S/PDIF connectors and making your own MB S/PDIF connector

[redwudz]

This is a bit hard to see, but I have a S/PDIF coaxial adapter plugged into this MB. The red box shows the adapter. The PCI slot connector is laying there. The green is the MB coaxial S/PDIF connection. The yellow is the optical S/PDIF connection. Both have exactly the same signal.





This is one of the factory S/PDIF coaxial and optical PCI backplane adapters:



You can also use an external optical to coaxial adapter if you just have optical out and need coaxial. I use this one on a WDTV box to get coaxial output: http://www.monoprice.com/products/product.asp?c_id=104&cp_id=10423&cs_id=1042302&p_id=...seq=1&format=2

I have also made my own adapters with a blank PCI slot plate with a RCA jack installed. I used an old CD audio cable and just changed the pins around. You only need two wires for coaxial audio, the red and black. The third pin on the MB S/PDIF connector is 5VDC power and isn't needed. It's used to power a coaxial>optical converter if you need optical S/PDIF output.


A short guide to making your own S/PDIF coaxial audio connector for your motherboard:

First check your motherboard manual to see if you have a S/PDIF output connector. You may also have a S/PDIF input connector. The output connector is usually labeled 'SPDIFO', the 'O' being for output. The input S/PDIF connector is usually labeled 'SPDIFIN'. Pay attention to the orientation of the connector. You only need two leads, the signal lead and the ground lead. Don't use or attach the +5VDC lead if you are just wanting coaxial audio. Most modern MBs have at least a S/PDIF output connection. If you want S/PDIF optical instead, then you generally need a factory adapter, or I believe Monoprice carries external coaxial>optical converters also.

This is from the MB manual for a ECS R485M motherboard showing the S/PDIF output connector.




This is the pin designation. Pin 1 is the signal and Pin 4 is the ground. That's the only pins you need to use.




These are the parts needed: A blank PCI backplane insert. Yours may vary. A CD to MB audio cable. These aren't used for DVD drives, so there are a lot of them around. You can also use other connectors that have a 0.1" pin spacing. PC case to MB front panel connectors will also work if you have an old case. Last is a RCA phono jack. Most electronic parts stores should have this. Shielded wires aren't needed for this as the run is short and there is a ground wire within the cable. Otherwise with individual wires, twist the wires together. Since the signal is digital, it's mostly immune to RF interference.




What the MB S/PDIF connector looks like.




The backplane insert drilled with a 1/4" hole.




The RCA phono jack attached. Bend up the ground tab a bit before tightening the jack and it's easier to access for soldering. I also used a lockwasher to keep it from loosening, but not required.




The CD cable and connectors. I cut one end off at the connector and cut the white wire off on both ends. If you use a safety pin, you can gently lift the plastic retainer flap and pull out the connector pins to arrange them to your motherboard connector. Try not to stab your finger.




Two pins removed and one to go. As mentioned, I will cut off the white wire and connector.




The connector pins plugged into the correct sockets. They just slide in and the plastic retainer should hold them. Make sure they are oriented the same was as when they were removed.




The backplane ready to solder to. I removed about a 1/8" insulation on both wires and tinned them with solder.




The wires soldered to the RCA jack. I also used a bit of hot glue to hold the wires in place so they are less likely to break if moved around a lot.




The connector plugged into the S/PDIF MB connector and ready to go.

[deltron_fetus]

Great work, where could I possibly buy this?

[usually_quiet]

Great work, where could I possibly buy this?

Look for "SPDIF Optical and RCA Out Plate Cable Bracket" on Amazon.com.au or ebay.com.au

This is a Gigabyte version
http://www.ebay.com.au/itm/Gigabyte-12CR1-1SPOUT-12-SPDIF-Optical-Output-Audio-Cable-K...9341013&_uhb=1

[deltron_fetus]

thanks for your help, I was missing a couple of key words in ebay search!

[redwudz]

I'm still using this home-made S/PDIF adapter with my latest motherboard. The MB has a optical output, but no coaxial and my audio switcher needs a coaxial input. Most motherboards do still have a S/PDIF header.

[benny59]

great, but what and how should I do it if I want an S/PDIF input instead of output? My MB has three pins on motherboard Power, SPDIFI and Ground. What should I solder to the RCS connector?

[redwudz]

Motherboards that have a S/PDIF in will list it in the motherboard manual. If they don't, not much chance of connecting to it, even if there are solder pads on the motherboard. The BIOS and correct drivers would have to be installed, and that's not likely if there aren't headers.

And welcome to our forums. There may be some way to add a S/PDIF input (Digital input) to a PC, but others here would have to make a suggestion.

A few of my older MBs do have a S/PDIF in header, but it's not common. This is what a S/DIF header looks like on one of my MBs.
The 5VDC on the connector is to run a optical (IR Diode) output for optical out, usually TosLink :

[fritzi93]

The bump up on this thread was very timely for me, as the optical out on my Asus mobo died just today.

I'd forgotten there was an adapter like this:

http://www.amazon.com/SPDIF-RCA-Plate-Cable-Bracket/dp/B0035J9Z7W

I checked the pin-outs on my mobo and it looks like the above will do the trick without modification. I could have made one (and used coax instead of optical) using this excellent guide, as I have a soldering iron (2 actually), blank plates, and spare CD audio cables. All I am missing is the RCA jack. Too lazy to do it though when I can get one for a measly $13 bucks.

Thanks redwudz.

[redwudz]

That particular circuit board is somewhat universal to most motherboard S/PDIF output connectors. You just need the 5VDC feed and the S/PDIF out connection on the MB. The coaxial and optical outputs on the motherboard are the same specifications, the optical is just converted to light via a infrared diode.

[eadmaster]

can i do one by cutting an old composite video cable and 2 breadboard wires?

I am sure the breadboard wires will fit because i've already used them to wire a speaker, but i am not sure about the composite cable...

[redwudz]

Most all PC motherboards use standard industry .1" spaced connections for S/PDIF and other similar connections, so yes, those would work. I got my wires from a junked computer.

Since the signal is digital and inside the computer, you don't really need a shielded cable, but I would twist the two leads together just to reduce the chance of interference and to make them look tidy. The wires I used for my adapter were not coaxial or shielded.

[fritzi93]

I went ahead and made one just like in the guide, while waiting for my mobo warranty replacement. (Other things started to go haywire on the mobo as well).

Works like a charm on the new mobo. I never bothered to put in the spdif adapter I ordered from Amazon.

Finally some vindication for saving stuff like backplate inserts and CD cables, etc, from junked computers!

Thanks again.

[ahhaa]

I'm still looking at your motherboard and drooling..:]

[coax_toaster]

Warning: Wrong wiring on your home-made S/PDIF header -> coaxial cable adapter can blow your DAC

I blew my FiiO D3 (D03K) last night. As far as I can tell, because the polarity the adapter I built must have been reversed. My Asus B350-M has an S/PDIF header the same as in the pictures shown above (same board location too), except it has Pin-Blank-Pin-Pin instead of Pin-Pin-Blank-Pin. I wired my adapter to match what the pictures show but flipped. After I plugged it in and started up my system I didn't get any sound, then things smelled horrible. By the time I realized what it was a couple surface mount resistors on the D3 were completely burned off. I wouldn't have thought there to be so much power on the S/PDIF pins, but lesson learned. I should have used a multimeter to verify the pins.
[Attachment 61089 - Click to enlarge]