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

[TurboXray]

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?

[TurboXray]

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?

(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.

[TurboXray]

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

[ApolloBoy]

Wow, that's quite the difference! I'll have to start offering this mod now, what value resistor did you use?

[lastcallhall]

100 Ohm. I may tinker with that value a bit, maybe a 220 or a 330 and see what the difference is.

[roflmao]

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

Looks amazing!

[Keith Courage]

It would be awesome if you could write out what pins you used and parts etc... for the community here that others would know how to do the upgrade.

[thesteve]

all the info is in a post above. (post 34)
thats how LastCallHall was able to do it

[lastcallhall]

all the info is in a post above. (post 34)
thats how LastCallHall was able to do it

What he said.

Really, credit for this goes to thesteve, as he was the one who provided the info; I just had the system to use as a guinea pig.

Also, @thesteve: if you look at the comparison photos, especially the download package I linked to, you can see some noise when using composite. I just ran the composite signal straight from the EXP port; do you think if I placed a cap in series with the signal it would clean that up?

[thesteve]

i had a TG16 on the bench for region mod so i tested some signals and built it.
the reason i was thinking on the subject was this thread.
i just installed it in my DUO and used a 75ohm resistor.

[thesteve]

one of the high res pics
S-Video Left v. Composite Right

[SignOfZeta]

These look to be taken from a capture card. Is all that jpeg compression noise coming from there, or can you reduce that somehow?

[SignOfZeta]

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)

Wait...that's it?

[thesteve]

thats it 3 parts

[SignOfZeta]

So the Hu6220 outputs a luma signal, but not a desecrate chroma signal. Is this common? I assume I would get better results with a RGB to s-video encoder like a NeoBitz (if I could actually get the fucker to work, which I'm sure I couldn't)?

Anyway, I guess I'll try this soon.

[thesteve]

the chroma signal is there too it just requires another amp (inverting) from pin 20.
the best way is to use a high speed op-amp 2 channel for luma and chroma

[thesteve]

the neobits is less than perfect too, due to the sync offset.
the 6260 sync is delayed for final mix, causing it to not properly align with the RGB signals

[TurboXray]

So the Hu6220 outputs a luma signal, but not a desecrate chroma signal. Is this common?

Didn't see the links I posted earlier? Here and here. Not only does it output a clean chroma signal, it actually outputs both separate color components. The final step of the quadrature amplitude modulation to make C is done in the analog circuit (two lines are tied together). All VCE chip models for the PCE console systems have this (there are two revisions). I've never taken apart the portable PCEs, but I've been told they use the same VCE (huc6260) chips as well.

 It outputs 4 lines: Y + sync, Color burst (the reference signal for chroma), R-Y and B-Y.

I assume I would get better results with a RGB to s-video encoder like a NeoBitz (if I could actually get the fucker to work, which I'm sure I couldn't)?

This method gets you the same custom/unique color space that the PCE always had, just nice and clean. RGB out on the PCE has a different color space. If you care about real PCE colors, this would be the way to go IMO.

[thesteve]

thats an odd configuration, as the Cb,Cr is interleaved in the chip (even if mixed externally)
all 4 signals come out inverted and are fed in to an inverting amp and then a buffer/driver

[TurboXray]

Now all you need to do is separate Y from sync on the Y+sync line, scale Y down my 92.5% then shift it back up into place (IRE 7.5). Then you'd have true brightness scaling that the Japanese experienced with their NTSC TVs and Japanese consoles. 

 They didn't bother fixing the IRE 0 vs IRE 7.5 issue when they brought out the TG16 and Duo. What does it mean? Makes the brightness of the all the colors closer together, rather than spaced apart. They blend a little better in relation to each other. Of course, that would be over the top or best of the best mod setups. Doubt people are really that ana.. err picky.

[lastcallhall]

These look to be taken from a capture card. Is all that jpeg compression noise coming from there, or can you reduce that somehow?

They are indeed taken from a capture card. But notice the noise on the composite side over the s-video - that makes me think you can clean the composite signal up a bit. I'm out of parts for this stuff ATM, so I'll be submitting an order to digikey shortly to get everything I need to test this out a bit more.

RE: Cleaning and inverting pure Y/C - That would still be a relatively small circuit to construct, no? I wonder how much better the signal would look, and if it's worth it.

[thesteve]

it would depend on the monitor
on some you will get a color mark on hard lum transitions white to black black to white ect, others wont see it at all.
the simplest way is a 2 channel video op amp

[Keith Courage]

Awesome info, I will be trying this out myself at some point once I buy the needed materials.

[thesteve]

if you have any scrap boards around you have the parts

my next task is composite from the express (without an encoder)
I have lum now

[Keith Courage]

Pardon me for being stupid but I don't quite understand the diagram. What is pin 40 and what does it do? Which pins on the transistor get wired up and where to? Also, what is the part marked with a 100 coming off of the transistor?

[ApolloBoy]

Pardon me for being stupid but I don't quite understand the diagram. What is pin 40 and what does it do? Which pins on the resistor get wired up and where to? Also, what is the part marked with a 100 coming off of the transistor?

Pin 40 is luma (brightness) on the HuC6260 chip. On the transistor (not a resistor), assuming it's a standard 2N3904, you wire up the middle pin (base) to pin 40 on the HuC6260, the left pin (emitter) goes to a 100 ohm resistor and then to the luma pin on your S-video jack, and the right pin (collector) goes to 5V, which can be found on the HuCard slot or various other places on the board.

For chroma (color), take the composite video signal, wire it up to a 0.001 uF ceramic cap, and the other end goes to the chroma pin on the S-video jack.

[Keith Courage]

Thank you very much. That makes a lot more sense. I was looking around the internet trying to figure out what the hell pin 40 did. So does this mean no video amplification of any kind will be needed for this to work or does it still output a week signal?

[thesteve]

the transistor is your video amp for pin 40
your taping chroma from amplified composite, so no amp needed

[Keith Courage]

Quite the badass setup. Thanks for the help. I'll get around to doing this on my duo-r in the next couple days I hope.

[Keith Courage]

So both the composite sync and pin 47 from the RGB go to the same pin on the S-video jack? Maybe I am just confused as to where the RGB signals go?

[SignOfZeta]

You aren't using the RGB signals.

[Keith Courage]

Ha yeah, I just figured that out. I just spoke with the steve. I was looking at the completely wrong diagram online.


https://jrok.com/hardware/RGB_diagrams/video_output_wiring_v31.jpg

I got it all wired up nicely now. Even made a nice mounting place for it on my DUO-r. Thanks again steve.

[lastcallhall]

Ha yeah, I just figured that out. I just spoke with the steve. I was looking at the completely wrong diagram online. http://jrok.com/hardware/RGB_diagrams/video_output_wiring_v31.jpg

I got it all wired up nicely now. Even made a nice mounting place for it on my DUO-r. Thanks again steve.

Where did you put yours? I've been looking over my Duo-R and can't decide on a location.

[Keith Courage]

I mounted it directly next to the din5 port on the rear. I am not at home right now to be able to take a pic but here is an older pic of my system. RED is where I mounted the S-video jack. It makes it real easy having it there cause you can tap composite and the 5V right from the Din 5 port. I actually mounted mine right to the plastic with some glue and one screw for the hole in my s-video jack. I didn't actually solder it to the board. However, in the future I might consider soldering the grounds to the board since that spot on the board has a large area of ground to scrape free. It's almost like the system was setup for that spot to take an S-video jack in the first place cause it is the perfect size.  Alternatively you could use a Din 8 connector instead of a din 5(standard DUOs already have them) and wire it up to the other non used pins much like an RGB mod. Then make yourself a Din 8 AV cable with S-Video and AV on it. This method would take much more time not to mention the need for always having to have your specially made AV cable to use it.

/cimg6384stuff.jpg

[thesteve]

there's mine

right next to my RGsB

[lastcallhall]

Awesome, thanks for the suggestions!

[Keith Courage]

The S-video I have looked good but was way to bright compared to the original composite. Meaning the colors don't look as good in my opinion being so bright. Since I had already bought myself a 5 pack of resistors I wired up a 2nd 100ohm resistor in series with the first one and it fixed it. The video looks awesome now. So I suppose if anyone else is thinking about doing this you might want to consider using a 200ohm resister instead of 75 or 100. Oh and here are some updated pics of where I mounted it. Because of where I mounted the jack I had to break off one mounting pole from the case lid. The mounted pole isn't an important one since no screws go inside of it and nothing goes around it. So if you don't have an 8pdt switch in your system then it might be better to put the S-video jack on the other side so you won't have to do any case modifying.

/cimg6508m.jpg
/cimg6509o.jpg

[thesteve]

as i said your resistance will vary depending on the transistor used

[lastcallhall]

as i said your resistance will vary depending on the transistor used

Yep, I had also wanted to test the signal with 220 or 330 ohms to see the difference. Thanks to Keith Courage for testing out the 200 ohm range. Still, I may get a variable resistor to play with the color a bit without having to destroy the circuit every time.

[Keith Courage]

I was wondering if anyone else has experienced this and if maybe there is a solution. On some TVs I notices wavy lines going across the screen with my S-video. It looks like what happens when you have ground interference. Could I maybe have a bad ground inside the system? I tapped my ground right off of the bottom metal plate. Is it maybe a bad s-video cable?

[ApolloBoy]

I was wondering if anyone else has experienced this and if maybe there is a solution. On some TVs I notices wavy lines going across the screen with my S-video. It looks like what happens when you have ground interference. Could I maybe have a bad ground inside the system? I tapped my ground right off of the bottom metal plate. Is it maybe a bad s-video cable? 

Try moving your ground to a ground point on the motherboard itself and if that doesn't work, try a different cable.

[thesteve]

you need to tap your ground from the board, not the plate.
you could have a bad cable as well, but because this method uses a current controlled sig, not voltage controlled it should be less suseptable to cable issues causing noise (open cable= no pic)

[Keith Courage]

Well, I soldered the ground to the board itself and the issue got better but was still slightly noticeable. The rest of the problem got cleared up when I moved my S-video cable away from the other cables that sit behind my TV. My cable must have been getting interference from something back there. Thanks guys