So.... Some SNESes output YPbPr.....

[Ziggy]

Well where in the world are you? PAL is your standard? What I'm getting at is I don't know if this is happening with PAL games running in 60Hz on a PAL TV, or whatever combination.

Another thought is that some HDTVs don't like the 240p signal from the SNES. That could be one reason.

My only other thought is that perhaps it has something to do with the way you wired it up. I'm assuming you wired in switches so you can switch between 50 and 60 Hz? Perhaps the switches, or something else in the wiring, is causing the problem. I was planning on hard wiring my PAL SNES, effectively turning it into an NTSC SNES. Like I said before, when I'm done modifying it, there should be no difference between my PAL SNES and an actual NTSC SNES. At least, that's what I'm led to believe from everything I've read.

[elmagicochrisg]

Well where in the world are you? PAL is your standard? What I'm getting at is I don't know if this is happening with PAL games running in 60Hz on a PAL TV, or whatever combination.

Europe. So indeed PAL games running in 60Hz on a PAL 60Hz compatible TV.

Another thought is that some HDTVs don't like the 240p signal from the SNES. That could be one reason.

Possible, but unlikely since I tried it on 4 different TVs of which 3 CRTs.

Five actually with the projector...

My only other thought is that perhaps it has something to do with the way you wired it up. I'm assuming you wired in switches so you can switch between 50 and 60 Hz? Perhaps the switches, or something else in the wiring, is causing the problem. I was planning on hard wiring my PAL SNES, effectively turning it into an NTSC SNES. Like I said before, when I'm done modifying it, there should be no difference between my PAL SNES and an actual NTSC SNES. At least, that's what I'm led to believe from everything I've read.

I've thought of that too. Only thing is, when I do a mod I really take my time. So no bad solder joints, fresh wire, solder with lead. Besides, it's not such a hard mod. Few things can go wrong...

I don't think that's the problem. Still, you could be right...

Also, don't know if the signal is PAL 60Hz or NTSC 60Hz after the mod...

I know European Dreamcasts are PAL 60Hz and European PS2s are NTSC 60Hz.

[Ziggy]

Well that really sucks, but I guess I'll have to wait and see. I have an Australian PAL SNES by the way. I don't know if they're the same as European SNESes. I know little about PAL video things. And I had no clue there was a "PAL 60Hz" and "NTSC 60Hz" difference.

[theclaw]

Have you tried an NTSC game? Some PAL SNES games were reprogrammed for 50hz and would have issues at 60hz anywhere. Super Mario World, Super Mario All Stars, Starwing, Pilotwings...

PS2 in-game should be identical in USA and Europe. American PS2 also setting NTSC color at 60hz, PAL color at 50hz.

Older consoles like SNES, Megadrive, SMS, PS1, Saturn, etc, determined color format largely separate from 50hz and 60hz. You must modify both to change both. All of their NTSC models by default would attempt to output the dreaded NTSC50 at 50hz!

Yup that includes Nomad. Hence NTSC50 is part of why composite-based replacement screens are harder to get proper color at 50hz. The original Sega screen was fine since it used RGB.

[Ziggy]

Older consoles like SNES, Megadrive, SMS, PS1, Saturn, etc, determined color format largely separate from 50hz and 60hz. You must modify both to change both.

That's exactly right, as I've found out more or less the hard way.

I finally got around to modifying my PAL SNES. Like I said, it's a 1chip SNES. So I lifted leg 111 of the PPU and grounded it, and changed X1 to the appropriate value. When I tested it, it worked but the colors were all wrong. I could tell that it was outputting a 60Hz signal because the image was stable on my TV, but the colors were definitely wrong. So, I did a little searching and found that pin 9 on the S-RGB video encoders control NTSC/PAL. Comparing it to my NTSC SNES mini, grounding pin 9 outputs PAL and 5v outputs NTSC. So I lifted that pin and attached it to 5v. Now everything appears to work perfectly. AFAIK, I have an NTSC SNES now.

Moreover, the old ENC encoders have a NTSC/PAL pin as well (in consoles with two PPUs).

There's a ton of guides out there to modify a SNES for 50 and 60 Hz, but NONE of them mention being able to switch between PAL and NTSC output. I guess because 99% of the people doing the mods are only doing one of two things: People in PAL regions wanting to play their PAL games in 60Hz on their PAL TV. Or people in North America wanting to boot a game like Terranigma in 50Hz and then switch it to 60Hz after the check. Neither one of these cases require switching between NTSC and PAL. Though it would be really simple, all you would have to do is add another SPDT switch for NTSC/PAL. Or use a 3PDT switch to select between PAL 50Hz and NTSC 60 Hz.

My NTSC SNES in a PAL shell...




Now...

To actually post about something on topic!

I've still been looking into this YPbPr mod. I'm trying a few different things right now, and I think I'm onto the "correct" way to do it. Finding the time to work on it though is something else.

[theclaw]

AFAIK normally Europeans with access to RGB have no need for NTSC or PAL color mods. Australia and some other places had it worse. 50hz minus RGB.

[Jamisonia]

The biggest problem being with the YPbPr mod right now is we have discovered the Pr and Pb lines output ~3.3V. This is far too high to input into a consumer TV, and I personally recommend that nobody further attempt to, unless adding something to the lines that reduces the voltage and amps the signals.

Ziggy has been working with 6dB amps as suggested by a guy at NESdev. The problem he's running into is that the amps want the signal voltage to be far lower than it presently is. We are not sure of how to reduce the voltage without reducing the signal strength. Our lack of electronic knowledge is starting to show. If any has any ideas let us know!

[Ziggy]

Yeah. Basically this thread has been a train wreck, but we now KNOW exactly what needs to be done... to do it the CORRECT way. What needs to be done (in regards to Pr and Pb since Y works perfectly) is actually pretty simple. Kill the voltage then pass it through an amp.

I got some 6dB video amps, as suggested by Kyuusaku on the NesDev forum, and wired them according to their datasheet. What I didn't realize was that there's too much voltage on the Pr and Pb lines for the amp to input, so it didn't work. Luckily, the amp has some sort of protection against this so it simply just didn't output the video rather than blowing up the amp.

A suggestion I had a ways back was to take Pr and Pb from the inputs rather than the outputs of the encoder. This idea was shot down because the signals are actually weakened before being input, and we were only looking for ways to amp the signal at the time. But now it seemed like the perfect way to test the amps. I measured the voltage from the input pins and they are substantially lower than the output pins. So, i wired the Pr and Pb input pins to my amp (with a 1k resistor to ground on the inputs of each amp) and it worked.

There's a small problem though. It made the composite output all green. I guess because Pr and Pb pass back through the encoder to make composite, tapping the lines there some how messed up composite. But that's OK, because at least I know I'm on the right track. The component output looked great, the colors looked just about right.

For a few reasons, I'm gonna ditch the amps I'm using now and go with a different one. So, I have to order new amps and a mess of caps, and then hopefully I'll get this working 100%.

[elmagicochrisg]

There's a small problem though. It made the composite output all green. I guess because Pr and Pb pass back through the encoder to make composite, tapping the lines there some how messed up composite. But that's OK, because at least I know I'm on the right track. The component output looked great, the colors looked just about right.

I guess a workaround with a switch in the right place might help fix that problem?...

Flipping the switch would then switch between composite and component...

[Ziggy]

Nah, I'm not worried about it. Taking Pr and Pb from the input pins was just a way to be able to test out the amps without the voltage on the lines. Now that I know it works, I'll just take Pr and Pb from the outputs pins again, but kill off the voltage before inputting them into the amps. I'm hoping that will stop the problem. If not, well, I'll cross that bridge when I get there.