Dreamcast RGB > oversaturated colors

[Darkman]

Hello all, I'm new here.

Here's my problem - I rewired my fake Dreamcast "RGB" SCART cable to output true RGB. But what's really strange - certain shades of yellow, green, blue and red to some extent have a fluorescent glow(like they are oversaturated; other colors look OK). Is this normal? If not, can I do something to fix it?
The saturation controls on my TV don't work while in RGB mode.

Any info is greatly appreciated.

D.

[Lawrence]

You can't "oversaturate" RGB, that's the advantage of it.  For the same reason you can't change the tint.  What you see is, assuming your monitor is properly calibrated, how it should be.  If it's way off it could be that your monitor is overdriving the colours in which case adjusting the contrast or brightness should solve it, but the glorious colours of RGB are the reference, whatever you're used to with other methods are, in fact, the wrong ones.

[giantgonzolez]

Hello all, I'm new here.

Here's my problem - I rewired my fake Dreamcast "RGB" SCART cable to output true RGB. But what's really strange - certain shades of yellow, green, blue and red to some extent have a fluorescent glow(like they are oversaturated; other colors look OK). Is this normal? If not, can I do something to fix it?
The saturation controls on my TV don't work while in RGB mode.

Any info is greatly appreciated.

D.

There may actually be another explaination to this.
Some televisions exibit a problem called "red push" where the reds are oversaturated for example.
I guess the same thing can also happen with other colors.
What the problem may actually be is that tv manufacturers intentionally misadjust tvs so that they will stand out in electronics department of a brightly lit store.
Unfortunately the only way to fix this problem may be to adjust stuff in the "service menu" of your tv.
The service menu is MUCH MUCH more advanced than the regular menu, and you can usually adjust stuff like geometry, color temperature, tilt, rotation, horizontal size, vertical size, horizontal position, vertical position, and many other advanced settings in the service menu.
There's usually a code or a trick to get into the service menu of your tv, and each tv manufacturer usually has a different code or trick.
The code or trick is usually to press several different buttons on the remote in a certain sequence and in a certain amount of time.
It's like a combination/password to get into the service menu.
Now changing the values in the service menu can mess up your tv if you're not careful.
The first thing you should do before making any adjustments is that you should write down what all the original factory values for each setting in the service menu was before you make changes to any setting in the service menu.
The best thing to properly calibrate any display is an professional ISF calibration which usually costs several hundred dollars.
Pro ISF techs have very advanced equipment that they use to test and adjust your display and they make many very advanced adjustments in the service menu of your display.


 

[Darkman]

Thanks for clearing a few things up. I guess my TV is out of whack. After all, it's over 15 years old. I'll try to find out how to get into tha service menu.

D.

[rfm]

"You can't "oversaturate" RGB?" Huh? What kind of nonsense is that?

If I connect a JAMMA board with its several-volt RGB levels directly to the input on a Euro SCART monitor, I certainly can overdrive the RGB circuitry and likely get exactly the "glowing" effect described here. Why do you think the XRGB-2 has that switch to attenuate levels for these boards, which you mention in your sales pitch for the 2 versus 2+ on your sales page?

If I connect a Megadrive to most monitors without the 75ohm resistors on the RGB lines I'll likely overdrive as well.

A wild guess here, but since this is a converted-to-RGB cable for Dreamcast, if it doesn't have the 220 microfarad capacitors on the RGB lines it just might exhibit this result; I know a Super Famicom without the capacitors exhibited exactly that on one Sony I tried it on.

[Lawrence]

May I suggest, my uppity friend, that you keep your tongue civil on these forums?

Oversaturation is not the correct term in this discussion.  The signal is overdriven, not oversaturated.  Oversaturated refers to a different aspect of colour reproduction.

[Endymion]

Just a dumb suggestion that you may have tried already, but it definitely is worth repeating--check your work again. If the signal is being shorted anywhere you could easily have a working picture with more of one colour and less of another.

I had this problem with the first SCART RGB Dreamcast cable I reworked for my monitor. Everything was soldered properly but any time I set the plug casing on it I got an overly red image, the problem was that open wire was touching the plug casing--which was coated with a metallic paint for shielding. I just taped up the exposed wire and all was well.

By the way what's a "Fake Dreamcast RGB SCART" cable? :lol:  

[Darkman]

OK, it seems the colors I get are indeed the right ones. Only a few games have this effect(unfortuantely, my favorite games). I guess I'll have to get used to that. At least those annoying(sp?) diagonal stripes while in 60Hz mode are gone forever .

To Endymion:
I called that cable "fake" because it had R, G and B lines soldered correctly(220uF caps too!), but didn't have pin 7 soldered to ground on the Dreamcast side. The result - only composite output. What I did - soldered pin 7 to ground and resoldered composite line to composite sync pins.