^ I don't happen to have a 103 cabled up at this point, but I just checked with a 105D and I'm having no problem sending 480i to my LG E6 when playing an SD-DVD disc using Source Direct.
So let's go back to basics here:
What firmware do you have in your 103? Check Setup > Device Setup > Firmware Information. The Main firmware version number should end 83-1226. If you have some other firmware in there it is time to update. Instructions are on OPPO's Support page for the firmware, here:
Next, I want to confirm that when testing this you are playing a regular, commercially sold, SD-DVD shiny disc. Not some sort of media file or user produced disc. Right?
Next go into your LG E6, to the bottom of its General settings and confirm that Home/Store Mode is set to HOME MODE.
If the above is all correct, then the next step would be to do a Reset Factory Defaults on the player and try again with Source Direct.
If that still does not get you 480i to the LG E6 then you should get in touch with OPPO Tech Support so they can help you sort this out.