Genesis component out problem

[geiger9]

Hi everyone,

I have a Genesis set up with a SCART to Component adapter. Some of my games do this:

https://www.youtube.com/watch?v=eHhSlgyZ5Bw

I don't have a lot of games to test but it has this problem with the bonus stage in Sonic 2 and random parts of Shining Force II. Games like Wolfchild and Desert Strike work fine.

My TV is a Sony KDL-40EX500 and the Genesis is a model 1. This is my SCART->Component converter

Any help would be appreciated.

[Fudoh]

Good chance that the RGB signal levels are simply too high (especially with bright or even fully white screens). You might be able to fix this by adding stronger resistors to the RGB lines (and maybe the sync line as well). If you have already resistors in the RGB lines, they're probably 75 ohm. You can try to replace them with 150 or 180 ohm rated ones.

[kowal]

I use this on MVS
and sync was too strong 50-150R is correct

[geiger9]

Fudoh: I will admit that I have very little knowledge of electric circuits. I know even less of soldering. With that in mind, do you mean that I would have to take apart my SCART cable and solder some resistors to something?

[Ed Oscuro]

Yes, exactly that. Each little cable which is connected to a pin needs to have a resistor added between it and the plug.

Since I'm curious, does anybody know of Genesis / Mega Drive RGB cables that are set up correctly for a RGB to component transcoder, or vice versa?

[Fudoh]

none are, since all the cables are based on some internet schematics, but nobody ever cared about actually measuring the peak levels and bringing them down to the proper level.

[geiger9]

Yes, exactly that. Each little cable which is connected to a pin needs to have a resistor added between it and the plug.

Hmm. Would you recommend that someone with no soldering experience take on such a job? Is it complicated?

Edit: Here are some pictures I took of my cable. I noticed that not all the wires are connected. Should I be concerned? And those things attached to the green, blue, and orange wires... aren't those capacitors?

[muckyfingers]

Try putting a 220uf 10v-16v electrolytic capacitor on sync line (yellow wire in your picture) just like you have on the RGB lines. This solved my issues with using my Genesis with a YUV converter and using it on a PVM unit as well.

[geiger9]

So since there are capacitors on the RGB colored wires, do I also need to add resistors to that? Or should I just be fine with adding a capacitor to the sync?

[muckyfingers]

I would just use a cap on the sync line, my scart cable is the same as yours with caps on the RGB and no resistors. I am using the same converter as you are as well. The only issue I have encountered is that the Genesis start up screen (the "Produced By...") will be purplish at first and then all colors are fine once in gameplay. I get this issue with the "SEGA" screen on Sonic the Hedgehog, once the title screen comes up it is fine again.

[geiger9]

I would just use a cap on the sync line, my scart cable is the same as yours with caps on the RGB and no resistors. I am using the same converter as you are as well. The only issue I have encountered is that the Genesis start up screen (the "Produced By...") will be purplish at first and then all colors are fine once in gameplay. I get this issue with the "SEGA" screen on Sonic the Hedgehog, once the title screen comes up it is fine again.

So I added the cap like you suggested and it worked... for a while. It seems that for the first time testing it, it was fine. The screen didn't black out or anything. I continued to play and then the problem came back. THEN, the problem started happening in parts of the game where it didn't before! Now I feel that I made it worse. What could be the cause of this?

[muckyfingers]

Good chance that the RGB signal levels are simply too high (especially with bright or even fully white screens). You might be able to fix this by adding stronger resistors to the RGB lines (and maybe the sync line as well). If you have already resistors in the RGB lines, they're probably 75 ohm. You can try to replace them with 150 or 180 ohm rated ones.

You were correct, I just put a 75ohm 1/4watt resistor on each RGB line and it fixed the purple tint on the white screens.

So I added the cap like you suggested and it worked... for a while. It seems that for the first time testing it, it was fine. The screen didn't black out or anything. I continued to play and then the problem came back. THEN, the problem started happening in parts of the game where it didn't before! Now I feel that I made it worse. What could be the cause of this?

Try putting 1x 75ohm 1/4watt resistors in series on each of your RGB lines, before the capacitors that are already on there.

[geiger9]

Try putting 1x 75ohm 1/4watt resistors in series on each of your RGB lines, before the capacitors that are already on there.

I'll be heading to the parts store tomorrow to pick some up. Tomorrow also happens to be my graduation so it may not get done right away. Thanks again.

[orbus]

none are, since all the cables are based on some internet schematics, but nobody ever cared about actually measuring the peak levels and bringing them down to the proper level.

There must have been an official SCART cable in Europe, no? Was it not RGB? Seems silly to have the pins available on the output port and not put out a cable to use them.

EDIT: A little searching around on google suggests official ones exist (or did exist) at least in France. But they seem to be rare as hens' teeth these days.

[geiger9]

So my electronics store didn't carry 75 ohm resistors but they did carry 150 ohm and said to do this:



Is this okay?

[Fudoh]

yes, this works.

But you can also remove the existing resistors (likely 75 ohm) and put in single 150 ohm resistors instead. That is, if there are resistors under the shrink tubing. If there are no resistors at all in your cable, go with 150 ohm right away. Many cables with 75 ohm resistors in place still produce dropouts.

[geiger9]

So my soldering job took a turn for the worse. I was able to successfully solder the resistors onto the blue and green wires but then as I was working on the red, the soldering broke off on the blue wire. There just wasn't enough wire to work with. Soooo I did something drastic: I cut the cable off from the SCART plug entirely. I stripped away the insulation below the cut to give me more length to work with. This is what it looks like:



What is up with the exposed wire?

Also here are some things I noticed about the wiring on the SCART plug:

Pin 4 is connected with a wire to the edge of the connector
Pins 18 and 19 are connected together

Is this okay?

[Fudoh]

17, 18, 4 and the outer piece of metal can be connected - they all carry ground. 19 shouldn't be connected at all.

If you're soldering the cable from scratch, leave out the capacitors. They're usually not needed on a MD RGB cables.

The "exposed" wire was likely used for ground. Wire it to one of the above pins.

[geiger9]

Sorry that took so long, life gets in the way.

So I left out the capacitors as Fudoh suggested and soldered the resistors on the R,G,B wires and my god, the cable still worked afterwards. It works but it STILL has the original problem of the screen blinking

[Fudoh]

put the same (or similar) resistor value on the sync line as well.

[geiger9]

I'll try it. Also, the video now looks really green. What caused that?

[NinSEGA]

Sorry to derail/hijack your thread, but I have a similar situation However, instead of getting a flickering picture, I get a black screen. Here's my setup-

SEGA Genesis Model 1 -> RVB SCART cabel peritel connected to Retro Gaming Cables' EURO SCART to JPN SCART adapter -> GAME IN port on XRGB-3 (XRGB-3 has latest English firmware) -> DVI-D and audio connected to Monoprice's DVI-D+R/L to HDMI adapter -> Monoprice's DVI+R/L to HDMI adapter connected to PlayStation 3D Display via HDMI.

I did get sound, but I tinkered with a few settings and then I lost it.

My S-video port works perfectly with my N64 and my composite port only works in B0 mode with my Saturn. Composite doesn't work at all with my Genesis (but works fine with a direct connection to a TV).

A list of optimal settings for each option is needed in order for me to get this working please. Thank you.

[geiger9]

Left with a darker, greener image, I decided to unsolder everything again and also tear up the 8 DIN side of the cable. When I did, I discovered two things:

1. There were already 75ohm resistors on each of the RGB wires. They look about 75% smaller than the 150ohm resistors I have so I guess they are 75?

2. The cable was wired for composite sync. I figure if I came this far, I might as well wire it for raw sync.

Just to recap, here was what my cable looked like originally:

75ohm resistors + 220uF caps on RGB wires
Composite sync with no cap

When I first modified my cable:
75ohm resistors + 220uF caps on RGB wires
Composite sync with 220uF cap

Now the SEGA intro screen with Sonic running across it blinked and didn't display properly. This still occurred though.

My second modification of the cable:
150ohm resistance in total with NO caps on the RGB wires
Composite sync with 220uF cap

The SEGA intro screen still had the same problem but now everything was darker and things were really green. Still had the issue that you could see in the video I posted.

So I'm thinking my next step will be to put 150ohms +220uF caps back on the RGB wires and a 220uF cap on the raw sync wire. Thoughts?

[Billkwando]

Did this ever get resolved?