Easy SNES/SFC YUV component video!

[evildragon]

I love how this thread has derailed to be NOTHING related to the original topic title.

[Chilly Willy]

FWIW, RGB levels from the Genesis I was using as a test machine averaged around the 3-4 volt range IIRC.

Holy crap! That can't be right... or better not be. Most encoders want the RGB inputs less than 1V. In fact, 0.7V P-P is fairly standard for RGB.

[evildragon]

I will check this tonight.. That would make a seriously bright picture on a CRT, which is backwards because the Genesis is usually a dark machine.

[Lastcallhall]

Yeah I'm probably wrong on that - I did a ton of measurements on it so I might have my numbers mixed up. I'll update once I'm in front of the system.

[Ace]

Remember one thing: check from the console's RGB outputs. This is the source of the RGB into the converter. I'm pretty sure the RGB out of the Genesis is quite strong as it's strong enough to make anything gray show up white and blend in with anything white on the screen (such as the clouds in After Burner II Stage 6) unless I place a voltage divider between the RGB inputs in my converter and the RGB inputs at the encoder.

I also noticed I made a mistake with the voltage divider as the schematics of the BA6592F show that you have to put a 560ohm pull-down resistor on the RGB lines. I know one thing for a fact: depending on the strength of the pull-down resistor you use in a voltage divider at the RGB inputs, the video gets sharper or blurrier. The stronger the resistor, the blurrier the resulting Component image.

[Drakon]

I love how this thread has derailed to be NOTHING related to the original topic title.

How so? We've been talking about the circuit from the topic title.

[evildragon]

How so? We've been talking about the circuit from the topic title.

I wasn't talking about the chip. I was talking about the title...

The title itself infers this is SNES talk, when in fact most of the talk is about getting the chip to work on a SEGA.

[Lastcallhall]

I found my notes - 0.7V from all three coming out of the chip.

[chessage]

The encoder is BROKEN, Chessage. How do you expect me to be able to check anything with a broken encoder (and I don't have any replacement encoders, so don't tell me to just swap encoder)?

By using a multimeter. You need to find out what's wrong by checking its voltage characteristics and comparing it to a working encoder on one of your SNES consoles. No swapping needed.

[Chilly Willy]

I found my notes - 0.7V from all three coming out of the chip.

Good... so that's not a problem.

[Ace]

Good news: I got my converter back up and running. Turns out I moved the 1uF capacitor on the red input in such a way that I made it short with Luminance and Green at the same time. So now, I decided I'd take a crack at it again to get the colors right. So just to make sure, how should I test the voltage at the RGB inputs? Do I measure AC or DC voltage and exactly how do I measure the voltage? From the RGB input pins to Ground or another method?

EDIT: Son of a bitch. Well, the encoder is intact, but the circuitry around the encoder is just completely messed up, so I'm gonna rebuild the circuit in its entirety again.

[Guntz]

So just to make sure, how should I test the voltage at the RGB inputs? Do I measure AC or DC voltage and exactly how do I measure the voltage? From the RGB input pins to Ground or another method?

When testing voltage, you have to make a complete circuit, so yes, put your multimeter's red contact onto an RGB line, and the black contact on a ground point.

I've heard the best way to test RGB voltage is to get the RGB output machine to display a white screen.

[Ace]

Okay, so that's settled, now what voltage setting do I need to use to test the voltage? AC or DC?

[lumclaw]

When testing voltage, you have to make a complete circuit, so yes, put your multimeter's red contact onto an RGB line, and the black contact on a ground point.

I've heard the best way to test RGB voltage is to get the RGB output machine to display a white screen.

Hmm. Could that be a cause for screen rolling?

[Guntz]

... Most home consoles and encoders I know of work on DC current, what do you think the right answer is?

Hmm. Could that be a cause for screen rolling?

You mean when a white screen is displayed? Well, I've only heard of such a phenomenon from someone playing Ninja Master's (Neo Geo) on a TV I can't remember. When you beat an opponent, the screen flashes white, which made the guy's TV roll until the flashing was done. I don't know what might cause that problem...