It all started with a Facebook post on AtariAge group. It promises that with a simple mod you can brighten up your Atari 2600jr picture.
It’s all about changing R31 resistor, that connects to the Pin 6 (LUM2) on the TIA chip. All other versions of 2600 have a 3.3K resistor in this place, except the PAL jr version that has 10k resistor on R31. Changing it to intended resistance should improve the saturation of the picture.
I decided to try it out and while at it, also swap the electrolytic capacitors (just the small one, I didn’t have the 2200uF Axial one).
Comparison
This is probably not the most scientific methodology (should use oscilloscope for that), so you’ll have to trust me with my assessments. The screens were captured with my phone camera on a Samsung smart TV, the artifacts that appear on some of the photos are not visible in person. My Atari 2600jr (PAL) is composite modded with: TFW8b Composite Video Mod. The original output was a bit hazy and washed out, with R31 swapped the colors became a bit more saturated. After recap, the picture became sharper and more vivid.
Conclusion
So at the end of the day is it worth it? In my opinion, if you’re comfortable with the soldering iron, maybe. But still the biggest difference is made with changing the electrolytic capacitors. As with all of my retro machines, this (for me without exception so far) always results in brighter, more saturated and sharper picture on an LCD (I don’t have any experience with the CRT monitors, but I presume the results are the same).
Some references: