it'll be hard as hell to solder that puppy up. Fortunately, there are adapters out there that will make your life easy. BTW, you want to get the WIDE SOIC adapter for the AD725 and family chips. You'll have to find a distributor for the adapter, but it's not hard to find from there site. Unfortunately, I didn't realize this until it was too late and I had already hand soldered leads off the IC. Fortunately, once you get all the parts, you can wire up the circuit that is in the Data sheet and it will work just fine with your MVS. But you must get your hands on the IC itself, which is kinda hard since Analog Devices doesn't sell the chips individually, they sell them in huge lots to other companies. I got mine as a free sample (2 from having my Professor order some, and 2 from working at a electronics company), so it worked out nicely. If you aren't a student or work for a company that deals with electronics, you can try a local electronics shop and see if they have any in stock (one close to me had the AD724, which is almost the same thing as my chip and will work just fine if it's what you can get).
Now I'm not going to go into specific detail on how to wire up this converter on a bread board. What I will give you is the circuit schematic. This was taken directly from the data sheet PDF that is available on Analog's website. Basically I think that if you can understand this schematic then you're capable of physically soldering it up nicely. If you can't understand it, then I recommend finding a teacher at your school or college who can give you a hand. Hell you may even get some extra credit depending whether you can actually use this for a class or something. But if all that information just scares the crap out of you, then head to www.jrok.com and pick up his RGB to NTSC encoder to be used w/ arcade boards.
I did not implement the "Y-Trap" part of the CKT that is shown on the data sheet. It works fine with out it and the picture quality is still very good. Here you can see a final picture of my RGB converter with the Wide SOIC adapter.
You'll notice I used power supply connectors to hook up for power and to
make the video out connection. This makes the circuit modular and easy to
modify/fix should any problems arise. You'll want to run the wires to a Composite
video connector. This is done by running the actual voltage cable to the
inner connector, and you're video ground to the outer connector.
The Physical Enclosure
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This can be left up to you. I unfortunately had to make mine quite large, however depending on what MVS board you buy you can make yours large or small. It all depends on what you want. However there is one thing I can recommend for you to do, the Joystick pinout.
You have to make some kind of connection for your joysticks to plug into you're SuperGun. You can do whatever you want but the way I did it has some nice advantages. I designed it to use a DB-15 connector, much like the one you'd find on the Neo Geo AES/CD systems. I also used the Neo Geo pinout as a base for my controller. This way you can plug in an AES joystick to you're SuperGun and have it work flawlessly. Check out my Joystick page for the pinout.
Modifications
MVS 4X Bios Mod
This is a "mod" you can put on your MVS board, the 4X MVS Bios is almost like a wonder tool. With the addition of two switches, you can select the region of your Neo (USA or Japanese), and you can even make most MVS games think they're being played on either a MVS or AES system. So you can enjoy all the extra options and features you would have if you had the AES version of a particular game! Or you can switch it back to MVS for more compatibility, and the good old arcade feel. The place to get this is from Jeff Kurtz at Neo-Geo.com. For a good installation guide for this, head to HardMVS.
The Game Select Switch
If you have a multi-slot MVS board one cool little feature you can put in is the Game Select button (not to be confused with the Select button on the AES systems). Basically this is the switch you'd find on multi-slot cabinets that let you switch games while they're running in demo mode (before you actually play the game). It's really cool to have and it is nice to just switch games after you're finished one game. I mean who wants to go through the effort of switching carts?
It's not hard to do, all you do is wire up a normal arcade button the way you normally would and put the output either pin d or pin 26. It doesn't matter which one cause the games will cycle around in a circle. See, not that hard to do at all!
Pause Switch
Well I came up with this cool idea to use Dip Switch 8 as a pause switch, but I don't have the time to implament it. But my good friend Briggs at HardMVS did have the time and made a really cool mod for your MVS cab that is also applicable to the MVS supergun. So go over there and check it out!
That's about it for my HomeMVS setup, head over to my Universal
Joystick page for more information.
