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

[thesteve]

the picture intensity can be adjusted by changing the resistor value (less resistance= brighter picture)
the transistor chosen will effect contrast just a little.

[grahf]

That's pretty cool, I've never heard of that before now. I'm really interested in seeing how it looks.

[thesteve]

i tested it on 2 monitors last nite using a 47ohm resistor.
1 was perfect, the other a bit clipped.
they both looked good, just my Y signal was super hot (too much for 1 of the displays)
the 100 was somewhat a guess.

[ApolloBoy]

What would the signal be like with a 75 ohm resistor?

[thesteve]

solid, might be too hot depending on the transistor

[Bonknuts]

ya could go simple, and just pull S-Video right off the huc6260

the cap is 0.001uf
the transistor i tested with is an S9013
40 is pin 40 of the huc6260
comp is anywhere you can get composite video (I tapped the vid pin on the RF modulator)

 Yeah, but C(chroma) line isn't clean. Some svideo input displays *might* have a problem with it (one TV I had was quite touchy about svideo spec. It wouldn't see chroma for SNES Y/C. It came out B/W). Why not just tap pins 20, 26, 33 directly and build the amp circuit for that, for C?  

lastcallhall: If I give you an ISO, can you burnt it and test/capture the screen for me?

[thesteve]

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

[lastcallhall]

 Yeah, but C(chroma) line isn't clean. Some svideo input displays *might* have a problem with it (one TV I had was quite touchy about svideo spec. It wouldn't see chroma for SNES Y/C. It came out B/W). Why not just tap pins 20, 26, 33 directly and build the amp circuit for that, for C?  

lastcallhall: If I give you an ISO, can you burnt it and test/capture the screen for me?

This isn't for my Duo-R, this is for my TG-16. My Duo-R doesn't read burnt discs anyway...

EDIT: Is there somewhere I can see the C6260 pin values?

[Bonknuts]

 Yeah, but C(chroma) line isn't clean. Some svideo input displays *might* have a problem with it (one TV I had was quite touchy about svideo spec. It wouldn't see chroma for SNES Y/C. It came out B/W). Why not just tap pins 20, 26, 33 directly and build the amp circuit for that, for C?  

lastcallhall: If I give you an ISO, can you burnt it and test/capture the screen for me?

This isn't for my Duo-R, this is for my TG-16. My Duo-R doesn't read burnt discs anyway...

EDIT: Is there somewhere I can see the C6260 pin values?

http://i1216.photobucket.com/albums/dd379/PCGenjin/cvbs.png?t=1295176022 (the resistor values are somewhat off because I measured them in circuit - yeah, yeah ) Your Chroma line has both Y and CB on it, when it should only be R-Y and B-Y. Some svideo receivers will probably just remove *everything* with a notch filter. Remember, Chroma is still a 3.58mhz signal - or rather it's supposed to be. Some TVs and NTSC input devices might share common lines/inputs and it could through off detection logic. I know my capture card has a separate plug for svideo, but if there is CB on the Y line on the input - then it just treats the whole thing as Composite and ignores Chroma line decoding (and vice versa. Remove CB, it removes the filter circuit for Y which gives a much sharper image - allowing you to see the chroma dot pattern interference on Y). Your setup doesn't have CB on Y, but that doesn't mean it won't throw off other redundant checks on the svideo input of the device (and either disable it or give weird results).

[nat]

This is a great thread.

In the past, I built an encoder based on (I think) grahf's design for SVIDEO output mods and it seemed to work OK.

I'm going to have to give steve's more direct approach a shot and see where it gets me. It seems.... Too easy.

[Bonknuts]

Hmm, looks like I was wrong. I mean, you need CB on Chroma line besides the other two - just not Y. Was just looking through old notes: http://forum.fobby.net/index.php?t=msg&goto=941& (also, the real values for the resistors are there)

[thesteve]

the way i did it the Y is clean (I checked) as 3.5Mhz is higher than your clock i was able to greatly reduce its Y content through a simple capacitor.
using 2 op-amps to invert and amplify the C and just buffer the Y would provide a better signal.

[lastcallhall]

Some comparison photos. S-video is on the left, composite (pulled from A23) is on the right:













(This one I may have picked a different court between the two)

[ApolloBoy]

Looks pretty good, do you have higher res screencaps?

[lastcallhall]

Photobucket resized the images, and they're too big to upload on here. If you know of a working file hosting site I'll up them there.

EDIT: Here you go:

File name: Comparison.zip File size: 1.65 MB