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S-video & Composite mod for Colecovision


strattsp

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Alright, so I've done the S-video mod from lab rat's site : http://www94.pair.com/jsoper/cv_svideo.html

 

Since I'm a lot better at following electronic schematics than writing them,

The question is:

What do I need to do so that the composite output and the S-video output can co-exist without interfering with each other? I was thinking that maybe I needed to push the output signals through some diodes, and a friend suggested maybe using and optical isolator chip.

 

Any suggestions?

 

Thanks,

Steve

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I'm not in IEEE either so I'm better at following the schematics then making them up.

 

Would you need to use both simultaneously? If no you could probably install a simple mechanical switch to combine luma/chroma for compsosit and seperate them for s-video.

 

Just a thought anyway.

 

I installed a composite mod on my CV, but haven't don't the s-video yet. None of my TVs support it, so not much use to me.

 

Good luck with it!

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I think although a mechanical switch would work, it is not elegant, and I would only do that as a last resort. I had an EE at my poker club suggest using ferrite cores to remove the interference. I'll give that a try and report back. Any other suggestions would still be welcome.

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What do I need to do so that the composite output and the S-video output can co-exist without interfering with each other? I was thinking that maybe I needed to push the output signals through some diodes, and a friend suggested maybe using and optical isolator chip.

I don't remember (and don't want to look right now), but I probably used his as a reference when I did my own S-video mod a couple of years ago.

 

The main thing I remember was that the S-video needed an amplifier. I happened to have a few op-amp chips (LT-1211, I think) which had video bandwidth, and used one of those. As long as you amplify the S-video tap, it shouldn't mess up the composite or RF.

 

I need to do my mod again. A friend of mine has shown interest in having a modded console, and I really should document what I did. I didn't do a composite output, though. And that was all before I learned how to get circuit boards made, so I might be able to make a real nice mod now.

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I've had problems with washed out colors using the Heckendorn mod. Although it is much easier to do, I think it tends to be very sensitive to the voltages. The other mod produces much more reliable results. I am pleased with the mod, I just need to figure out how to make the composite and the S-video coexist.

 

By the way,if you take the audio signal from the place Ben Heck suggests, you will not get audio out when you use the Atari 2600 expansion module. You need to take the audio signal from inside the RF box, then the audio out will work properly.

Edited by strattsp
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By the way,if you take the audio signal from the place Ben Heck suggests, you will not get audio out when you use the Atari 2600 expansion module. You need to take the audio signal from inside the RF box, then the audio out will work properly.

 

That's good to know. I'm using Ben's mod on my CV, didn't have any trouble with colors. Don't have the 2600 adapter as of yet but if I end up getting one guess I'll have to rework the mod to get audio from inside the RF modulator.

 

Thanks for the info.

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  • 1 month later...

Here's another problem...

 

So I am doing the s-video mod, and I can't get the 2600 expansion to work. I know the expansion module is good.

 

Anyone have any thoughts?

 

I am thinking it has something to do with cutting the trace inside the RF box. I know the 2600 expansion works with the composite video mod, but it doesn't work with the s-video mod.

 

I know it can be done, the problem is that I an an ME, not an EE.

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I have solved the problem. I have figured out how to have composite and s-video co-exist without needing a toggle switch between them, and you can use the composite output with the 2600 expansion module. :cool:

 

I am working on a website that will describe the procedure, as well as offer DIY mod kits, and mod services. I'll let y'all know when it's done.

 

-Steve

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