Video Converters for super guns

What are the different types of video converters (NTSC) that are available for making super guns? I know I've seen a few different kinds, but I can't remember where I saw them.

There are 3 different major kinds:

JROK S-vid and composite

R2N S-vid and composite

Neobitz S-vid, composite and Component

Cool. Thanks broken!

anyone know of directions for building your own? All the video converter chips that I have been able to find require the sync to already be at NTSC or PAL frequencies.

From experience, I highly recommend the JROK converter. Video quality is fantastic and support is top-notch. James really went the extra mile helping me diagnose what turned out to be a ground loop problem in my home A/V rig.

Also from experience, I would not recommend attempting to build your own converter. There are some schematics floating around the net but the prefab ones are proven designs and any money saved is quickly offset by wasted stress and time.

Which encoder you use depends on what you want out the end.

JROK - Sony CXA-based chip and works great with many boards. It is, however, incompatible with a small percentage (can't remember which)

R2N/NeoBitz - both are AD724/5 based and work similarly for S-Video and composite with the obvious difference being the component video circuit. Most find that the Analog Devices IC works best for Neo Geo, but is incompatible with more boards that the CXA chipsets.

I myself use all three of those encoders, depending on project. High end superguns I always go with the NeoBitz since the component video has very very high compatibility and the S-Video/composite is treated as a bonus. R2N for Neo projects that component isn't needed. JROK for standard superguns.

I build my own encoder from scratch as well, based on the Sony CXA chip. I use it nearly exclusively for Turbo Grafx/Duo/PC Engine applications and it's awesome. Why don't I use the JROK then? Myself and others have found that the JROK has some issue with these systems, which I'm trying to solve. The hardest part of building your own encoder is getting a good chip for it and then wiring it. The 1645 requires more connections that the 2075 version, but works well when properly installed. I have my process down to 50 minutes per encoder.

Interesting... Thanks D-lite!

When you build your own, do you just build your encoders on strip board?

And thanks Murray, but I have quite a bit of electronics experience, so the time and frustration is something I don't have a problem with. I actually like the challenges!!

UncaJJ said:

And thanks Murray, but I have quite a bit of electronics experience, so the time and frustration is something I don't have a problem with. I actually like the challenges!!

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Ah, sorry. I made the assumption that since you didn't know about the encoders in general that you probably didn't have the experience to build one.

I tried to build one based on the AD725 reference (AD725 becaue I couldn't get any Sony chips). After a couple weeks of refining schematics and pcb layouts, the end result was a burnt IC (late night / careless mistake). I ordered the JROK shortly thereafter ... I was just ready to spend time playing games rather than fighting with the parts.

Of course if you have the skill / resources to build a good Sony encoder, go for it.

I've seen them on both stripboard and normal perfboard. No reason get fancier than that, really, unless you need things small.

No prob Murray. My first computer associates degree was more than half electronics, but I never worked with video encoders before. I want to get pretty fancy with a super gun, and want to be able to combine video and audio on the same board, as well as some possible switches... *shrug* depends on what the chip specs are I guess...

Anyone have a datasheet or pinout for the cxa2075 in pdf format?

There is also the XRGBII for VGA.



And there is an RGB->Component Converter that uses an SCART socket.
Very good for supergun use. As good as a Neobitz.

D-Lite said:

Most find that the Analog Devices IC works best for Neo Geo, but is incompatible with more boards that the CXA chipsets.

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So CXA is more compatible if you can get it, but the AD has componant out? hmmmm...

norton9478, I'll look up XRGBII, thanks for the info.

No, the AD chips don't have component out (AD724/AD725). I think the NeoBitz encoder uses a custom circuit for the component output.

The JROK is compatible with pretty much all boards. The exception most people have are the Midway games like Mortal Kombat, NBA Jam, etc. However, those incompatibilities are caused by the TV they use it on, not the converter. The JROK board itself works great with those boards if your TV can handle the weird refresh rate those games use.

Yeah the Neobitz is 2 different video encoders on one board. The great thing about this encoder is that if the component video doesn't work on some PCBs, there is a chance that the S-video/Composite will work or vice versa. I say go with the NeoBitz if you want overall compatability. Of course I am sure you will run into some pcbs that won't work on it at all. I am sure these are those weird games that have a slight lower signal like 14.6 instead of the 15 for example.

When using the NeoBitz, use a Sync Seperator switch.

norton9478 said:

When using the NeoBitz, use a Sync Seperator switch.

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What's a sync seperator switch? splitting the c-sync into v-sync and h-sync?

What the???????

NTSC video timing (15.75KHz Horizontal)

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So I've been dismissing chips because I thought that standard resolution was at a different frequency from NTSC and the chips said it must be at NTSC already????

ARG! Now I need to find that chip I liked again so I can test it out!! AAAAAH!