Unfortunately, without a modification, the 3DO only outputs 480i and does not output RGB. It does output S-Video though and good mods are available for certain models.
Info / Mods:
3DO’s that use a specific chip (the VT chip) can be modded both for RGB and 240p! 3DO’s that use the “Bt9101” chip can be modded for RGB, but will still only output 480i. There is one motherboard / chip revision of the 3DO that can’t be modded for either. For more information on 480i and 240p, please see the 240p page.
Mod your 3DO for 240p output
RGB + 240p Mod (Compatible with all chips except “Anvil”):
SPDIF / TOSLINK Mod (only certain models).
RGB Mod Technical Info & Service Manuals:
Taijigamer2 emailed me the service manuals for the FZ-1 and the FZ-10!!!
Original RGB Mod:
Here’s a diagram of the actual RGB mod, in case you’d like to try and make your own circuit (experts-only!):. As an FYI, I believe this was the first person to accomplish a 3DO RGB mod: http://www.digitpress.com/forum/showthread.php?81651-3do-rgb-mod-done-and-working!-pictures-included!&highlight=acem77
If you’d like digital audio output, you can try this mod: https://assemblergames.com/threads/3do-fz-10-toslink.58126/
The 3DO’s S-Video output is excellent and casual users will be more than happy with it.
All fans of the 3DO should look into the 240p/480i switch mod, as all games except FMV’s look much better in 240p…and even FMV’s are debatable.
At the moment, the most reliable way to get the 240p mod is via Dan’s RGB mod, so if you really like the 3DO, that’s by far the best solution for your console.