Removing RGB jail bars idea?

[MEGADRIVE Jeroi]

So lifting pin 50 cause jailbars to dissaber from RGB? So this is usable thing on my Combonent circuit also if it causes troubles with jailbars to the combonent adapter.

[Drakon]

So lifting pin 50 cause jailbars to dissaber from RGB? So this is usable thing on my Combonent circuit also if it causes troubles with jailbars to the combonent adapter.

Yes your combonent circuit would probably have the same effect.

[TrekkiesUnite118]

well lumclaw try lifting vdp pin 50 I did notice a difference. But it's very easy to bridge the pins on the vdp just to warn you. And it can be difficult un-bridging those tiny pins if you spend all your time posting on forums but never actually doing any mods like some people. Lift vdp pin 50 and lose the ability to have s-video....and fix up your rgb cable.....and that's really all I can think of.

Or you could try disconnecting it further along. You don't HAVE to lift pin 50, you just have to stop the signal from reaching the encoder and getting close to the RGB lines assuming it's the cause.

And you're really not helping yourself here. Your continuing to make yourself look like an arrogant prick with the way you are currently posting.

[Drakon]

I can't help how you interpret my posts but never actually wiring things up won't help you figure out what works I can gaurantee you that. Stuck my 32x into my second system that has pin 50 of the vdp lifted and the s-video now has....scrolling weak jailbars. I guess the colour subcarrier is needed for some kind of stability even in the 32x.

[TrekkiesUnite118]

I can't help how you interpret my posts but never actually wiring things up won't help you figure out what works I can gaurantee you that. Stuck my 32x into my second system that has pin 50 of the vdp lifted and the s-video now has....scrolling weak jailbars. I guess the colour subcarrier is needed for some kind of stability even in the 32x. Anyway using an external rgb to component adapter seems to get rid of all flaws when pin 50 is lifted.

We are not talking about S-Video. We're talking about RGB. Of course your S-Video signal is going to be screwed up without the Subcarrier signal. It's completely unnecessary for RGB though.

[Drakon]

The 32x isn't using the subcarrier from the genesis it's only grabbing rgb and sync and generates its own subcarrier. Anyway using an external rgb to component adapter seems to get rid of all flaws when pin 50 is lifted. I don't have a component or rgb capture device so I can't confirm the lifting pin 50 trick as being 100% rgb perfect but on the crt tv it looks perfect.

[omp]

Could it be that, since when a 32x is connected, some of the graphics (background) are done by the mega drive or genesis, hence why the screen goes iffy with pin 50 disconnected? There is something I want to look at doing, may have a quick minute to do it soon, and that is to disconnect pin50 and using shielded cable run my own connection point. Thoughts on that? To me that should solve the "getting interference" train of thought. I may need to try my mega drive on the lcd tv I got to introduce jailbars (have never tried that, since I am happy with the video on my crt).

Also as an edit I should mention that my mega drive has been region modded, so it has an external crystal oscillator in it. If that makes a difference, I am not sure.

[Drakon]

A subcarrier should be a very weak signal I doubt it's the trace leaking interference. But I don't know you can try it if you want.

[lumclaw]

If only we had someone who owns both an LCD with ordinary RGB SCART input, plus an unmodified NTSC model Genesis and Master System. It seems odd to me how jailbars appear more prevalent on the NTSC consoles.

Were these bars as big a problem in Europe... I'm sure we'd have heard about it from PAL console owners.

[MEGADRIVE Jeroi]

Here with RGB there are noticable like 10cm close to the 32" LCD that blue and rest colors has jailbars. From 3meter, it's a crystal clear picture. Other problems are the right down corner Video VDP noise. Third problem is VDP auido noise which is greatest when white color is shown or gone. If somebody develops filter to take VDP noise (CCAM with OPA chip supposed to kill audio noise) on video and Audio, surley one would be the Biggest reputation point counter ever.

[Drakon]

I did some more wiring and testing. I wired up the 32x rgbs output and power and ground from the 32x so I could power the rgb to component pcb from the 32x. Powering the component board from the 32x is important as my genesis is already pushed to its power limit using a s-video mod and the mega everdrive, powering an additional component board would probably cause audio buzzing. The results were as to be expected. RGB to component from the 32x sitting in a genesis with pin 50 of the vdp lifted gives a 100% problem free component picture on the crt (it's actually very beautiful, more perfect looking than I expected). RGB to component from the 32x sitting in the genesis without pin 50 of the vdp lifted brings back the very weak jailbars. So the 32x has no effect on the jailbars in the rgb the only thing that changes them so far is lifting vdp pin 50...or possibly lifting the pin from the cxa1145 that gets the colour subcarrier signal (but I havn't tried that yet). Of course if I had a rgb or component capture card it would be much easier showing the difference.

[lumclaw]

What pin would that be on Master System?

[TrekkiesUnite118]

See that's a very useful post. So I guess that pretty much settles it for the time being. It seems that the RGB jailbars do in fact come from the Subcarrier causing some kind of interference somewhere along the line.

[lumclaw]

Yeah this issue existed before Genesis was conceived. For whatever reason Sega didn't/couldn't fix it there, in model 2, or IIRC even by the time of model 3.

Perhaps its roots are found in Mark III where they first introduced RGB. (I don't know if SC-3000 computer has an RGB vdp)

[Drakon]

See that's a very useful post. So I guess that pretty much settles it for the time being. It seems that the RGB jailbars do in fact come from the Subcarrier causing some kind of interference somewhere along the line.

Yeah we definitely know it's some sort of a subcarrier thing. What I need is someone with a more sensitive tv to try this trick out. Just as long as that person doesn't mind losing the ability to have s-video, composite, and RF. Since the subcarrier comes right from the vdp and disconnecting the subcarrier at the point of the VDP fixes it...we can just assume that the vdp is the source.