Easy SNES/SFC YUV component video!

[segasonicfan]

this is all very exciting!

Component can be a pain, and the green always needs tweaking. But for those of you with 100+ chips, I definitely want to buy a couple off ya to give this mod a go.

also, while its not ideal, you can easily make video brighter just using some video amps. Theres some IC ones out now that integrate the transistors and such and work very well.

[promking]

Would anyone be willing to do this Mod for cash?

[burn654]

Just wanted to come back here to thank you Ace for your great schematic, I rebuilt my circuit (for a standalone converter box) using a fresh ba6592f with an ebay sop-to-dip adapter and it worked great with my Genesis model 2, it looks fantastic!!

That said - I still have major sync issues from my Dreamcast rgb scart cable. I checked my cable and it's wired for composite sync and has pin 7 grounded (15khz mode). I get good color but I just can't dial in my sync. The only thing that seemed to work was dialing down my luminance really really low (to the point of getting a really dark picture) or doing something similar with an external sync mix, throwing a trimpot on to mix that into luminance.

Could the sync polarity be a problem? I've heard varying reports that Dreamcast has positive sync...Genesis uses a negative sync...if that's the case I would hope a sync inverter chip would fix my issue.

Has anyone tried this circuit with a Dreamcast in 15khz (480i/240p, RGB) mode?

[Ace]

Interesting that you make mention of this. While I won't be able to test on the BA6592F as I've ditched this encoder for the BA7230LS, I think the issue would still present itself on the BA7230LS. I have a Dreamcast SCART cable which I will have to adapt to the DB9 plug on my box, so once I get that working, I will check if the video fails to sync.

Which reminds me: what kind of Composite Sync do the Saturn and Master System output and what kind of Composite Sync do you get from an LM1881 which is used to get Composite Sync from Composite video? If it's all negative sync, there's a high chance sync polarity may be an issue with the Dreamcast.

[burn654]

Thanks Ace, I'll be interested in your results!

what kind of Composite Sync do you get from an LM1881 which is used to get Composite Sync from Composite video? If it's all negative sync, there's a high chance sync polarity may be an issue with the Dreamcast.

From what I understand it should be a negative sync. I've actually built an LM1881 sync stripper with a toggle switch in my BA6592F box for the instances that *might* need it but it doesn't seem to help on Dreamcast for me. (which should be putting out composite sync anyway).

At least for me, things like the bootup screen will be relatively stable, then the main menu freaks out. Adding some resistance to luma or the sync line (I forget which, I reverted my crazy changes) can fix it but then games will still be messed up unless I put way too much resistance on the line. (Causing the aforementioned dim picture) Lately I've been using the chip's sync but had similar findings mixing the sync into luma separately.

Basically the problems I had prior with this circuit I've deduced to being Dreamcast related, it really does look stellar for me on Genesis. It's actually hard to *make* it go out of sync.

My TV is a 36 in. SD Trinitron by the way.

[burn654]

Just a friendly bump.

I've tried the Dreamcast 240p Test Suite and noted that I get the same out of sync picture with both 480i and 240p settings from the console. However, the Dreamcast startup screen and Sega disc-boot logos are in sync. Very strange. My cable has 220uf capacitors on the rgb lines, previously it had 100uf's and exhibited the same behavior.

Guess I'll look at ordering a sync inverter chip, or another scart cable. Mine is third party but I think the wiring is correct.

[scarmullet]

Alright, I want to do the SNES Component Mod, and my SNES has the S-ENC chip, and in reading the thread, all I have to wire up the jacks. May I ask which pins go to the Y Pr and Pb jacks?

I have an idea, Pin 23 Is Y, so that would be Green. Pin 1 goes to the Pr jack, and 24 goes to the Pb jack, at least according to this

http://console5.com/wiki/BA6592F

[Ace]

This is a bit late, but...

Just a friendly bump.

I've tried the Dreamcast 240p Test Suite and noted that I get the same out of sync picture with both 480i and 240p settings from the console. However, the Dreamcast startup screen and Sega disc-boot logos are in sync. Very strange. My cable has 220uf capacitors on the rgb lines, previously it had 100uf's and exhibited the same behavior.

Guess I'll look at ordering a sync inverter chip, or another scart cable. Mine is third party but I think the wiring is correct.

A 3rd-party SCART cable makes me think the cable is wired for Composite video on the Sync pin rather than Composite Sync. Try to use an LM1881 on that cable and see if it changes anything. Or if you have access to an official Sega SCART cable, try that as it's wired for Composite Sync instead of Composite video on the Sync pin.

Alright, I want to do the SNES Component Mod, and my SNES has the S-ENC chip, and in reading the thread, all I have to wire up the jacks. May I ask which pins go to the Y Pr and Pb jacks?

I have an idea, Pin 23 Is Y, so that would be Green. Pin 1 goes to the Pr jack, and 24 goes to the Pb jack, at least according to this

http://console5.com/wiki/BA6592F

You got it right. Just make sure that if you take the Luminance (Y) straight from the S-ENC, you add a 75ohm resistor between the encoder and your green RCA plug, otherwise, the video signal will be too bright.

[scarmullet]

This is a bit late, but...



A 3rd-party SCART cable makes me think the cable is wired for Composite video on the Sync pin rather than Composite Sync. Try to use an LM1881 on that cable and see if it changes anything. Or if you have access to an official Sega SCART cable, try that as it's wired for Composite Sync instead of Composite video on the Sync pin.



You got it right. Just make sure that if you take the Luminance (Y) straight from the S-ENC, you add a 75ohm resistor between the encoder and your green RCA plug, otherwise, the video signal will be too bright.

Thanks man, as soon as I get my SNES out, I'll pull component out right away.

[scarmullet]

I did the mod, and I am having issues. Using the BA6592F SNES and ACES diagram, I wired up component jacks and it works...only with the SNES top is off. When it is on, I get nothing. No picture or no sound.

Also since I did the mod, I have not been able to get composite video out of the system.

[Lastcallhall]

You're grounding something out. Make sure the heat shield isn't cutting into any wires or grounding out the signal altogether. I'd start with the top off and check continuity for everything.

[scarmullet]

To be sure, I wrapped the board I made in Electrical tape to prevent such occurances...its still doing it.

[burn654]

A-ha Ace, that must have been the problem!

I was building a PC Engine Duo rgb mod and my converter box didn't like the Composite Sync from it. So on a whim I built another LM1881 separator for it using the Composite video. It then synched no problem. The separator in my box was wired incorrectly!

So basically I fixed my LM1881 switch circuit on the BA6592F box, with the LM1881 enabled the Dreamcast syncs fine. Thus the cable was wired for Composite Video.

So that's two more consoles that are working with it!. Thanks Ace