Pictures RCA Nuon Player PCB Pictures And Controller Port Hacking

[cubanismo]

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:

 

[cubanismo]

And just for fun, here are some pics of the outside of the unit:











To open her up, remove the two side screws seen on the left and right views, and the 5 top and side screws on the back panel. Be VERY careful taking these screws out: They are quite soft and the heads strip easily! I had to resort to pliers to get one out. After all the screws are removed, gently lift the outer case up from the back to about a 45-60 degree angle, then work it out from under the lip of the front panel. Overall, similar process to disassembling a Toshiba SD-2300.

This particular unit is a bit dirty, so hopefully next time I open it up I'll have a little more time and can give the case a good cleaning. If you want any more pics or different angles or anything, let me know.

 

[The Helper]

This is a very interesting project! I cannot wait to see what comes out of it. Especially if furthers are understanding of the NUON port protocols to advance our knowledge on how to use the controller port to upload game code, Every NUON model should have the ability to have a controller port even if it was not built in!

 

[cubanismo]

I have made major updates to the RCA-DRC300n/RCA-DRC480n joystick port parts list spreadsheet. All the parts have been identified, most by mapping them to equivalent parts on the Samsung N504/N505 schematics (These come with the N505/N504 service manual). I've also dug up DigiKey part numbers for all of them, and will be placing an order soon. Some caveats:

• The zener diode (ZJ2) has no direct equivalent on the Samsung units. I picked a random Zener diode with a 5.6 breakdown voltage on the theory it's serving as overvoltage protection for the 5V rail it sits on.
• There is a strange issue with the RCA PCB layout: It connects the 3.3V rail into the 5V power supply transistor network at one point, where the N50x clearly connect to the 5V rail. On the pictures above, you can see this as the trace between one side of CJ1 and RJ28. If needed, that trace could be cut and replaced with a bit of wire connecting the trace shared by CJ9 and LJ10 with the pad nearest it on RJ28. However, I'm going to leave it as is for now on the assumption the people who designed these boards know about a million times more about circuit design than me.
• I didn't list a part for J2, the header used to connect the actual nuon ports/controller ports. My plan is to wire in some standard 4-pin ieee1394 firewire female ports for now using whatever parts I can dig up for testing, and test with the USB adapter or Aries64 adapter, both of which have standard 4-pin firewire male connectors anyway. If things work, I can look into building a little PCB to house the ports and sourcing a good 6-ping connector to go with whatever 6-pin cable I end up using for that.

 

[cubanismo]

And for posterity, some pictures of the RCA DRC300n internals. This unit was a bit easier to disassemble than the DRC480n, but the instructions are roughly the same except it has two screws on each side instead of one, presumably to compensate for having two fewer screws on the rear. The little lip that holds the casing snug to the faceplate on top is also less "sticky" on this one, so it popped off much more easily.

Beginning this time with an overhead view of the unit with its lid removed:



Then a closeup of the power board:



The best I could get of the front-panel PCB without removing it:



Then the main PCB and the output PCB:



Note these look identical to the DRC480n boards, except they lack the daughterboard. I suspect that entire daughterboard is just to enable the DRC480n's progressive scan output. Must have cost a fortune to add all that in just to get progressive scan support.

Here's a closeup of the joystick/controller port circuitry, identical to the DRC480n's of course:



and a closeup of the A/V support circuits (Not sure why I took this one, but here it is):



After this, given how much easier it was to get at things in here compared to the 480n with its daughterboard craziness, I was convinced this was the right unit to tackle modding first, so I disconnected the main PCB and removed it. It took a lot of careful prodding on some of those connectors, as they had gotten pretty crusty and stiff over the years and I was very afraid I was going to break one, but they all made it out in good shape in the end. Here's the isolated PCB, front and back:

 

[cubanismo]

And again just for fun, some shots of the case:











Click to enlarge of course. Enjoy!

 

[cubanismo]

Looks like I never followed up here with the bad news: The build did not succeed. I didn't ruin the unit or anything, but the controller ports do not work. There are two issues:

• The voltage output of the power regulator-looking part of the circuit is too low. I looked back at some old Discord records, and it looks like it showed up as 4.3 volts without a load, but dropped to 1.5 volts "loaded" when connected to the Songbird N64 controller adapter.
• Even when I rerouted things so that the RCA unit's 5V rail was feeding directly into the controller port and the Songbird controller adapter did power up, the Nuon didn't enumerate any controllers. I verified on my oscilloscope that even though there is a clock signal generated, no signals are sent over the data line from the Nuon.

This needs more investigation. I don't think I probed anything upstream of the actual controller port, so it's possible I made a mistake and didn't wire up the encoder/decoder chip that splits the signals between ports 1 and 2 properly, or something of that nature, but kind of unlikely I think. I suspect the BIOS code to handle controller init is just missing. I tried manually banging the registers that generate signals here with some quick and dirty code of my own, but still didn't get any signal on the scope. I've taken a break from the project since. The unit still has all the wiring installed, but the case is back on and it's sitting in my cabinet being used as an ordinary DVD player for now. I hope I'll get time to get back to this project eventually.

For now, here are the pictures of the build.

To start, I laid down a key naming all the component slots on my build mat and dropped the corresponding components into their slots so I didn't get things mixed while building:



Then I had to remove all the plugs from the through-hole slots for the through-hole components. This was a huge pain because I don't have one of those desoldering guns with a vacuum pump on it, just one of this little spring-loaded handheld suction things, and of course, only two hands. I rigged the PCB up precariously like this:



And went at it. I mangled one of the ground pads a bit as I had a lot of trouble getting enough heat into it to get the solder to flow out into the gun, but I didn't ruin anything the the point where I actually lifted a pad, thankfully. It took a combination of wicking and suction work in the end, but I got almost all the pads cleaned out really well.



Note I didn't bother removing the solder from the actual controller connector header pads on the bottom of the last two pics. My plan there was to just heat the solder plugs and then stick individual scraps of the other through-hole components through those holes while the solder was hot. That seemed good enough for initial testing purposes.

(To be continued)

 

[cubanismo]

Next I got my trusty solder out, and started with the hardest chip first: The 74HC244 buffer/driver IC:



And then moved on to the tiny resistor pack next to it. In retrospect, it might have been easier to do the resistors first.



Did I say I didn't lift any pads? Well I lied, I did apparently while soldering that IC. So I had to work around that by replacing the relevant trace with a bit of wire:



And then there was the issue of one of the traces just looking wrong, and I wired it up so I could "fix" it later if it was indeed wrong. Note the resistor RJ28 standing on its end above. That's being connected to the 3.3V side of CJ11 here just like it would have been if I soldered it down, but I suspect it's actually supposed to connect to a 5V source somewhere, perhaps on CJ9. That would make the circuit more consistent with those on the N50x boards, and it really looks like the PCB layout person just got their VCC's mixed up here somehow.



Everything else went relatively smoothly. Here's what I did for that controller port header:



(To be continued)

 

[cubanismo]

The rest is just me trimming things to be even and connecting up some test jumper wires to the controller port. The wires connected here correspond to the 5V, ground, and data+clock lines for the first controller port.



These were largely just for my reference so I'd remember which things were connected where after reassembling the unit for testing.

And that's all I've got. I plugged these jumpers into the female side of a firewire PC header cable, and plugged the songbird N64 controller adapter into that, and then spent a night trying to get a signal out of anything, measuring all the lines with my oscilloscope and whatnot. As noted above, nothing doing so far. Sorry to be the bearer of bad news. If you can spot any errors above, please let me know.