As discussed on Discord, it looks like the RCA Nuon DVD players have circuitry on their PCBs for Nuon controller ports. However, all the necessary components are unpopulated. I've acquired a DRC480n and a DRC300n, and am working on figuring out what components are needed to add controller ports to these units. However, I'll likely need some help from some HW experts, as I'm more of a software guy and my experience reverse engineering circuits/components is limited. To that end, I've taken some detailed photos of the DRC480n, especially its PCBs, and will follow up with photos of the DRC300n when I have more daylight available again. I've also started a Google Sheets spreadsheet with a list of unpopulated component IDs on the motherboard and the corresponding part I believe should be used to populate them. That link should give you read+commenter access.
To start off, here's the most relevant part of the PCB (Click for the high-res image):
And viewed from the bottom:
And here's the same area zoomed out a bit:
And just for your enjoyment, here are some shots of the remainder of the PCBs, starting with the whole system opened up:
Close-up of the power supply board:
Close-up of the main PCB and its daughter-board:
And the daughter-board with its shield/heat spreader removed:
To start off, here's the most relevant part of the PCB (Click for the high-res image):
And viewed from the bottom:
And here's the same area zoomed out a bit:
And just for your enjoyment, here are some shots of the remainder of the PCBs, starting with the whole system opened up:
Close-up of the power supply board:
Close-up of the main PCB and its daughter-board:
And the daughter-board with its shield/heat spreader removed: