PC Engine / Turbografx16 s-video mod

[Drakon]

Video signals come from the huc6260 chip

Revised circuit:

/pcenginesvideoandstereo2.jpg
/pcenginesvideoschematic2.jpg
/newpcengineports.jpg
/badasspcengine.jpg

New demo capture:

[Keith Courage]

We already have a write up on this here https://www.pcengine-fx.com/forums/index.php?topic=10850.105. Your method is a bit different than the method that some of us here have been using. I wonder if there is a quality difference between the two?

[Drakon]

Yeah I never found yours so when my pc engine showed up I just made my own.  Well the beauty of my circuit is the only parts needed are some wires and a s-video jack.  I just removed 1 resistor and straight wired and the picture looks perfect  

You certainly don't need a transistor to amp the luma once you disconnect that resistor.  The luma looks perfect straight from the chip when it's connected to nothing else.

[Keith Courage]

Ah I see, so in doing so the RF jack no longer works? Does the composite out of the rear pin out still work?

[thesteve]

no composite and RF are disabled by this mod
further the 6260 chip is overloaded






edited to correct chip number

[Drakon]

no composite and RF are disabled by this mod
further the 6280 chip is overloaded

Overloaded in what way?  It works fine wired like this.

[thesteve]

the supply is drawn down as the 6260 was not designed to drive loads.
also the output from the chip has a significant voltage offset.
i am not denying that it worked for you, just it will depend greatly on the monitor.
as to the overload i cant say if the chip will fail from it or not.

[Drakon]

well I wired in a single transistor amp / buffer and it was too bright.  So I straight wired it and the brightness is perfect.  I cleared all of street fighter 2 yesterday and no issues.

pictures:

/pcenginesvideo.jpg

[thesteve]

use the transistor amp/buffer to protect the chip and add a resistor to bring down the brightness

[Drakon]

use the transistor amp/buffer to protect the chip and add a resistor to bring down the brightness

For the sake of science I'll leave my system wired up the way it is and if it ever stops functioning or blows up I'll be sure to let people know about it.

[Drakon]

Whoa you guys were totally right!  The picture looks much better with the 1 transistor amp and then a resistor.  Thanks a lot for correcting that.

[thesteve]

not a problem

[Duo_R]

Wow awesome job here! That's crazy that it is that simple

[Duo_R]

Also I am wondering if one of those S-video to composite adapters would give a good picture for composite video....

[thesteve]

should

[Drakon]

Revised circuit:

/pcenginesvideoandstereo2.jpg
/pcenginesvideoschematic2.jpg
/newpcengineports.jpg
/badasspcengine.jpg

New demo capture:

[Drakon]

Question, since I disconnected luma from the composite video circuit is it still necessary to use a capacitor to "filter out" the chroma signal?

[thesteve]

no its not

[Bernie]

Damn.   I want this done now.

[Drakon]

Damn.   I want this done now.

It's really easy and the results are nothing but perfection.  You can hire myself or thesteve if he's up to it.  I'm posting this on a few places so it's more known.  I honestly didn't even know the mod even existed until after I followed some schematic of the video circuit and wired up something myself.

[Bernie]

Ill get with one of yall soon.

[SNKNostalgia]

Anybody know how the picture differs from an external S-video mod from D-Lite or grahf's improved version?

[Duo_R]

Those mods use a video encoder chip CXA1645 to convert RGB TO Svideo. This diagram uses existing signals and builds it to useable Svideo signal. This method if proven stable is a cheaper solution.

Also is RGB still useable after this mod?

[thesteve]

yes, RGB will not be changed by this

[SNKNostalgia]

Yep, I know about the board having an RGB amp then converted to S-Video with a CXA1645 or a CXA2075 in my case 

Is the S-video picture quality the same is what I am wondering?

[thesteve]

the quality may be the same, but the color space is different
this way preserves the PCE tuned color space, whereas RGB to S-Vid skips the tuning

[Duo_R]

ah sorry man misread what you wrote there. Yeah it would be nice to see a side by side comparison.

Yep, I know about the board having an RGB amp then converted to S-Video with a CXA1645 or a CXA2075 in my case 

Is the S-video picture quality the same is what I am wondering?

[Drakon]

The s-video generated by the console is absolutely beautiful I can pretty much gaurantee it looks better than externally encoding the rgb into s-video.

[SNKNostalgia]

I find it funny how it took till now to just simply tap S-Video out of the system with just 2 parts. All these damn years, lol.

I remember saving up for region/S-video on my practically new US Duo and finally finding someone to do it (grahf) back in 2006. Glad I got 2 nice clean modded boards in there. Looks like manufactured quality parts instead of homemade pcb setups.

[Drakon]

Having the circuit diagram of the video signals made this mod super easy so we should thank whoever bothered figuring it out.

[Duo_R]

Yeah that's pretty crazy, also not that long ago it was discovered some SNES units have built in component video, just needs to be wired to the jacks.

I find it funny how it took till now to just simply tap S-Video out of the system with just 2 parts. All these damn years, lol.

I remember saving up for region/S-video on my practically new US Duo and finally finding someone to do it (grahf) back in 2006. Glad I got 2 nice clean modded boards in there. Looks like manufactured quality parts instead of homemade pcb setups.

[NightWolve]

Yeah that's pretty crazy, also not that long ago it was discovered some SNES units have built in component video, just needs to be wired to the jacks.

You sir, are awesome! Your mentioning of built-in component video peaked my interest which led me to search around for info about it, and in a couple of hours I was able to implement it on my SNES! It works wonderfully on my 32" CRT in my entertainment room, but I tried it on my modern 22" 720p HDMI flat panel (my computer's monitor) and it doesn't there. I know from thesteve and others that newer TVs demand a 480p YPbPr Component signal or they will reject it, so one would need a resolution doubler to make it work in that case. Anyhow, seeing it perform on my CRT was truly a blast. I tried Chrono Trigger, Super Bonk, F-Zero, Donkey Kong 3 and was quite amazed at the difference! I did have to turn the color level up, though. The S-Video output is very Chroma heavy compared to it, so that was one difference, but aside from that the component signal is mostly ready-to-go just by tapping the proper contact points (I think technically, as some experts are saying, the Blue and Red signals probably do need to be amped a bit, that or turning up the color level). I followed these:

http://www.nintendoage.com/forum/messageview.cfm?catid=22&threadid=71069



Tapping the luma (Y) from the Multi-AV out (which is used for s-video) is the better point instead of the chip. Now I just need to buy a Component RCA mount to install on the case and solder the wiring for good. But anyway, yeah, as it is a 240p signal, it might not work in newer TV sets without a resolution doubler...

Oh yes, fair warning, I thought I broke my SNES at first. After you solder the wires to the board, you'll really need to put it back together for testing - the sound module has to make contact with the heat sink mold and what not. I tried to quickly test before putting it all back together but no game would load and I wound up burning out the fuse near the power switch fucking around that way, so I had to solder a bypass wire unfortunately. Not good, but oh well. Also, newer revisions of the SNES board do not support Component - you can only do this if you got an early model with the S-ENC chip (mine is 1990) or that one in the image!

[SNKNostalgia]

Yeah that's pretty crazy, also not that long ago it was discovered some SNES units have built in component video, just needs to be wired to the jacks.

I find it funny how it took till now to just simply tap S-Video out of the system with just 2 parts. All these damn years, lol.

I remember saving up for region/S-video on my practically new US Duo and finally finding someone to do it (grahf) back in 2006. Glad I got 2 nice clean modded boards in there. Looks like manufactured quality parts instead of homemade pcb setups.

Now, that just blew my mind. I thought there was some complicated mathmatical difference using a certain chip between red and blue to get component. It is setup to just work like that? Man.....

[NightWolve]

Now, that just blew my mind. I thought there was some complicated mathmatical difference using a certain chip between red and blue to get component. It is setup to just work like that? Man.....

If your SNES model has the S-ENC chip like you see in the first image, then yeah (Mine looks different because it's a 1990 early release model, just says S-ENC on it, no 'BA65942AF' and it's in a different location, very close to the Multi-AV out). The story is that they found the datasheet on that video encoder chip which shows you on page 6 that pin 24 is Blue-Y and pin 1 is Red-Y and Luma (Y) is the same Luma that was being outputted for the S-Video which SNES always had (though I hear some newer models were fucked up and don't have it) hence you can tap it from the Multi-AV out. But yeah, newer revisions of the SNES removed this S-ENC apparently in favor of a S-RGB chip, so only raw RGB would be present in that case, thus you'd need the usual RGB->Component encoder... You still have the 240p problem not working with newer TVs of course.

Anyway, it's pretty cool, but it probably does need some amping. The color level has to be turned up, but other than that, it works beautifully on my 32" CRT. Compared to S-Video, (I would switch from s-video back to component during the testing) the message boxes had clear color, no fuzzy drawn sprites when there was movement, clearer drawn text, etc. Some fine tuning IS needed, but yeah, it might work well enough raw (as it does for me) with just soldering wires from the board to RCA jacks. I still have to research the fine tuning which I might as well do.

Screenshots from the guy whose mod images I used:

42" Plasma


35 inch CRT


So that's just tapping the signals raw like I just did today, no amps or anything. Color level of TV has to be turned up, maybe tint adjust too (according to him). That plasma looks beautiful!

[thesteve]

those outputs do need a buffer amp.
a simple transistor amp will do

[NightWolve]

Can you provide any more specific details, steve, that would like, you know, actually be helpful such as which transistor to buy and wiring methods, etc.? Some are saying resistors are needed too. Pretend you're talking to someone that doesn't have ANY of your engineering background. ;) I wanna put an order in for female RCA jacks so in wanting to do it properly, I can buy the stuff from the same place (assuming digikey/mouser will have all that I need).

[thesteve]

well it depends slightly on the voltage offsets from the chip.
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CFIQFjAA&url=http%3A%2F%2Fmikejmoffitt.com%2FBA6592F.pdf&ei=6t8VUIDwCsS7qQHX-oDgCA&usg=AFQjCNGPG_XtoF_qZjhQ51G-9SHRtY7K3A&sig2=ax-tHwA3ImKeka2beQwFuw
using the circuit they used for the composite output should work

[NightWolve]

Hm, it seems there is a lot of confusion but I think understand better. One guy is reporting that if you have an actual BA6592F chip, you need the amps. I have the S-ENC chip with only 4 useless numbers on it, which, since it worked right away without anything, means I don't need the amps in my case (duh, other guys were reporting dark colors, mine worked pretty great)! Oh, and in the images I posted above, that chip is a S-ENC BA6594AF, slightly different number and it's working for the guy, which means it is already amplifying the signals for near proper usage strength, etc. Many board revisions and changes here, so that is the deal.

But, there was talk of needing 1k Ohm "pull-down" resistors. What do you make of this image ?



I think that might be more applicable in my case, though I dunno what the heck they're wanting to do to the luma signal. I am betting that if I tap the luma from the chip, it's going to work fine. Think I'm gonna do that now actually. But as you can see, it suggests a 1K Ohm resistor to ground for R-Y (Output) and B-Y (Output) pins. Moreover, with the Y/Luma (Output), pin 23, it wants a complex circuit using the luma input signal that enters the chip from pin 9! Why are they wanting that done, what difference would it cause and really, isn't the S-Video Luma the same as what an analog component signal uses? I kinda suspect it'd be more proper to do it like that and that maybe it'd make the whole component signal more compatible, aside from the 240p issue.

So, what I think is the deal is, technically, seems like the the Component video signal is supposed to be nearly ready for use by default without amps, no? I got a great picture (though a little low colorwise), and it seems those that found they had to use amps were just getting a dark one with another type of chip, though similar, etc. I dunno... whatever, it works pretty good in my case without anything and it's been somewhat interesting modernizing my good ole SNES, so not entirely a waste of time!

EDIT: Yeah, here's what he said (Ace): "I don't get it: it works on the S-ENC, but it doesn't work correctly on the actual BA6592F  ......  I was right. You need an amp for the real BA6592F. With no amp on the B-Y and R-Y outputs, you won't get any color. You also shouldn't take Luminance straight from the encoder, but rather pin 7 of the multi-A/V out as it too needs an amp which is already present on the motherboard."

[thesteve]

the 1K is the proper load for the chip
the transistor and resistors shown provides the 1K load to the chip, and keeps the 75Ohm load off it.
copy it for the other lines for better color

[NightWolve]

The modding continues. Instead of buying female RCA jacks, I used a triple Component RCA mount from a DVD player that broke. Using a wood-boring drill bit, the SNES plastic was easy to handle. It worked out nicely:



My 1990 first generation SNES PCB board near the 9239 S-ENC chip:

[Duo_R]

nice job Nightwolve, I have a jack exactly like that from an old broken DVD player. That turned out pretty nice!

[Duo_R]

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.

[Drakon]

no clue what cg means.  If the cd rom unit has you get video from where you get video without the cd rom then yes it should work fine with this mod.

[Duo_R]

CoreGrafx - it is like what you have except it has a 5 din plug instead of RF only like your White PC Engine.

[SNKNostalgia]

My SNES say S-RGB and BA6592F under that. So does that mean it still has component video with the same number?

If not, then what a shame. It doesn't have the known faded vertical bar in the middle of the screen like most SNES consoles.

[NightWolve]

Yeah, that chip outputs it - you have an early SNES unit, it's just newer than mine! You can do it!

sega-16.com/forum/?20732-Easy-SNES-SFC-YUV-component-video!

Even if you just google BA6592F, the first search result shows you an image of the chip with the first pins 1 and 24 corresponding to Red-Y and Blue-Y. And Luma/Y should be tapped from the Multi-AV out since it's properly amplified for usage given the s-video support.

https://console5.com/wiki/BA6592F

[Drakon]

*bump* added some new s-video demo action on youtube.  Here's my machine now:

/drakonpceod.jpg

Here's a capture with s-video and stereo sound:

[NightWolve]

Looks good!

[EvilmaxWar]

Thanks for this mod Drakon, and others who helped too of course! I just did this mod on my US TG16, worked flawlessly. The picture is AWESOME, it even fixes that horrible shimmering that is always there on composite when scrolling. Hyperdyne Sidearms looked like shit now it looks as sharp as on an emulator!

I figured the solder points with the schematic. I still need to hook up audio and fine tune the resistor value for optimal brightness.

Once im done ill make a diagram with a picture of the US motherboard, maybe it will help people wanting to mod their US TG16.

[NightWolve]

The picture is AWESOME, it even fixes that horrible shimmering that is always there on composite when scrolling. Hyperdyne Sidearms looked like shit now it looks as sharp as on an emulator!

Hm, that's kind of a good way to describe it, a "shimmering" effect when scrolling. I was actually trying to find a better way myself besides referring to it as dot crawl, which I think is mostly what's responsible for that (100% when it's a composite signal), but even with a S-video test on my Turbo Duo and my SNES, while it was greatly reduced, there was still some of this shimmering left. In the case of my SNES, after the component video mod was put into place, THEN it was beautiful, frankly, and that effect was practically eliminated! Clear coloring, no interference artifacts, good sharpness, contrast, scrolling, etc.