OSSC Pro – RGB Scart Output not working

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  • January 28, 2026 at 5:15 PM #68478
    Chris-130
    Participant

      Hi,

      I just received my OSSC Pro together with the Extra AV Out expansion card and the AV Input/Output Adapter v1.3.
      My main goal is to downscale to 240p / 480i RGB SCART for use with a consumer CRT.
      Unfortunately there seems to be an issue.
      Everything is connected correctly, but I only get a black screen over RGB SCART.
      The component output works fine, but RGB SCART doesn’t.
      The VGA cable I’m using is fully wired.
      (I tried two Vga cables and two scart cables)
      I tested this setup on both my Grundig consumer CRT TV (RGB SCART) and my Sony LCD TV which also has scart inputs.
      On both TVs I get no picture, only audio.
      On the Grundig CRT, I see a very brief glimpse of the test pattern when switching from TV channels back to the AV input, but the image disappears immediately.
      I have tried the OSSC Pro test patterns (480i/576i),different resolutions and also connected my Wii via component as input.
      I have tried all the switch positions on the AV Input/Output Adapter.
      I installed the latest firmware and selected RGBS and scaler mode “CRT “.
      Nothing changes the result.
      At the moment it looks like the AV Input/Output Adapter v1.3 might not be providing the required RGB voltage, but I don’t have the equipment or technical knowledge to perform voltage measurements.
      Has anyone experienced similar behavior or has an idea what else I could check?
      (Posting here as suggested by Matt from VideoGamePerfection).
      Thanks in advance

      January 28, 2026 at 11:32 PM #68480
      marqs
      Participant

        Could you take and post picture of the adapter? It sounds like the diode on the status voltage line may have perhaps been installed the wrong way.

        January 29, 2026 at 3:57 PM #68484
        Chris-130
        Participant

          January 29, 2026 at 8:31 PM #68486
          marqs
          Participant

            The diode seems to be installed correct way. I can thus see only 3 potential explanations:

            1. The diode is broken. Unlikely but not impossible. Requires multimeter to verify.
            2. VGA cable does not carry DDC5V. This is typically only true for cables which lack the corresponding pin that is easy to verify.
            3. SCART cable does not carry RGB or status voltage. Typical for thin cables meant for VCR composite hookup. Can be verified by opening connector on one end and checking if wires are connected to pins 7, 11, 15, 16.

            January 29, 2026 at 8:35 PM #68487
            Zacabeb
            Participant

              The D1 diode looks to be the right way around in the picture.

              I noticed though that pin 8 (CVBS signal status) in the SCART socket is unconnected in the adapter, which might cause issues with some TVs as they only switch to the input if it has voltage (+5V to +12V) and otherwise ignore it, even if pin 16 (RGB signal status/fast blanking) is active. I don’t know if the Grundig and Sony TVs in question are affected by that quirk though.

              Edit: Marqs’ suggested causes in the post above are probably the more likely ones.

              January 30, 2026 at 12:33 AM #68488
              BuckoA51
              Keymaster

                You can still manually select the input even if that’s the case, I’m not aware of any set actually needing pin 8 to get a picture (though there’s a first time for everything I suppose).

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