Need Help Fixing this Rev.14 Atari 2600

[billy_bayou]

Hi everyone!!

I got this little problematic US Atari 2600 rev. 14 (1980) with a glitched screen. Back in the 80s, US Ataris wouldn't work on Brazilian TVs because the US color system wasn't the same as in Brazil (the USA used the NTSC system and Brazil used the PAL-M system). To solve this problem, a small transcoding board had to be installed to make the colors work on Brazilian TVs. A customer requested to revert his Atari back to its original system (NTSC). All I had to do was: remove the transcoding board and replace the crystal (to a 3.579545 MHz one). I did this, but now all I get is a glitched screen with colored vertical bars. I checked every single trace and continuity, cleaned rust on the cartridge slot and IC terminals, and even replaced the IC slots with brand new ones. Nothing seemed to work. My suspicion now lies with the work to revert the color system. As I followed the original schematic from Console5 TechWiki, all components have the same specifications as the schematic. I replaced the components shown in the following shot. Some of them I didn't have with me, so I had to add some resistors in series to make a 'single-one' according to the diagram, just for testing purposes. I measured them to ensure they match the values in the diagram. Now things are getting weird. I also have a Taiwanese Atari with 32 games built-in. I removed its three main ICs (TIA, RIOT, CPU) to put in the US Atari. The problem persists. I think there's something wrong or missing in the color system section, or maybe some modifications were made to the board by technicians to make the transcoder board work (swapped components to different values/specifications? Cut lines? I didn't see any jumpers). Can anyone figure out what's wrong?? Thank you in advance!

[RickR]

I'd check the crystal you replaced. 

[billy_bayou]

4 hours ago, RickR said:

I'd check the crystal you replaced. 

Already done. Still not working...