RGB help with the Retro Duo. Update: Figured it out, w/pics!

[perfectmf]

Hello everybody! Loooong time lurker, first time poster. On to business.

I've decided to try and connect my retro duo to my zenith screen using the rgb signal. I've made sure to connect the proper pins to the corresponding one on the screen's board. +7.5V, Ground, csync, red in, green in, blue in, ground, and 5v. What I got was this:



Sharp picture sure, but, it's all blue. Triple checked each wire, everything was straight. So then I added a 68ohm resistor (What I've read online is to use a 75ohm but 68 is all I could find) and a 220uf cap to the R,G, and B output on the duo's KA2198BD. I ended up getting the same result. So I thought to myself that I should check out the composite signal, perhaps it's not that bad? Hooked it up and got this:



I don't think I would personally be able to take the color bleeding, the scrolling from top to bottom of the interference or whatever it is (you can make it out at the top of the screen as well as over the shield bar and boost/brake bar) and other image issues I have with composite within my portable. After all this I took out my Genesis 3 to find out whether the problem may be with my screen accepting an RGB signal. This is what I got:



Also this:



It's much better than the Retro Duo. *Update* Figured out the problem, read below.

[nobble]

Did you led mod the screen? Cuz i've heard it can turn out kinda blue from the leds.

[perfectmf]

No, I did not. I should've mentioned that. Other things that I neglected to mention is that the screen and Retro Duo are still running power from the wall plug, and I got the 7.5V and 5v needed to run RGB from the 7805 regulator on the back of the board of the screen. Aside from that I can't think of anything else.

[nobble]

No, I did not. I should've mentioned that. Other things that I neglected to mention is that the screen and Retro Duo are still running power from the wall plug, and I got the 7.5V and 5v needed to run RGB from the 7805 regulator on the back of the board of the screen. Aside from that I can't think of anything else.

Hmmm...

That is odd.

Maybe you have a bad duo.

Other than that idk what to tell ya.

[perfectmf]

Well I figured out what the problem was, I incorrectly connected the wrong pins from the KA2198BD to the screen's board. If you look at the chip's datasheet http://www.datasheetcatalog.org/datashe ... Xvvrux.pdf You'll notice that RGB output are on pins 21, 22, and 23. What you really need to do is use pins 2, 3, and 4 which are RGB inputs. I can't exactly tell you why this is (video signals and resistors aren't exactly my area) but my guess is after looking at the datasheet under features you can see that there is a 75ohm driver for use with the RGB outputs, which again I'm guessing the screen doesn't need the signal through a resistor. So, again forget the ouput pins. Use pins 2, 3, 4, and 10 (csync) to get RGB with your PS1/Zenith screen. The pic is a bit blurry but for those that may not know where pin 1 starts (in-grooved dot on chip in most cases) it's a reference. Also I apologize if this has already been discussed but I literally spent hours upon hours reading on not just this site but all over the internet for a solution. I would usually get bits of info here and there but never could I find it collected in one place or a concrete answer.



Here are some photos of games with the RGB fix:




I took these pictures with some weird lighting issues and at odd angles but it loooks MUCH better in person. Especially Star Fox

[nobble]

glad you fixed it. Can't wait to see your portable!

[RGB_Gamer]

I know this thread is old, but where can I get plans to do this mod? Is the NES part also RGB?