Sega Saturn SPDIF mod

[atohmdiy]

Hello,
I bought a japanese saturn on ebay and i made some mod, psu + fram + spdif. I receive a mode today so i finally try it. I use a sony bvm and i made a all-in-one (dac + amp + two speakers) for sound with some elements from previous project. The dac i use only has two spdif input, so i use one for the saturn and one for my Mister...

Anyway, fram, psu and the mode are working fine, but not the spdif. I spend the last hours trying to understand why it is not working, and it's beyond my skill. I use this i2s to spdif interface :

https://www.audiophonics.fr/en/diy-inte ... 12559.html

This thing has a terminal block for a 5v DC plus the i2s input. Strangely there is a DATA 1 and DATA 2 on the i2s input, i don't know why.

My saturn is a model 2 japanese with a TDA1386T dac. I get the 5v DC from the pin 9 - 10, i check with a multimeter and it's fine. For the i2s signal i connect this way :

MCK to pin pin 12 (sysclk)
BCK to pin 4 BCK
LE to pin 5 (word select input)
DATA to pin 6 DATA (i2s Data)

For the GRD, two cable connected to the pin 9 (digital ground) go the the i2s grd connector and DC terminal block ( - in the photo).

The spdif kit power on, tension is good on the dc terminal. I connect it with toslkink and there is light, but no sound. I check the tension in the i2s input, i get between 3.2v and 1.7v depending on the input, so there is no problem with the connection.

Any idea ?

[cr4zymanz0r]

I'm not familiar with that board and I don't really understand the fine details of what all is required. However, I have successfully used this board for digital audio on my model 1 Saturn https://oshpark.com/shared_projects/aCufR9Yg

[atohmdiy]

Yes i should have go for something like this, but as i had to make an order at audiophonics so i thought it saved some shipping...
I hate these chinese board because audiophonics do not give a s*** to give correct technical information and the technical service don't know much better. I have problem in the past and now it's the same story, i won't even ask audiophonics it's a pure wate of time, and every info i could find on these board are of course in chinese.

As you can see this board has a i2s input and output, plus 2x spdif output (toslink and rca / bnc). I start to think there is a way to choose between the i2s output and spdif outputs. I check the tension on the i2s output and there is the same voltage as the i2s input, so the i2s out is active. There is no sign of jumper in the front of the board, but in the backside there is an IC close to the i2s input, and two resistor that can be put in different position.

https://zupimages.net/up/20/32/5idx.jpg

[FBX]

I would suggest either giving citrus3000psi's mod board a try (it's on OSH Park and I also use it in my PS1), or designing your own using the CS8406 in hardware mode.

[atohmdiy]

I ask in diyaudio and it appear the saturn do not output standard i2s, even if it's connection are the same. So my spdif board, that have a fpga to handle the input, surely do not recognize the format, so it's useless
I order the board at OSH Park, at least it is known to work. Thank you for the tip.

[atohmdiy]

Hello,

I finish the mod, i order a "pep audio 1.2" board from citrus3000psi and finish assemble and integrate it. It doesn't work

I am pretty sure the board is well assembled, i check the tension, voltage are great for both the +5v power supply and i2s line. I have hard time solder the very small ic, but i am pretty sure it is good as i check the output. The toshiba ic receive the digital audio, but i get no voltage at its output (pin 15), i should get 0.5v, but nothing here. My tc9231n could be a fake, or i miss something. I suspect the 3 pin on the middle with "sat" on top and "ps1" on the bot to not to be a jumper like i thought, i connect the middle pin to the saturn pin. Maybe it is not that ? It's a pain that there is no explanation or schematic

[FBX]

One thing I wanted to give a heads-up on with Dan's board on OSH Park is sometimes a thin ground pour will snake in front of the wire pads and cause shorts. I had to take a hobby knife and carve the area highlighted in red off to prevent shorts:

[atohmdiy]

Thank you for your answer, i will investigate my board.

Can you confirm that the middle pin need to be short with the "sat" pin. It's logical but i prefer to be sure.

Regards

[dokterfreddy]

Where you able to solve the issue. Because I have the exact same issue with the 1.2 board. I allready performed this mod on a PS1. And this works perfectly. But the on the Saturn I can’ t get it to work.

I have a JPN VA3 board.