TOSLINK/SPDIF output board (project)

[kgallen]

Twin TOSLINK plus coax output board.

 

Transformer isolated coax output based on Sony MDS-E10 ‘pro’ output stage. The pulse transformer is the most expensive part by far (about 4GBP) but the PCB is padded out for a couple of options to mitigate against availability issues. 

 

This project is partially @BearBoy’s fault 😆👍
 

I subsequently found the part Sony use for the Coax RCA connector so I will redesign the PCB. I also missed one capacitor in the coax circuit. No real consequence but I’m a stickler for detail…

 

I originally designed this for my MXD-D4 to provide TOSLINK output from both the CD and MD sections. However with @BearBoy’s input I added the coax output and selection jumpers so it can be used with an MD-only machine and thus add twin TOSLINK and coax outputs.

 

Just a DIP 74HCU04 IC goes in the socket. 

 

[BearBoy]

Wow. That looks like a cracking piece of work, @kgallen. Really professional looking.

 

Will that work on any Sony deck with a single digital output?

 

And apologies if I was responsible for sending you down this particular rabbit hole 😲  😆

 

[kgallen]

It has to wire into a couple of points on the main PCB (or stuffed into the ribbon cable socket before @sfbp pulls me up on that one!). The machine doesn’t need to have any digital I/O on the back panel already. 

 

I’m only really familiar with the Sony machines and it should work with any as they use the SPDIF protocol natively internally. Otherwise this PCB has the interface drive circuits so doesn’t rely on the main board having any digital outputs already. 

[BearBoy]

Nice! As second hand deck prices seemingly continue to rise, it would be useful for closing the gap between the budget models (MDS-JE4xx/3xx) and their ever more expensive brethren...

[sfbp]

11 hours ago, BearBoy said:

Wow. That looks like a cracking piece of work, @kgallen. Really professional looking.

 

Will that work on any Sony deck with a single digital output?

 

And apologies if I was responsible for sending you down this particular rabbit hole 😲  😆

 

I think I may be the one that (indirectly) caused this. I am the proud possessor of its previous incarnation which is a simple 1->2 Toslink splitter, designed and built by Kevin.

The idea of adding the direct (coax) out is great, too. But I am happy with my gizmo regardless.

[Richard]

This looks fantastic Kevin - really neat! I wonder what the chances are of somehow being able to retrofit one of these into one of the Onkyo Hi-MD decks maybe 🤔

[kgallen]

Sorry I didn't realise the photos were so big - shrunk them now I've managed to get on the site via a PC and Firefox (rather than on a phone).

 

7 hours ago, sfbp said:

I think I may be the one that (indirectly) caused this. I am the proud possessor of its previous incarnation which is a simple 1->2 Toslink splitter

Indeed Stephen, that was the first project that made me dig into the TOSLINK circuits. This new project was originally pretty much that splitter without the input receiver and wired into the machine, but then @BearBoy and myself started discussing a coax output, so I looked into that and added one.

 

45 minutes ago, Richard said:

This looks fantastic Kevin - really neat! I wonder what the chances are of somehow being able to retrofit one of these into one of the Onkyo Hi-MD decks maybe 🤔

I'm not happy with the coax RCA socket on this v1 PCB since it doesn't have any mechanical support. The one Sony use has a screw that can be used to secure it to the case for mechanical support. The one I have used relies on the solder joints to the PCB (although I did pad out a large area of copper for mechanical support). Subsequent to sending off the PCB design for manufacture, I finally tracked down the part that Sony use (attached) and found someone on eBay selling some, albeit with the black insulator rather than the usual gold/orange for SPDIF. None of the mainstream suppliers here (RS, CPC, Farnell) stock this component. I think Mouser might list the range but I didn't want to buy a thousand or have one shipped from the US at great expense. Anyway I'm in the process of redesigning the PCB for that (larger) part, but I haven't fully tested this v1 design yet, so won't order a v2 design until that's complete.

 

Regardless, this board could actually be used sub-equipped as a single or dual TOSLINK output, and as long as your machine has SPDIF internally (which it will if it uses the Sony CXD DSP chips) and 0V and +5V then it can be fitted. The electronics is easy, it's the taking apart and drilling the back panel which is the hardest part.

 

I have some spare v1 bare PCBs if anyone wants one to play with. I'll let you know how I get on with the v2 and if anyone is interested, give me a shout. You lot might get a little prezzie anyway for your ongoing help and encouragement!

 

I suppose what I should do is do an "all features" PCB that can be a splitter or fitted internally to a machine with whatever combination of TOSLINK/Coax outputs you want. I guess this could end up being a bit over-engineered because the splitter needs a power supply and an input circuit whereas the output board doesn't require either.

 

However I guess the point is I know about all of the building blocks so if you fancy something, drops some ideas around. After all these little projects come about from suggestions/ideas/threads on here! 🙂

 

Boy, it's great to be back...

pjras1x1s_x_series_cd.pdf

[kgallen]

PCB v1 info for anyone who cares (schematic, pictures of PCB, Gerber files).

 

ETA: C30, C33 should be 100nF (0.1uF) NOT 100pf as on the schematic/BOM.

 

SPDIF Output.pdf PCB_PCB_SPDIF Output_Top.pdf PCB_PCB_SPDIF Output_Bottom.pdf PCB_PCB_SPDIF Output_Silk.pdf Gerber_PCB_SPDIF Output.zip

[EdinElk]

On 1/14/2022 at 7:35 PM, kgallen said:

It has to wire into a couple of points on the main PCB (or stuffed into the ribbon cable socket before @sfbp pulls me up on that one!). The machine doesn’t need to have any digital I/O on the back panel already. 

 

I’m only really familiar with the Sony machines and it should work with any as they use the SPDIF protocol natively internally. Otherwise this PCB has the interface drive circuits so doesn’t rely on the main board having any digital outputs already. 

Onkyo md 133 with sony kmk 400AAA and avaliable DOUT

[kgallen]

Hi @EdinElk, do you have a photo of the other side of the PCB?

 

Also I probably have some of my project PCBs (above) lying around - they are bare, unpopulated, you'd have to buy and solder the components of interest (all at your own risk!) If any use and you pay postage from the UK, then shout up.

 

Kevin

[EdinElk]

7 hours ago, kgallen said:

Hi @EdinElk, do you have a photo of the other side of the PCB?

 

Also I probably have some of my project PCBs (above) lying around - they are bare, unpopulated, you'd have to buy and solder the components of interest (all at your own risk!) If any use and you pay postage from the UK, then shout up.

 

Kevin

Hi Kevin,

Thanks, I'd be interested buying two-three PCB plus details or soldered boards, for testing toslink out from any of sony/onkyo Hi-MD players. I am near Coventry, so delivery is all right.

Could you confirm you have used with success only 'dout' and 'dground' Sony DSP pin connections to your board, getting spdif out?

Have you activated the spdif out in the service menu or via md desk uart?

 

Cheers,

Dim

 

[kgallen]

16 minutes ago, EdinElk said:

Thanks, I'd be interested buying two-three PCB plus details or soldered boards, for testing toslink out from any of sony/onkyo Hi-MD players. I am near Coventry, so delivery is all right.

Could you confirm you have used with success only 'dout' and 'dground' Sony DSP pin connections to your board, getting spdif out?

Have you activated spdid out in the service menu or via md desk uart?

Hi Dim.

 

(ETA I should have looked at your photo in detail first - I didn't!)

 

You don't have to buy them, you can have them for free. I probably got 10 in the PCB order and I've built one as the prototype so the others are sitting around.

 

You other question is related to a comment I've just made on the other thread. We need an SPDIF signal, not separate DAC/ADC clock and data, which is what I think we've got. The Sony decks I've looked at have the digital data in both formats on different pins of the DSP, so probably as the Onkyo uses a Sony DSP, the signal will be there, but I don't know if it's accessible.

 

So in answer to this question:

16 minutes ago, EdinElk said:

Could you confirm you have used with success only 'dout' and 'dground' Sony DSP pin connections to your board, getting spdif out?

then no, my board can't work with the clock plus data serial interface seen on e.g. the AK4524 DAC/ADC, my board is just a buffer and electrical interface where the deck already has SPDIF available, which as above is quite usual with the Sony DSPs, but possibly not guaranteed. This Onkyo probably uses the CXD2687 which is what I believe is used in the MZ-NH1 portable. It includes the integrated ARM controller. Since it's a fully integrated IC for a portable unit, quite possibly they didn't put an SPDIF interface on it? I'm not familiar enough with the CXD2687 to know off the top of my head. There does seem to be a Service Manual for the MZ-NH1 with schematics so with some study maybe the above questions could be answered.

 

I originally designed my board for an MXD-D4 CD/MD combo deck which uses SPDIF natively internally. The Philips DAC they use has an SPDIF interface which takes SPDIF from the CD and MD sections. This is generally different to the MD decks I've looked at which use e.g. the AK4524 DAC/ADC which has a clock plus data serial interface along the lines of the test points you've flagged on your photo. But then this decks almost always already have either TOSLINK or Coax SPDIF out, so piggy-backing on that to provide more outputs is easy.

 

16 minutes ago, EdinElk said:

Have you activated spdid out in the service menu or via md desk uart?

That wasn't necessary - the deck is already using SPDIF natively internally, so the signals are just grabbed from appropriate vias or component pads on the main PCB.

 

So in summary, more study of the Onkyo design is required to know how easy it is to add TOSLINK/Coax SPDIF out to these machines. Gut feel is if the DSP provides the output it should be perfectly straightforward. If it doesn't then it's a bit of a non-starter as a serial-to-SPDIF format conversion would be required.

 

Hope that helps... a little!

 

Regards,

Kevin

 

 

 

 

 

[kgallen]

I've finally gotten around to building and testing my v1.1 PCB of this project (yes, I know, it's been a while...). This includes the coaxial connector that Sony uses that has the chassis screw point and also includes some circuit updates to the coax/SPDIF circuit to match the MDS-E10 circuit. The optical and coax connectors are on the pitch that Sony uses on their machines (or at least the one I measured!). Sorry my photos aren't up to @Richard's standard. And thanks to @sfbp and @BearBoy for sending me down this rabbit hole! @EdinElk, thanks for hanging in there...