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

Good day!

I have an Atari 2600 4-Switch Darth Vader NTSC PCB CO15519 REV 16 (C) 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.

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/r...Atari 2600 Darth Vader 4-Switch?sort=3&page=1

Any help will be highly appreciated
Thanks in advance

 

Your television is capable of RGB NTSC 4.43 colour via SCART. It obviously can't do it over composite. You'll need an NTSC to PAL converter, or replace the video crystal.

 

The epoxy box sure look like a NTSC to PAL trascoder circuit. That kind of modification don't change the video rate to 50Hz though. And I believe some TVs might be stupid (as in cheap to do video system detection as cheap as possible) and detect NTSC signal through vertical frequency.

I suggest you undo all the mods, make it factory original NTSC and then apply a video output mod. I am sure any modern TV can accept a NTSC signal.

My country (Brazil) uses 60hz PAL and my Atari console is identical to yours. It had a transcoder module and the clock crystal was changed from the proper 3.57595Mhz for NTSC into Brazil's M-PAL crystal (3.575611Mhz). I undid all changes and it gave me good NTSC colors.

 

[FONT=&quot]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 appeared!
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 and there are some vertical jail bars (Like vertical scanlines) throughout the screen.

Thanks for the very interesting info! Yes I suspected that the epoxy box might be some kind of NTSC to PAL converter, but I didn't bother removing it.
Now that you mentioned it, do you think that removing it, there will be any difference in the colors and vertical lines?[/FONT]

 

Removing it would make the thing operate in NTSC again. But you will need to replace the color crystal with the one which is right for NTSC.

I don't know how the epoxy box works though it could have a PAL crystal inside.

Btw when I modded my ATARI for composite I used a much simpler circuitry. I just removed a resistor and added an secondary transistor amplifier:


That after coming into the realization that the "original" internet method of disassembling half of the ATARI video output circuit was stupid I put all the parts back on their original positions and all it took was remove R222, C215 and move R209 to bias the BASE pin of the new transistor circuit...