Where can I tap a sync signal for s-video?

[HercTNT]

You have component "in" your duo's?

[Duo_R]

Well RGB amps internally to a modified AV port sends RGB to the Atlona box which converts Tje RGB signal to  component video. So it isn't internal although I could internalize if I wanted to.

[pdiggitydogg]

I just made a diagram to help those of you out who want to upgrade your video to S-video. Especially since I was confused myself when I first did this without seeing any pics. There is also info on where to tap the needed signals for both a DUO system or a standard TG16/pc engine.

Sorry to bring this back from the dead, but does anyone have this diagram from Keith?

[SmokeMonster]

I'd love to have the diagram too if anyone has it saved.

[Keith Courage]

I didn't realize it was down. Uploaded it again here. Also, I have found that for a US Turbo DUO or Black PC engine DUO it is best to get ground from the AV port. Tapping it from the sheild or common ground on the board itself doesn't produce as clear of an image. There is also another good place to get 5V and Pin 40 for the collector straight from the Hu6260 chip inside a DUO that I like to use instead of the AV jack now but the AV jack still works just fine. It's just personal preference where to tap some of the signals from.

[NightWolve]

Steve's suggestion for the best place to ground your video circuit is right at the Huc6260 chip itself which would be pins 55+56. Are you suggesting otherwise in having tested the AV port versus pins 55+56 ? Also, best undisputed tap for a 5V source is the output pin for the regulator. Clean voltage right from the source not having gone past many traces to get to the AV port or wherever else you might tap it.

[Keith Courage]

Yeah I've tried the two pins mentioned off of the hu6260 for the ground. still produces a slightly blurry image with a US duo on my TV. ground from the AV jack is the only place that seems to fix the issue. I've tested it with many US DUOs. I would also like to add that tapping the av jack ground fixed issues with the component video mod showing big white lines as well on US and JP Pc engine DUOs.

Could just be an issue with my TV as well.

However, I've been able to use any ground for a turbo grafx, white pc engine, and duo-r without any issues at all.

[thesteve]

the prob is the ground on the AV jack of the US duo
run a wire from AV ground to 6260 ground

[NightWolve]

Hmmmm, thanks for info then Keith... Guess I have to work this info into my photo guide somehow... :/

[existensmaximum]

yes the chroma could be cleaner (its from pin 20 inverted)
the cap cleans the signal (smaller cap cleans it more)
i just used a cap and transistor i had handy

Hello! I'm doing this mod soon, and I have a couple of questions first.

1, Earlier in the thread, you said that any NPN transistor will do. Is that true? Any? Could I try with any NPN I have lying around at home, or could I damage something..?

2, Would an even smaller cap clean the signal more? I would need to buy this capacitor anyway so I could just buy an even smaller one than 0.001 uF. Same question here - could I damage anything by choosing the wrong value?

[thesteve]

Yes any NPN you have should work
The cap I stated should be the smallest  you can use