Sunday, August 27, 2017

DIY RGB Adapter for Sony CRTs with a 34-Pin Multi Input

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RGB from the Genesis on the KV-25XBR via RGB Multi Input

While SCART inputs never showed up on CRTs on American soil, there are still a handful of sets out there that natively support 15kHz analog RGB. Sony in particular released several models in the 80s that sport a 34-pin RGB Multi Input connector. Models that feature the connector include:

  • KV-1311CR
  • KX-1901A / KX-2501A
  • KV-20XBR / KV-25XBR
  • KX-27PS1


The rear panel of the Sony KV-25XBR with an RGB Multi Input

While finding the OEM cable is now pretty much impossible (Sony Part Number PX-34), the port is actually the same size and shape as a standard IDC floppy connector. With just a little knowledge of the pinout of the port we can easily wire up an adapter that will convert from a standard SCART cable into the 34-pin input.


The back of the manual for these sets contains all the needed information about the pins, except for how they're numbered on the connector. Luckily, DanAdamKOF from the Neo-Geo forums was able to figure it out, and I've added it to the image above. There's still one problem left though - Sony's pin numbering isn't the same as standard IDC cables like the floppy! In order to match our SCART lines to the floppy, we'll have to translate it.


Start by cutting your floppy cable in half, and then use the diagram above to figure out which side is pin 1. To find the appropriate wire, just start at the side with pin 1 and count down the wires. I found it easiest to separate the wires using a hobby knife, and then used a lighter to strip the ends. Once you've identified all the wires and prepped them, you're ready to solder it up.

  • Sync - Floppy 9 to SCART 20
  • Sync (Ground) - Floppy 10 to SCART 18
  • Blue - Floppy 15 to SCART 7
  • Blue (Ground) - Floppy 16 to SCART 5
  • Green - Floppy 17 to SCART 11 
  • Green (Ground) - Floppy 18 to SCART 9
  • Red - Floppy 19 to SCART 15
  • Red (Ground) - Floppy 20 to SCART 13
  • Audio Left - Floppy 21 to SCART 6
  • Audio Left (Ground) - Floppy 22 to SCART 4
  • Audio Right - Floppy 29 to SCART 2
  • Audio Right (Ground) - Floppy 30 to SCART 4
  • Audio Select - Floppy 34 to Floppy 1

I've seen people recommending caps, sync strippers and all kinds of other things online, but please know you don't need any of that. The sync input on the KV-25XBR will take anything you throw at it: Composite Video, Csync, and Sync on Luma. Even my GroovyMAME machine with a custom sync circuit works great on it. The one special thing to note is that if you want audio, you will need to connect pin 34 (5V) of your floppy to pin 1 (Audio Select). Other than that, everything just works in my experience.


It's not the most elegant looking adapter, but it works!

A huge thanks again to DanAdamKOF for the help getting this working. I would probably still be scratching my head to this day if it weren't for him. Hopefully this small guide has helped dispell the myths about these ports and shows just how easy it is to wire up something for them. Happy gaming!



18 comments:

  1. hi there. I need the exact same cable. Can you make one for me to purchase? Please email me at iwc5002@gmail.com Thanks

    ReplyDelete
    Replies
    1. Hi! Sorry, the best I can do right now is just provide this information. Hopefully someone out there will be willing to make it for you.

      Delete
  2. OMG! Thank you very, very, very, very, very, very much! I've had ALL my RGB stuff ready. The only thing left was to get around that damn strange and obscure 34-PIN port that no one knew about. You made one very very happy canadian!

    ReplyDelete
  3. Awesome, thanks for sharing! Now to try this with my old Sony set...

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  4. Not working for me. I get very dark picture with no white. Just red...

    ReplyDelete
    Replies
    1. If the picture is stable then your Sync is at least working, as well as the Red video line if its also coming through. Please double check your Blue and Green connections.

      Delete
  5. Hi, I want to make this, but I don't understand scheme. If possibile to see e photo of scart plug? You do a connection on that without touch IDC pin?
    Thanks

    ReplyDelete
    Replies
    1. Hi, if you search google for "scart pinout" you will find reference photos showing where each pin number is. You do not need to touch the IDC pins if you cut the cable and solder those to the scart head.

      Delete
  6. Thabks, pin 34 andò 1 join togheter without soldering on scart right?

    ReplyDelete
    Replies
    1. Yea that's fine, you can just twist them together, or solder together for a better connection.

      Delete
  7. Can I just make a cable that would take RGB and S-video or do I have to make a separate cable for each input?

    ReplyDelete
    Replies
    1. I don't believe S-video is supported since there are no lines labeled Luma or Chroma.

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  8. I did cable, but I can't switch to multiport input with compatible remote.
    Tv automatically switch on input or not?

    I have only IDC asus wire and is torque pin 10 to 16, but is the same and my soldering skill is not bad.
    Can you help me with this?
    Thanks a lot

    ReplyDelete
  9. I forgot, at this moment I don't have a RGB signal but I'm traing with a classic RCA video with scart adpter, I think must work

    ReplyDelete
  10. I do again with another cable, but tv dosen't switch on multiport input I think...Again I'm training with RCA video and adpter scart tu scart female cable I made...
    I don't know before buy rgb cables for my console I want to be shure all works fine with multiport

    ReplyDelete
  11. Do u think is ok for kx-20ps1 model? In the manual there are differrent pin like red on 25 ble on 26 like the classic pinout

    ReplyDelete
  12. Finnaly I try with rgb input on my adapter, works but image roll over and I can't stop with H sync on TV.
    What's the problem?Maybe some shit soldering?What pin?

    ReplyDelete