FBX
Quiz Detective
- Joined
- Aug 7, 2017
- Posts
- 89
So this may be already common knowledge, but after reviewing the schematics floating around on the internet:
https://wiki.neogeodev.org/index.php?title=Schematics
My friend Ste pointed out it cannot have been of the 3-6, even though the stereo audio channels are swapped in the schematic's headphone jack. This is because the composite video and csync pins are not tied together like they are in the 3-6. Additionally, I noted the output caps were set to 100uF and resistors at 68Ohms in the schematic.
Now since we know the 3-3, 3-4, and 3-5 do not have inverted stereo channels, and since the schematic designates 100uF caps and 68 Ohm resistors, my conclusion is that "NEOGEO-2" is actually a schematic for the ultra-rare AES3-2 revision. Indeed this may be a clue as to why the 3-2 is so rare: They caught the channel swap mistake and quickly corrected it in the 3-3 revision. Of course, the only way to know for sure is for someone with an unmodded 3-2 to check the channel orientation. To date though, I've only found one board shot of a 3-2 on the Internet.
Again, my apologies if this is common knowledge by now. I just thought it was quite interesting that the existing AES documentation turns out to be from the absolute rarest of revisions!
https://wiki.neogeodev.org/index.php?title=Schematics
My friend Ste pointed out it cannot have been of the 3-6, even though the stereo audio channels are swapped in the schematic's headphone jack. This is because the composite video and csync pins are not tied together like they are in the 3-6. Additionally, I noted the output caps were set to 100uF and resistors at 68Ohms in the schematic.
Now since we know the 3-3, 3-4, and 3-5 do not have inverted stereo channels, and since the schematic designates 100uF caps and 68 Ohm resistors, my conclusion is that "NEOGEO-2" is actually a schematic for the ultra-rare AES3-2 revision. Indeed this may be a clue as to why the 3-2 is so rare: They caught the channel swap mistake and quickly corrected it in the 3-3 revision. Of course, the only way to know for sure is for someone with an unmodded 3-2 to check the channel orientation. To date though, I've only found one board shot of a 3-2 on the Internet.
Again, my apologies if this is common knowledge by now. I just thought it was quite interesting that the existing AES documentation turns out to be from the absolute rarest of revisions!
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