Will this work?

[atheistgod1999]

I got a composite video as sync RGB cable for my Genesis 1 and I'm getting jailbars on blue. I heard I should use composite sync to do this, but I don't want to buy another cable. I came up with the idea of coating the tip of the composite video pin on the cable with an insulator and get a little metal trace on the back from the sync pin to the composite pin. Will that work? I didn't try it yet.

[Guspaz]

If the guy making the cables used the Genesis cable as the base and then stuck the SCART on the end, it's possible that the CSYNC pin is wired all the way to the SCART connector where it's not connected to anything. You should open the SCART connector and see what's going on in there, you may simply be able to rewire things inside the SCART box.

[atheistgod1999]

I got it open. Which wire carries the csync?

[Guspaz]

Well, you'd need to use a multimeter to test continuity between the pins on the connector and the wires in the SCART connector, I guess? The sync wire, if it exists, wouldn't be connected to anything. You can find the pinout online, but keep in mind that the pinout of the connector and socket are mirror images, so the top left pin is sync on the socket, but the top right pin is sync on the connector.

Even if you find the sync wire, you might need to wire some stuff in series with it: I'm no expert on this, and somebody else here more knowledgeable could tell you if the raw sync signal can be passed to the display or if you need a resistor or something.

EDIT: Looks like both a capacitor and a resistor go in series with csync?

[Fudoh]

Looks like both a capacitor and a resistor go in series with csync?

resistor is optional, but the capacitor is a must. No picture without it.

atheistgod1999: you need to open the MD side of the cable and check if the sync pin is wired up at all. If it's not, you can remove the cable from the from the video output and connect it to the sync output instead. You still need to add that capacitor though.

[Guspaz]

If the megadrive/genesis side of the cable is not easy to open, I'd try with a multimeter first, before cutting it open...

[atheistgod1999]

I opened the DIN part of the cable (it had a button that had it come open without needing to cut anything) and I found that the csync pin is unused. My dad's been soldering since the 1970s, so he could switch the composite wire connection to the csync pin, but he said it could cause voltage problems that could break my Genesis. Mine's a non-TMSS one, so I really don't want that to happen. Can someone like Skips confirm that it's harmless to switch the wire from the composite video pin to the csync pin to turn it into a csync RGB cable?

[Guspaz]

Fudoh is pretty darned authoritative...

As Fudoh said, you need to do more than just change the wire.

[Fudoh]

you can't do any damage. Just switch the output pin on the MD end and within the scart header add a capacitor (between 100 und 220 uF capacity, + pin facing the MD) to the very same wire.

[atheistgod1999]

you can't do any damage. Just switch the output pin on the MD end and within the scart header add a capacitor (between 100 und 220 uF capacity, + pin facing the MD) to the very same wire.

Just wondering, why do I need a capacitor? Why does a csync wire need a capacitor but not a composite video one?

Also, Fudoh, I'm using a Genesis (I live in North America). Does that make a difference?

[BuckoA51]

Because Sega screwed up the csync output.

[Unseen]

Because Sega screwed up the csync output.

I don't think it was ever meant to be connected to a TV-like input - the signal comes directly from the video chip and since there is a 2.2k pull-up resistor on the line I suspect the driver in the chip is not very strong.