Posting this for future reference in case anyone wants to also add AC3 to their CLD D503.

Got the actual board from a member here, ldstl

Kit included:
Board -completly pre wired
RCA Jack
Ground wire with .1uF cap
AC3 RF label for the back
Very detailed instructions

RF Tap point


Voltages you'll need: +5 volts, Ground, -5 volts


Here they are zoomed out:


Basically just 4 wires that go to the LD board (a couple more later for the RCA Jack)
RF
+5 Volts
Ground (0 volts)
-5 volts

Zoomed in. I soldered it poorly just to make everyone feel better lol. Best I could do!



Then the mod board has 2 wires that go to the RCA Jack.
Then run a ground down to a ground screw. You put the .1uF cap between the ground wire and ground screw.


Zip ties to clean it up


The hole I drilled in the back is 3/8". I made a sort of upside down blanket of electrical tape on the inside to catch all the metal shavings. I was really careful with part. Then made a sort of igloo of tape. Didn't get pictures of this. But did catch all the shavings.




Big thank you to ldstl for getting the board to me so fast, including everything, and offering all the support.

Yes, works great! AC3 lock first disc I tried. Very exciting. Tested also regular old analog discs too just to make sure I didn't accidentally break something and no problems, regular analog sounds fine.


Next is to maybe add Toslink (tried and failed so far) and then get 16:9 to work lol

16:9 is an oddball feature that was never supported from what I recall on any Pioneer players.

It appeared on at least one or more Pro-Scan LD player clones and they are literally non-functional unless you own a 16:9 Pro-Scan widescreen CRT TV. My understanding from what Josh Zyber told me years ago is that the function is tied into the S-Video output and it supposedly sends either a DC voltage trigger or data bus command to tell the TV to go into zoom mode (or possibly stretch if the feature was designed for the rare number of titles encoded in 16:9 enhanced) for widescreen CRT TV. So essentially speaking, it’s a useless feature in that you can simply hit zoom or stretch from your TV remote instead.

Also, there is no button on the 503’s remote or front panel so it really is useless to try and implement. The fact that you see it on your FL display is because it exists for cost reasons in respect to making one display that works with all players. You see that a lot on other products as well.

My CLD-2850 had a 16:9 button.
The way it worked was basically like this:
On my TV I had to set format to "AUTO", if I then activated the 16:9 button on the player,
it would switch the TV into 16:9 mode. This of course only makes sense with an
anamorph squeeze disc playing, otherwise it would look rather odd.
Back in the day I tested it with SCART, never tested it with composite.
The European CLD-2850 had no s-video.
A useless feature more or less.

Oh yeah I was mostly joking, but I was thinking it would be cool to get it to just light up for effect. Guessing it was more of a generic panel to save money, not anything they ever planned to implement on this model.

The Toslink I do want to try to get added.

I was reading this thread
[CLD-D503] Adding a digital optical out

But still not sure if I can access the digital signal from the top side of the board without removing the whole audio board and soldering to the chip?

I bought this board below and tried a hooking to a few spots with no success so far.

As I mentioned in that thread awhile back, the only way to tap the digital output is to go directly to the DSP IC. This is the IC and pin that you would need to extract the signal from.....



The difficult part of getting to this chip is that it's on the downward facing side of the main board which means you need to remove the board from the player to get to it. If you feel comfortable doing that, then it shouldn't be difficult. You just need to make sure to find a good opening to get the coax cable back to the top side of the board. Also, I don't think there is a trace that leads out from pin 43 so you might need to solder directly to that very tiny leg (not something I would be comfortable doing myself).

Okay, thanks! I didn't realize from reading that thread if that was definitive or not, or if there was still hope there was some place 43 came through. Good to know and I appreciate you confirming. I had tried following the service manual and thought I found a jumper, but yeah no I was wrong and it didn't work of course. Hard to follow those traces even zoomed in at my age

It's strange from the optical cut out that 5 volt and Ground are connected (I believe from my testing). I wonder why they would have left the trace to 43 unconnected. Oh well.

Yeah, I probably won't attempt it at least for a while. Don't want to risk any damage as my player is working great. Plus I guess I would really only use it for DTS discs and I don't own any anyway. For normal discs RCA is fine since you can switch between digital and analog, I believe you lose that with Toslink/SPDIF so...

AC3 mod was for sure much easier and has really added a lot to the enjoyment of so many of the discs I already have.

Thanks again to ldstl, originally came across his AC3 mod board in this thread: https://forum.lddb.com/viewtopic.php?f=53&t=10326