Atari 2600 4-Switch NTSC RCA displays Black & White on EURO TV

[retroborg]

Good day!

I have an Atari 2600 4-Switch Darth Vader NTSC PCB CO15519 REV 16 © 1980



On which I performed the Composite RCA AV Mod as described in this Link:

http://retro.mmgn.com/Atari-2600/Forums/Atari-2600-AV-Mod

I specifically used the following components and connected them to 2 RCA Jacks as I did on my other PAL Atari 2600 4-Switch console.

 

"Green TIA Pin 2 (Sync): Direct to video
Yellow TIA Pin 5 (Lum 1): 1k Resistor
Yellow TIA Pin 6 (Lum 2): 220 ohm Resistor
Yellow TIA Pin 7 (Lum 0): 1K Resistor

Red A is for Audio
Blue C is for Color

Pins A and C don’t need any components but you can use\should put a 100p ceramic capacitor on Blue C. Both A and C will then go directly to you RCA jack's."

Everything works fine and the display is much clearer in relation to the RF output without distortions, however both the RF & RCA output only display in black & white on my EURO CRT 21" SONY TV KV-21FQ10 which is more than capable of display in in colour at 60HZ as it suppots PAL-60 and all my other modded consoles play fine on it with color via RGB Scart.

Is this natural because this is an NTSC console, or is it something which I’ve done wrong, or is there a problem with this specific console?
I note that the RF Output displayed in black & white even before I performed the RCA mod, but I thought it would be OK with RCA.

By the way, this specific PCB has this weird circuit enclosed in a huge plastic block like a brick, which is connected on various points on the PCB which I do not recognize their use. I have no idea of its purpose nor have I ever seen anything similar before.

I considered removing it, but decided not to in case it replaces / fixes some defective components or IC on the PCB and has been added as an external fix.

Could this be causing the black & white display?

http://s1356.photobucket.com/user/retroborgx/library/Techs/Atari%202600%20Darth%20Vader%204-Switch?sort=3&page=1

Any help will be highly appreciated
Thanks in advanced

[thecrypticodor]

That's the old Ben Heck mod with 1k fixed resistors in place of 1k potentiometers.

 

 

You just combine your chroma your Luma and sync signals together and you should have composite. You could try pulling chroma directly off of Pin 9 of the TIA and see if that gives you your color. That mod also isn't very good and doesn't work on certain TV's so that could be your problem right there. Honestly I would just rip all of that mess out and just do this mod which is far better than the one you're trying to do.

Edited December 28, 2014 by thecrypticodor

[retroborg]

Thank you for the very helpful info on that alternative RCA Mod!

 

So, it would seem there was a much easier solution. I simply rotated the pot on the PCB a few degrees and the color magically apeared!
With some trial & error I settled at a spot where all my games look ok, with color on my TV. However the colors do look a bit different compared to the other Atari 2600 consoles I've modded.

By the way, does anybody have the slighest idea what that huge block of hard plastic encloses inside and why it's connected on to the PCB?!

I would like to X-Ray it!