PC Engine / Turbografx16 s-video mod

[chipperkwah]

Wanting to get dirty with some s-video on my Duo R, wondering if anyone has done the mod on their duo and taken photos of it? I assume that the R130 resistor should be easy to find, but I haven't opened it up yet to check. Too busy with blood gear. Also, if I remove the stock din and replace it with an s-video din I'm not sure how I would go about getting audio. I could always replace it with a din that has plenty of pins and make a cable that terminates in s-vid and stereo rca, but that's a pain. Anyone have a better idea? Would rather not drill holes to make room for new audio jacks.

[ProfessorProfessorson]

Wanting to get dirty with some s-video on my Duo R, wondering if anyone has done the mod on their duo and taken photos of it? I assume that the R130 resistor should be easy to find, but I haven't opened it up yet to check. Too busy with blood gear. Also, if I remove the stock din and replace it with an s-video din I'm not sure how I would go about getting audio. I could always replace it with a din that has plenty of pins and make a cable that terminates in s-vid and stereo rca, but that's a pain. Anyone have a better idea? Would rather not drill holes to make room for new audio jacks.

Alternatively you could hit up this thread:

http://www.pcenginefx.com/forums/index.php?topic=13044.0

Drakons fled the scene so to speak, rather wishing to focus on trashing peoples efforts on his own forums and taking credit for others work elsewhere I was last told, so I don't think he would be able to help you out on his mod here. This is basically one of those threads better left to die. If you do want to discuss Drakons method and how to improve it, you can google his name and you should come up with some results showing what forums he is currently on or something so you can contact him directly. If you're really lucky too, he may offer to do the work for you for about 400 bucks or so. He may, or may not, include even drilled holes with the modwork. That might cost extra.

[chipperkwah]

Ah I see. I had previously read through your thread as well and it seems that both circuits are almost identical, except that yours uses a cap as a filter while this mod opts to remove the resistor in order to get a clean chroma signal. I feel like both methods should yield very similar results, someone correct me if I'm wrong. I must say though that the schematic photo you made is much nicer looking. I would have to pass on his $400 mod fee , as I'm perfectly capable of doing this myself. Sorry to revive an old topic, seems as though there was some bad blood associated with this in the past.

[thesteve]

alternately the cap is optional, as most displays should just ignore the luma on the chroma pin.
several DUO mods have been done, adding the connector to the back of the unit

[chipperkwah]

alternately the cap is optional, as most displays should just ignore the luma on the chroma pin.
several DUO mods have been done, adding the connector to the back of the unit

I know you're the resident video guru, so in your opinion would it be best to pull the resistor/cut the trace or use a cap on the chroma line? Just curious, since it seems like both ways work. I wasn't aware that most screens would ignore the luma anyways, good to know.

edit: I have no interest in using composite video again once I do the mod, so I'm not bothered if getting rid of the resistor gets rid of composite.

[NightWolve]

I know you're the resident video guru, so in your opinion would it be best to pull the resistor/cut the trace or use a cap on the chroma line? Just curious, since it seems like both ways work. I wasn't aware that most screens would ignore the luma anyways, good to know.

edit: I have no interest in using composite video again once I do the mod, so I'm not bothered if getting rid of the resistor gets rid of composite.

There's a simple pro/con to it. A clean Chroma signal that isn't contaminated with Luma at all will be better than using a filter cap from a Composite signal where both have been mixed in. So yeah, if you disconnect the Luma (break resistor/trace) from the Composite amplifier, all you'll be getting out of the Composite output is a clean and properly amplified Chroma signal which will be perfect for S-Video use. The con here is that you're breaking default Composite support, so you can either build another circuit/mixer to maintain it or not care. Since you're indicating that you don't care, then I'd say do it this way. You'll get the best S-Video signal, but will break Composite support. If that trade-off is acceptable to you, then this is the best way.

[chipperkwah]

Right on, thanks for the info guys. Very excited for some crisp s-video. Not that the duo composite is particularly horrible, but might as well have it looking as good as possible.

[NightWolve]

You know, I thought of something. You don't have to really break Composite support over this and there's a much better way than building another circuit. Back when I was inspecting new LCD TVs to see how many had S-Video (very few nowadays), I noticed a trick they did to save space in supporting both Composite and YPbPr Component signals:  Instead of 4 RCA jacks (yellow, green, blue, and red), they reduced it to 3, but the green jack for Luma was colored half green/half yellow to indicate that it accepted a Composite signal and thus would digitally switch to it if detected.

Based on that idea, when I did my SNES Component mod, I drilled the holes for a triple RCA jack mount (green, blue, red) but I also bought a little switch and later added that, so when the switch is on the Luma side, Component works, but when I flip the switch, the same green jack outputs a regular Composite signal. This way, I didn't have to drill a big 4th hole for a yellow RCA jack for Composite.

Anyhow, based on this idea, all you need is a simple switch. You'd find that resistor (or trace) that delivers Luma into the Composite mixer/amplifier, you'd solder off one end, then solder wires from and to, and those wires would go to the manual switch (placement would have to be determined, next to the S-Video jack perhaps), etc. OK, so idea is, when you're using S-Video, the switch is in the off position, disconnecting Luma from the Composite mixer, but say you get a new TV which doesn't have S-Video support, boom, just flip the switch and now default Composite support is restored.

I was asking steve something more complicated and needless (which I see now) in the other thread, which was what's the best way to build another circuit to maintain Composite support. But, that idea is totally replaceable by the switch idea and there's no possibility of contamination... If you don't mind buying the right switch and drilling another hole for it, it'll do the trick just fine!

[EvilEvoIX]

I need to get my TG16 modded.

[chipperkwah]

Anyhow, based on this idea, all you need is a simple switch. You'd find that resistor (or trace) that delivers Luma into the Composite mixer/amplifier, you'd solder off one end, then solder wires from and to, and those wires would go to the manual switch (placement would have to be determined, next to the S-Video jack perhaps), etc. OK, so idea is, when you're using S-Video, the switch is in the off position, disconnecting Luma from the Composite mixer, but say you get a new TV which doesn't have S-Video support, boom, just flip the switch and now default Composite support is restored.

That's an excellent idea, it would be ideal if I could have both. Looks like I'll be drilling an extra hole.

[fsa]

I need to figure out where to mount a S-video connector on a CG unit, I suppose I could replace the 5 din connector with an 8 din and make two pins s-video (with a custom s-video cable). With the CD-unit that I have there really aren't that many options on locations to install. I assume s-video works fine in conjunction with CD-rom unit.

I have been toying with the idea of using a female 3.5mm stereo plug and build a custom Svideo cable with a male 3.5mm on one end because the female jack is much smaller and easier to install ( the ones with the with the small ring screw).