Easy SNES/SFC YUV component video!

[Ace]

I just tried this on my Neo Geo... it didn't work at all. The video is stable or a second or two, then starts to scroll like it's losing its sync signal. I'm going to take the circuit out and plant it into a virgin VA3 tomorrow to see if there's any difference, but for now, I'm heartbroken.

Sounds like what happened with my faulty BA6592F. It worked for a few minutes before the video went completely out of sync and the blue progressively got weaker. The faulty chip would actually work correctly if I bypassed the amp on the Luminance or if I directly put the sync on the Luminance output, in which case, anything gray or white would show up black (a clear sign there's no luminance being output from the transistor at all). This would, however, make the picture much darker and more saturated, so you would need to put stronger resistors at the red and blue outputs after they're amplified.

I must also ask: where are you taking the RGB from? The video encoder's RGB inputs or outputs? Remember this: you must use clamped RGB for my circuit to work correctly.

[Lastcallhall]

RGB out. I'm half tempted to desolder the av out jack and wire it from there. Provided the circuit works on the Genesis, that is.

[Ace]

The circuit works no problem on my VA3 Genesis Model 1 I modified for a second RGB output from the EXT port minus the aforementioned video problems (most likely caused by either a bad cable or a damaged trace on the Genesis' PCB). I'm gonna ask Apolloboy to ship me some U-shaped 8-pin DINs so I can test my RGB to Component box on an unmodified Genesis.

Tip: NEVER bend the pins on the BA6592F. It seems very sensitive to bent pins, and I think this is what caused the blue to fail on the first BA6592F I used in my RGB to Component box and what caused the red to fail on the second BA6592F I desoldered off of a dead Super NES. As soon as I swapped encoder on my RGB to Component box, the sync issues disappeared and the blue was perfect. So long as I don't plug in my EXT-port-turned-RGB-output-modded VA3 Genesis Model 1, the box works perfectly, and let me tell you something else: be sure to glue down the encoder then solder directly to the pins. Don't use a surface-mount to DIP board; I always got crap out of these.

[Lastcallhall]

Yeah I glued the ic straight to the board and worked from there, although I may have damaged something in the process... I'm currently on the couch recovering from a possible heat overexposure, but I have some time off so I can get to it soon and see what happened. Good thing about glue is I can pop the ic off and put another in its place easily.

[Lastcallhall]

So, thanks to Ace, I finally got this working on my Genesis, with the Neo Geo to follow shortly.

In short, this thing looks great. I was a bit concerned about the color temps on my test TV, but once I hooked it to my RPTV, all my fears subsided - it looks emulator perfect. The same can actually be said for my 40" HDTV - it can apparently take a 240p signal. The best thing about that is, is there is no lag time in button and d-pad responses. You can see the overscan, but that's not a dealbreaker. Although, my HDTV seems to be picky about it's L/R sound channel seperation - the left is really muffled. I'm going to connect my Sega CD and see if that remedies the issue, and if so, a cap replacement is in order. Although, for now, I'm glad it works!

+1 to Ace, since I can't rep him any more at the moment.

[Guntz]

Can you share with the rest of us what the eventual fix was?

[villahed94]

Well, I'll try and make it as soon as I get the chips, and as soon as my Va2 revives.

[Lastcallhall]

Can you share with the rest of us what the eventual fix was?

The sync issue I cleared up by using a 2N3904 transistor instead of a 2SC945, but I suspect there was a bad solder joint somewhere along the sync line.

I also had B-Y and R-Y reversed, so that was easily fixed. I've created a PCB using Pad2Pad using Ace's design; we've talked about a batch order, but we'd need at least 100 for the order to be cost effective.

[Chilly Willy]

The sync issue I cleared up by using a 2N3904 transistor instead of a 2SC945, but I suspect there was a bad solder joint somewhere along the sync line.

I also had B-Y and R-Y reversed, so that was easily fixed. I've created a PCB using Pad2Pad using Ace's design; we've talked about a batch order, but we'd need at least 100 for the order to be cost effective.

Well, figure out what they'd cost and we can start a group purchase thread... I'd probably go in for a few myself.

[Lastcallhall]

You're looking at 2.75 per board if we do 100, but Ace has final say in this since it's his circuit.

[Chilly Willy]

You're looking at 2.75 per board if we do 100, but Ace has final say in this since it's his circuit.

Yes, but then there's the parts and labor and shipping... and most folks probably aren't opposed to trying to make a LITTLE profit on it. What people hate are when people take a product and charge 10X the cost for it.

[Lastcallhall]

Oh, yeah, I totally see your point. That cost is just for the board and shipping - depending on where you get the other parts, you're looking at around another 5-6 bucks plus shipping on top of that if you buy in bulk. I had been wondering how to get 100 boards ordered, and a group buy seems like the best way - I just dont want to overstep my bounds, you know?

[CkRtech]

Hey guys - I know you are currently discussing the circuit (and potential PCB) for the BA6592F-based RGB-YUV project, but I wanted to comment on Ace's post back on page 6 regarding adding component video to a launch model SNES as I have that one.

I pretty much followed what was here - http://www.sega-16.com/forum/showthr...l=1#post483965

My NPN was your typical 2N3904 from Radio Shack. After completing the circuit yesterday, the colors seemed a bit over-driven on my plasma. I ended up adding a 75 ohm resistor to the end of the output for the Pb & Pr, and it scaled the colors back to something much easier on the eyes (at least when paired with my display). I do still have a small issue of the faintest of vertical bars, however my circuit is also very much in prototype mode as I have fairly long wires hanging outside of the SNES.

A few questions -

1: Why put 66 ohms on the Y output? Is the Y output for S-Video (I grabbed my Y signal from the multiout connector) not spec'ed the same for S-video & Component video? I would just assume use the signal as it was, however I stuck with the 33 ohm x 2 series take that Ace mentioned in his post.
2: A user on nesdev mentioned going a different route for the Pb & Pr outputs by using a PNP transistor & going through your typical 220 uf + 75 ohm on your output line. Any thoughts on this? http://nesdev.parodius.com/bbs/viewt...&postorder=asc
3: I suppose this is mostly for Ace, but which outputs did you use on your SNES? It looks like you could panel mount RCA connectors, but not without tearing out some of the RCA shielding between the sound box and the back of the case. I suppose you could have abandoned this in favor of your external solution, but I think I am going to pursue the direct RCA connection route if possible.

Possibly some more questions/comments to make, but I am happy to finally be registered and posting on sega-16. Ace asked if any with a launch SNES have tried this mod, and I am raising my hand.

Long story short, it looks pretty good at the moment.

[akaviolence]

You're looking at 2.75 per board if we do 100, but Ace has final say in this since it's his circuit.

Seems high, how many sq in is the pcb?
I've laid out numerous pcbs and had them fabbed with Dorkbot, they do a medium run order that's $1/sqin! Great deal for US fabbed, 6/6 spec, double sided purple solder mask and double sided silk screen, and gold plating!
Are you trying to keep it through hole except the ba6592/4?
Let me know if you need help, i'm totally willing!

[akaviolence]

The circuit works no problem on my VA3 Genesis Model 1.

@Ace
I couldn't get this to work in place of the jrok encoder on a PC10 modded nes, any idea what I should look for?
I tried numerous variations of the circuit, but did not try a different 6592 yet.
I know the nes works through the jrok though, here's a vid.