S-video/Composite for 2600 Jr.

[Starfire]

Well I've seen about 15 mods for video for 2600's but all of them are for the large systems, not the junior. I've blown about a day here on trying things and have seemed to have gotten a good luma signal but the chroma is killing me, I just get tons of bleed or nothing at all.

 

This is the mod I'm using: http://gamesx.com/wiki/doku.php?id=av:2600_s-video_mod and the luma is great, but the chroma seems to escape me. I really don't care if I get svideo it can be just composite but with all the color bleed the RF looks better (I've disabled the RF now in an attempt to get better color).

 

I've searched and searched but nothing seems to pertain directly for the junior and the junior has a TC4050 built in (that's where I'm pulling the luma) anyone help?

 

Thanks!!

[Starfire]

Well after more tinkering I seem to have gotten a color signal but now anything red or with red aka browns, etc is really weak anyone have suggestions?

[Starfire]

Well after all that I ended up ditching all the circuitry, I had guessed that the resistor values for mixing the luminance were wrong giving me the bad colors. So I made a board with 4 potentiometers so I could adjust the mix and yup my guess was right, I ended up getting a good picture with no transistors, just a mix of luminance and chrome off the TC4050 already present in the junior. I'll post the values here later for future reference.

[+iesposta]

So did you get s-video or just composite, or both?

[reverendshoebox]

Values would be greatly appreciated - I was planning on trying this mod myself!

 

What you ended up with sounds a lot like the Ben Heckendorn 2600 Jr.mod, though he gets chroma from a different spot and recommends removing the 4050: http://benheck.com/classic/Question3.htm

 

-=ShoEboX=-

[Starfire]

Ok I made instructions on what I did, I did not test for S-Video, if I get around to it I will try it but works pretty good for composite. The resistor values aren't common sizes, this is what I measured from the 4 pots that I then replaced with the resistors, I just mixed and matched to get values within a couple ohms. I really didn't see any improvement when I ran the outputs through a transistor for amplification and I have no idea if this conforms to composite standards (I'm sure it doesn't)

 

 

[ApolloBoy]

Get one of the 2600 boards here and forget about anything else: http://electronicsentimentalities.com/Assembled%20Mods.html

[Starfire]

I'm sure that works great but for a few bucks I'm happy, we get spoiled nowadays sometimes these old 2600 games look better not being pixel perfect. I'll probably get one of those down the road but going for a harmony cart first.

[Osgeld]

Ok I made instructions on what I did, I did not test for S-Video, if I get around to it I will try it but works pretty good for composite. The resistor values aren't common sizes, this is what I measured from the 4 pots that I then replaced with the resistors, I just mixed and matched to get values within a couple ohms. I really didn't see any improvement when I ran the outputs through a transistor for amplification and I have no idea if this conforms to composite standards (I'm sure it doesn't)

 

the picture posted in that post is nearly identical to what I did to my JR, its INTENSE on a CRT, but just about perfect on LCD

[Starfire]

Yes I'm using a modern LCD TV, though if you clip that one resistor that I mention for color that will tone down the intensity. I also imagine if you multiplied the values by 10 you would tone it done, it's the ratio of the resistors that are important. Still haven't tested for S-video but will.

 

Merry Christmas!

Edited December 25, 2013 by Starfire

[Starfire]

Well it works for s-video, but there are vertical bars. It comes from the chroma signal but I'm not familiar with how the signal is generated. Perfect for composite though so maybe it could be an artifact of a modern LCD.