S-video Vs. Composite detection on TVs. Could you guys do a small test with your TVs?

After my first successful attempt at a purely composite design, I want to make a new single cable circuit mod for the Tototek GBA-SNES, Retrogen adapters and the likes. However, this mod would not be possible/practical on all Tvs, only on some. I would like to have an idea if this would work on most TVs or not.

Let me explain.
This mod should allow you to play SNES games in S-video as well as Clone-in-a-cart adapters like Tototek Ad adapter in composite with a single cable.
Only a single cable would be connected to the TV. Everything would work seamlessly without you needing to mess with cables.


The Idea is to use a SNES cable with both S-video and Composite, those are fairly common for the SNES. Or you can make one.

TVs usually have s-video input on a shared channel with a Composite input. So both would be connected at the same time, like in the picture.


Now the Problem:

When both Composite and S-video Cable are connected at the same time, all tv's I have tested will favor S-video. However they can do this in at least 2 different ways.

A: Some TVs will detect the presence of a signal in the S-video input and will switch to S-video mode only upon detection of a signal. This means that you could have a loose S-video plug connected to the input and Composite would still work unless you sent a signal to s-video. My mod would work with those TVs. So far 3/5 tvs I tested Are Like this.

B: However 2/5 TVs used the S-video Jack as a switch. As soon as you connect to the S-video port, the composite is cut off. The mod would not work with those, unless you manually disconnect S-video when you want to use the Clone-in-a-cart adapter, which defeats the purpose.

If it is discovered that most TVs are type A, it makes the mod much more interesting that if most TVs are Type B.


The Test:
It is very simply to make a test, all you need is a composite source connected to a TV and a spare S-video cable connected to nothing. It can be a straight cable or a console cable.

Just have the Composite signal display on the TV and try to connect a loose S-video cable to the corresponding input. If this changes nothing, your TV is Type A.
If the screen becomes black, your TV is type B.


I would appreciate if people could do this since I can only test so many TVs myself. If you have everything needed on hand, and I believe many people here will This test will really take less than 2 min to do. If you don't have all needed on hand and/or think this is a hassle, don't feel bad about it

Also, if you do the test It might be interesting to share the brand/model of your TV along with the result. I wanted to assume that High end TVs are type A and low end are B but on the five I tested there are no correlation so far.

 

My old Toshiba CRT is the switch type, same for my Sylvania LCD, the switching is usually done by the plastic orientation pin on the svideo connector.
FYI some TVs can process a composite signal properly via the luminance pin of svideo, I found that out when I got scammed on a Svideo-Composite adapter that lacked a conversion circuit.

 

I can tell you that my PVM certainly doesn't. It doesn't auto-detect shit. You even have to manually enable PAL60 for composite sources running as such, otherwise the colours are all screwed up.

Totally worth it though.

 

My Samsung 32" LCD is Def a Type B, it actually changes the channel ID from "AV" to "S-Video" when the S-video cable is inserted.

 

My Visio 32" is type A I always have inserted an svideo cable and composite and it display composite until I send signal to the svideo.

 

Thanks for all the replies, I posted this on 2 forums and it would seem so far that a small majority of TVs are type B, yet the sample is still too small to say that for sure.

One thing appears evident though is that both types are relatively common.

I made the schematic for the circuit and have all the parts. As I said earlier, this would only work with "type A" Tvs.
Will try to build and test it tomorrow.
Schematic posted here:
http://www.assemblergames.com/forum...adapter-does-not-need-separate-AV-cable/page3

 

Regarding those S-Video cables that come with a yellow cable, you'll have to rewire the cable for it work properly. I was burned a few times because of this, but I after opening the cable at the end and soldering in the correct wires, these cables work fine, though could be better.

 

Haha, yes, I found that out the hard way too.
I had even started a thread about this.
http://www.assemblergames.com/forum...cted-to-Composite-Video-on-Snes-s-video-cable


But I also have an Intec multi-console cable ( works on PSX, GC(SNES) and XBOX ) that has both S-video and composite.
And this one seems to be wired properly as I get beautiful S-video on my SNES with it.

 

Why not play the games on your TV through an emulator? The picture will be much better than from a real snes via s-video.

 

Heresy!!!

 

this, if you're going to use emulators why bother with a tv? just use a computer monitor and some filters here and there

but the real deal is on the real console with a tv, you cant beat that feeling

 

My TV has separate inputs for S-Video and Composite (one's on back, the other front), so I'm not sure how much good it could do.