Open Source Extron Phoenix Audio Adapter PCBs

I recently bought an Extron Crosspoint 12×4 RGBHV audio/video switch. I was quickly dissappointed by the non-standard audio connectors which are on this device. If you’re a chump like RetroRGB you can strip a bunch of female RCA cables and use 3.5mm Phoenix Screw Terminal connector to interface to the Extron’s audio inputs and outputs. But I’m no chump – I needed a real solution!

If you can’t be bothered to read this very short blog post, the source for the PCB is here:

https://github.com/db-electronics/phoenix-audio-adapter-kicad

Finding a Stacked RCA Jack

First I needed to find a stacked RCA stereo jack which would fit in the width of the 5pos Phoenix Connector. A quick tour on Digikey yield this resulted which seemed perfect for the job:

 

https://www.digikey.ca/products/en?keywords=CP-1435-ND

Custom PCB

Next, I needed a way interface the CP-1435-ND RCA jack connector the 5pos Phoenix Connector without any wire stripping. I decided a custom PCB with 5 fingers which could be inserted in the Phoenix Connector’s screw terminals would be the best solution. I fired up KiCad and whipped up this simple PCB in a few minutes. I removed the soldermask from each finger and added copper pads on both top and bottom layers for each finger. If need be, I can tin those copper pads to improve the connection between this and Phoenix’s screw terminal.

Select a PCB Factory

I was a bit worried about the small size of the each finger on this PCB. I’ve ordered PCBs from factories in the past where they would definitely mess this up; such as dirtypcbs. I contacted the factory to make sure their tooling could handle this design. I went with Smart-Prototyping, I’ve had very good success with them in the past.

Wait a Few Weeks…

… hardware dev is long…

Test The Final Product

I am very pleased with the final product. I was worried about the PCB not being very sturdy in the Phoenix Connector – turns out with 5 screws holding it down it is very tight and reliable. I also tested with both tinned and untinned fingers, there seems to be no difference between the two – therefore tinning the fingers is probably not necessary.

As can be clearly seen, these are a match made in heaven for HDRetrovision YPbPr cables.

Source and License

This extremely simple design is licensed under the CERN OHL v.1.2. The source and gerbers can be found on Github.

https://github.com/db-electronics/phoenix-audio-adapter-kicad

René

Electronics engineer and retrogaming fanatic!

16 thoughts on “Open Source Extron Phoenix Audio Adapter PCBs

  • April 24, 2018 at 05:50
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    I love this! I hope some game company takes advantage of this gift and puts them into production.

    Reply
  • April 25, 2018 at 10:52
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    Hey, saw your interview on Bobs weekly roundup, I’d be interested in buying 5-10 of these if you make them. Thanks!

    Reply
  • April 25, 2018 at 13:06
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    Please make these

    Reply
  • April 25, 2018 at 13:43
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    Hi, Rene. Do you have a vendor that you would recommend to produce these? As you spoke about in the RetroRGB weekly update, the “fingers” are a problem for the vendors that I have contacted.

    Reply
  • April 25, 2018 at 16:05
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    The Extron documentation has different wiring for unbalanced audio inputs and outputs. You seems to have followed the input wiring. What about the outputs?

    Reply
    • April 25, 2018 at 17:54
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      Ok I shouldn’t connect the -ve terminals to GND on the outputs, this still works correctly on my setup right now though. I’ll have to find the output circuit schematic to see exactly what’s going on. For the time being I could always cut the GND signals for outputs.

      Reply
      • April 25, 2018 at 18:32
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        Rene,
        The connectors can be wired for in/out by adding a couple of resistors. This is how Extron wires their CSR-6 connector: https://www.extron.com/download/files/userman/csm6csr6-man-c.pdf
        They refused to tell me the resistor value but I saw an old AVSforum post saying to use 1k resistors. I did this with a few cables I made and it’s working fine for input/output.

        Reply
        • April 25, 2018 at 19:07
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          I figure I’ll just make another PCB which will be the output version. I understand how adding the resistors makes it universal but that’s added complexity for a board that will mostly be used an input.

          Reply
  • April 25, 2018 at 18:25
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    This looks great 🙂 I’ll buy 12 for input and 8 for output. Extron CrossPoint 300 128 HVA.

    Reply
  • May 17, 2018 at 08:00
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    The Stacked RCA Jack is too tall for my Extron CrossPoint 300 128 HVA.
    – The Stacked RCA Jack Main housing hight: 27.4mm.
    – Open space between the audio adapter pcb and the BNC connectors: 20.3mm.

    https://photos.app.goo.gl/WXkoNfEdkii88Vjd2

    Reply
  • October 3, 2018 at 13:59
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    Wouldn’t the stess of the wires pulling down on these eventually snap the board?

    Reply

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