Questions about s-video mods for model 1 sega genesis (cxa1145)

i only have a very basic understanding of electronics, and i was going through all the different mods ive found online for getting s-video out of the cxa1145 sega genesis console.

recently i tried this guys advice, viletim!, on sms power
http://www.smspower.org/forums/viewtopic.php?t=11586

it was just a transistor with a 27 ohm resistor...it looks a lot better on my old crt t.v., but i didnt like the color...im color blind so i dont know if that was just my own personal issue. for the chroma i swapped the 27ohm resistor for a 1k variable resistor i pulled out of a broken stereo...played with that a bit, and am happy.

but is this right, safe, am i going to fry my t.v.?

i ask because i found and lost an 1992 sony data book a long time ago, it just resurfaced. i looked at it this morning and in the back there is this application note for the cxa1145p/m on how to get S-VHS out of the chip.

it involves running the C output through a band pass filter, the Y output through a delay line then both through a second cxa1145 chip. nothing i have seen online suggests that you need to do this.

what really is the best way to get s-video out of the sega genesis?

i dont have a scanner right now, otherwise id post a picture of the schematic. if anyone is interested i probably can get access to one.

 

No, you shouldn't damage anything. It would probably be wise to add 5-10 ohms in series with the pot, just so you can't dial the resistance all the way down to zero, which is the only way you could really hurt anything. It's not that critical anyway.

That's probably just to try and prevent interference from the luminance (Y) channel. Without it you might notice incorrect colour splotches appearing in areas of high contrast (see here). You shouldn't need it, it's just trying to improve things a tiny amount at the expense of extra complexity.

I've never used the CXA1145 but I built an s-video/composite output for my (RGB) Supergun using an AD722. That produces pretty good s-video output, but it can vary hugely - you can get horrible artifacts around the edge of polygons, such that it's actually nicer-looking if you use composite!

Kev's right that it would look a LOT better using RGB. Try using this method. From the datasheet here (page 2) you can see that the pins are the same between the CXA1145 and CXA1645 so it should be identical.

Stone

 

thank you for that information. rgb would be nice, and easier, but i dont have the money for that right now. my t.v. only accepts composite, coaxial, and s-video.

down the road id like to get a large flat screen t.v., then id probably go for the rgb at that time.