Sega genesis / 32x and component video

This is only a work in progress because I'm waiting on parts. I bought a jrok rgb to s-video / component encoder way back when just because....I actually can't remember why. Anyway the s-video circuit from the jrok sucks so I kept it sitting in a droor all this time along with a bunch of other encoders I bought. I've been talking to a lot of people on the sega16 forums lately and I was getting mixed messages about the genesis having jailbars in rgb. I've pretty much solved the jailbars in s-video to the point where they're as good as they ever could be. But the jailbars in rgb was another mystery. Now I was really confused because some people said the rgb has no jailbars and other people said the rgb does have jailbars. I finally got fed up with trying to figure out if the rgb has jailbars based on what other people have posted so I ordered a fairly cheap rgb to component encoder from ebay that's known to work fine with the sega genesis. The arguments continued on and I kept telling people to wait for my component encoder to show up....but then I remembered I had that jrok component encoder just sitting in my droor collecting dust for a number of years.

Now there's also this really massive thread on assemblergames where people had been trying to fix the jailbars in rgb. In the thread they went through a lot of different ideas, theories, and results. One person kept claiming that the jailbars were only present in the colour blue. Also the same person said that lifting vdp pin 50 from the genesis pcb decreased the jailbars. VDP pin 50 is the colour subcarrier so it's needed for the cxa1145 to encode colour in s-video, composite, and rf, but for rgb the colour subcarrier isn't needed.

I wired up the jrok to the genesis with vdp pin 50 still wired up and the picture was pretty awesome looking. The image had absolutely no rainbow banding, and extremely weak jailbars. I used sonic 2 as a testing game as sonic 2 is full of very bright red, green and blue colours so it's a great game to see exactly what's going on. The very weak jailbars were present in every colour, they were there in reds, blues and greens so that whole theory about the jailbars being only in blue is complete crap. Next I tried disconnecting vdp pin 50 from the pcb and *poof* the very weak jailbars completely disappeared on my tv! So the theory of disconnecting the colour subcarrier from the pcb to get rid of jailbars in rgb is completely true! The component video picture from the genesis is absolutely problem free on my crt tv, no rainbow banding, and no jailbars. Here's some screenshots taken when there was still weak jailbars before I disconnected vdp pin 50...but the jailbars were so weak my camera didn't pick them up:





Unfortunately my tv with component inputs is a 25$ garage sale machine so it's not the sharpest picture out there. But it atleast helps me test out things that output component video. So disconnecting vdp pin 50 cleared up the jailbars on the tv which is pretty awesome.

My capture card can't capture component video...but both component video and s-video have a luma pin so I was able to capture intesity without colour:



Here's a screenshot of the luma from the component video of the system with vdp pin 50 disconnected:



Not a huge difference...I guess the jailbars I was seeing on my tv were in the colour lines...unless the 32x is filtering the bars out somehow.

I've been busy with commissions but I felt like taking a day off from commission work. My component video capture device has been here for a while now so I unpackaged it and got to work with some component video screenshot goodness. The picture I got on the capture device was extremely unstable. I tried using different rgb to component encoders on my genesis system and got the same unstable effect. I tried my own software as well as the software that came with the capture device, changed all the software settings, but nothing would make it stable. The next logical step was to try adding component to the signal lines themselves. Since the picture is unstable I just assumed stability would be caused by luma and not the colour lines. First idea was to use a capacitor. I looked at the existing circuit on my rgb to component pcb and there's a whopping 1000 uf cap on the luma line right before it goes out the rca jack....so much for that idea. The next idea was to add a resistor, I added a 50 ohm resistor in between the rgb to component encoder and the capture device and suddenly the image became 100% stable!

Now for a sega genesis component video screenshot party.

First with everything as original (well pretty much)



Now with the colour subcarrier line lifted from the pcb at the vdp chip:



Let's see those same shots with the sharpness turned up ultra high.

Default wiring:



With the subcarrier lifted (vdp pin 50)



It seems that thread on assemblergames is completely correct about the subcarrier problem...win!

i dont have any jailbars on my jvc x-eye. its running component.


i didnt do anything besides rewiring 1 line on the cxa chip.

mvsfan wrote:

i dont have any jailbars on my jvc x-eye. its running component.


i didnt do anything besides rewiring 1 line on the cxa chip.

It all depends on how good your rgb to component converter is. I have two but only one of them was sharp enough to make the jailbars visible.

and i thought mine was sharp. Gundam wing Snes looks unbelievable on this setup.

on Genesis, Castlevania bloodlines looks great too.

quite a few games on the genesis have way too much composite blending for my liking though. it looks like crap on rgb/component.

thankfully they didnt use much of it on the snes.

on a side note, any idea how to reconnect the hard reset line in an x eye so sms mode works on the ED?

sofar thats the only thing i have disliked about the x eye in the 15 years ive owned it.

id really like to get an x eye service manual.

mvsfan wrote:

quite a few games on the genesis have way too much composite blending for my liking though. it looks like crap on rgb/component.

thankfully they didnt use much of it on the snes.

on a side note, any idea how to reconnect the hard reset line in an x eye so sms mode works on the ED?

sofar thats the only thing i have disliked about the x eye in the 15 years ive owned it.

I've never owned a x'eye so I've never looked into it. I didn't realize that the system doesn't come with a reset button. Personally I prefer the genesis in crystal clear pixel perfect video. Seeing "composite blurring" with sharp pixels doesn't bother me one bit.

I've never owned a x'eye so I've never looked into it. I didn't realize that the system doesn't come with a reset button. Personally I prefer the genesis in crystal clear pixel perfect video. Seeing "composite blurring" with sharp pixels doesn't bother me one bit.[/quote]

It does come with a reset button but apparently its broken somewhere along the line, where the ED cant switch into MS mode on that console. even krikzz has said so.

id like to get a service manual so i could trace it down and hopefully connect it like it is in a genesis 2.

Hey, you do not know if the IC cxa1145 also serves to neo geo mvs mod?, As the signal which also works that console is RGB. Hey read that some managed to get good image (like the arcade) for s-video and composite video, but for now I just got the picture eh black and white (for composite video), but not quite stable ... any suggestions?
thank you!
Greetings from Argentina.

CXA1145 is just an encoder.
I'm sorry, I don't understand... you're getting just black and white from your composite signal? Did you made a circuit resembling this one http://console5.com/wiki/CXA1145 ?

MVS system aren't notorious for sync issues, unlike superguns, so I don't think that's what your issue is.

exactly, only get black and white signal ... I'm using the manufacturer's diagram.





: )

Anyway, do not say if the diagram or diagram made ​​to make mention of RGB signals neo geo mvs, really do not know .... only a few people in Mexico who managed the mvs neo geo consolizar with cxa1145 IC bearing the Sega Megadrive.

You're 100% sure that you're on pin 20?
What is the composite output hooked up to?
Can you hook up S-Video instead?
PAL?
NTSC?
Analog?
Digital?

The diagram you posted looks correct for PAL.

This might be worth reading:
http://www.zipplet.co.uk/index.php/content/electronics_mdpal60

It can be connected s-video, but as my tv does not have s-video I can only connect to composite video, my tv is PAL and NTSC, I tried it on two different tv and not managed to get the color eh, only the image good quality.
Affectively, the pin 20 is composite video and that is where I connect the composite video cable. Question, the video mode is PAL and NTSC mode?