Hi pcrock, thanks for the reply.
My european Atari Jr. got a UM6526P1 8850S chip. However, modifying it to NTSC will change the palette and make the console behave just like our brazilian Ataris, right? If that is true, it will defeat the whole purpose of using an european Atari. There is a handful of games that are only released in Europe or their 50 Hz counterparts are much more cheaper than the 60 Hz ones. That is the main reason I've got this console, to play european games.
I don't get it, PAL-B and PAL-N are the same color TV system. The difference between them lies only in the color subcarrier frequency while using composite video. That is why TVs in South America often detect european PAL as PAL-N and, as a consequence of that, they fail to retrieve any color from the signal. It should be easy to convert a PAL-B console to the PAL-N system, but I still had no luck trying to do it. ☹️