Genesis external S-video converter help

[Push Upstairs]

I have the idea in my mind to make myself a external S-video converter for a Genesis 1.

My idea would look something like this:

http://usera.imagecave.com/Push_Upstairs/Misc_Pics/S-videoDiagram.jpg

The chip inside the box is a Sony CXA1645 which (looks like it) can convert analog RGB to an S-video signal.

My question is, aside from the RGB in and S-video out, what else would I need to hook up to this chip?

The specs on the 1645 are at http://www.datasheetarchive.com/datasheet.php?article=1218617 (PDF file).
Genesis A/V pinout:
http://www.hardwarebook.info/Sega_Genesis/Master_A/V

I know squat about building electronics, so help me correct this deficiency

[Push Upstairs]

Anyone?

Am I on the right track with this idea, or am I dreaming up something that clearly tests the limits of modern science?

[agbulls]

I still want to get my Genny working with an S-video cord...but don't have the $ to pay someone to do it for me right now. Your solution looks to be a simple way. However, I'm pretty sure it won't work. Here's why:

Once the video signal leaves the system via that output, its already been degraded. The only way to get a true S-video signal is by performing the mod. Fabombjoy would know for sure--he's the modding king around here.

[Push Upstairs]

If the signal is degraded, then how do SCART cables and home made RGB cables still manage to make things look good?

[davidleeroth]

Well, you'd need power and sync for starters.
There are some projects in the net using the CXA1645 like this:

http://www.nexusuk.org/projects/rgb2svid/

Just as in the project above, if you're building an external converter, why not build something that has RGB in via SCART or other generic connector? It'd probably be easier too, as MD/Genesis 1 RGB SCART cables are available and you could use it with other consoles just by buying the appropriate cable.

[davidleeroth]

If the signal is degraded, then how do SCART cables and home made RGB cables still manage to make things look good?

Warm chocolate pudding, aka RGB, is not degraded.

[JLukas]

Micomsoft (the company that makes the XRGB boxes) released an adapter exactly as described in the original post. Here's a great link with more info on it:

http://www.segagagadomain.com/hardware-mega/xmd-3.htm

That's the XMD-3, which is for the model 2 Genesis, Nomad, and CDX. The earlier XMD-2 and XMD-1 are for the original model 1 Genesis.

They are pretty rare and expensive, however. It would be much cheaper to have a professional mod your system and you also won't have an external box laying about.

[Push Upstairs]

I really didn't want to go the S-video mod route as I can't really think of a decent spot I'd like to mount it and I'm really happy with keeping the
full functionality of my Genesis (Power Base, Sega CD).

Also the idea for this was to try my hand at making something because I've never really made something like this before. Plus this project was always going to be a "Genesis only" ordeal because I can get myself S-video cables for a Saturn and SNES so there wouldn't be a reason to make it for use with them also.

But going back to technical specs, Sync and power...ok...the chip specs list a spot to connect the power and sync, but I don't see a spot for sync out for the S-video.

Any ideas?

[FABombjoy]

I really didn't want to go the S-video mod route as I can't really think of a decent spot I'd like to mount it and I'm really happy with keeping the full functionality of my Genesis (Power Base, Sega CD).

I use the Power Base Converter & Sega CD on my s-video modded genesis without any trouble. As long as you don't mount the jack in a spot that interferes with the PBC, there's no problem.

[omnedon]

ditto the above.

You would be blazing new territory with what you suggest, at least as a homemade project.

[Push Upstairs]

I'm fine with all that.

I was just wondering if anything had any tips as far as if I needed any transistors or resistors. Basically, I'm terrible at reading circuit diagrams.

I'm also worried that there is something that guy included in his converter that I really just won't need. Obviously I don't need to hook a SCART connector up, but I wonder if any other extraneous (at least for my idea) were used for his project since it is PAL.

[gcl1984]

this should give u all the info u need:
http://gamesx.com/wiki/doku.php?id=av:sony_cxa_series

[Push Upstairs]

I'm sure finding a CXA2075 would make things worlds easier, but i have no idea where to find one of those. :-/

[Push Upstairs]

Anyone have any experience with a similar chip called AD724/AD725?

I've read the data sheet for each and it looks like it can do what a CXA1645 can do without the need of an external filtering for the s-video signals.

[jackflack]

I f you have a Model 1, you don't have a Sony CXA1645 chip inside. Only Genesis Model 2's with Model # MK-1451 on the back nad Model 3's have that chip inside.

What kind of signal you trying to get out of your model 1? RGB,S-Video?