PC Engine / Turbografx 16 s-video mod

[Drakon]

Video signals come from the huc6260 chip

 

 

Revised circuit:

New demo capture:

http://www.youtube.com/watch?v=uoA_9Qmx_B8

Edited July 27, 2012 by Drakon

[Rex Dart]

Yup, I saw this on some PCE forum & was going to give this a shot over the weekend. Surprised it took so long for somebody to figure this solution out, but I'm glad they did.

[Tempest]

S-Video is alright, but RGB is where it's at!

[Rex Dart]

Eh, all component video signals look the same on my SD CRT anyways. Maybe if I were feeding the signal into some sort of snazzy monitor...

[Rex Dart]

Yup, I saw this on some PCE forum & was going to give this a shot over the weekend.

 

Actually, this is slightly different than the one I'd seen; they used a 1pf capacitor on the chroma line. Wish I knew enough about analog & A/V electronics to know why.

Edited July 29, 2012 by Rex Dart

[Drakon]

The other circuit is different. My circuit disconnects composite video and rf but gives the cleanest s-video possible. The other s-video circuit the luma is getting mixed in with all the colour lines so the cap is supposed to "filter out" the colour information. The whole idea behind s-video is that luma (brightness / intensity) and chroma (colour) are separate which is why in my mod I separated the two. Once luma and chroma become separated you no longer need to "filter out" the chroma that's mixed with luma and vice versa.

 

Yup, I saw this on some PCE forum & was going to give this a shot over the weekend.

 

Actually, this is slightly different than the one I'd seen; they used a 1pf capacitor on the chroma line. Wish I knew enough about analog & A/V electronics to know why.

[Rex Dart]

Ah, I see that now.

Any way to tweak it so that it still allows for composite video along with your s-video?

[Drakon]

Leaving composite video working would most likely decrease the quality of the s-video because you're leaving all the signals mixed together. The whole point of doing this mod is so that you don't need to use composite video anymore.

[Rex Dart]

Sure, but other systems & mods manage it... with fewer & fewer TVs supporting S-video, I'd like to have both options.

A switch would work, but it's not very elegant.

[Drakon]

Other systems don't generate composite video by combining s-video signals in a circuit like this one. There's ways to wire it up to have both I'm sure but I never bothered since I hate composite video. If you wire it up for both most likely you'll lose a certain amount of image quality in s-video.

[Uzumaki]

I'd still like S-Video out on as many systems as possible if it's supported internally like the TG-16. If the future TV leaves out S-Video, usually S-Video to HDMI will suffice.