SNES 5x jitter when TX mode = HDMI, but DVI ok

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  • January 6, 2019 at 5:49 PM #24626
    MegaSuperSuper
    Participant

      Hi,

      I’ve had my OSSC 1.6 for a few months now, and I’ve been really happy with it. It’s working very nicely for both my SNES and MegaDrive. I have one problem, which only affects the SNES in 5x mode on my TV (a Samsung LE40C750). I only get a stable image if ‘TX Mode’ is to DVI. If TX Mode is set to HDMI, the image jitters horizontally and audio cuts out. 5x mode with TX mode set to HDMI works perfectly on my MegaDrive.

      To resolve this problem, I’ve tried various HDMI cables (all of which work with my PS4 at 1080p/60Hz); None solved the problem. I also tried playing with the ‘HDMI ITC’ and the ‘Full TX Setup’ settings to no avail.

      Does anyone know why my TV might behave differently for the OSSC’s HDMI/DVI signals?

      The OSSC is flashed with firmware 0.82a. The SNES is a US 2-chip model. The MegaDrive is a UK model, with an oscillator mod to display NTSC content at 59.94Hz.

      Cheers!

      January 6, 2019 at 7:11 PM #24627
      nmalinoski
      Participant

        The SNES (and NES) is known for having a jittery sync, and there is a mod available for it to give it a regular sync cadence.

        As for the MegaDrive, I think (and someone can correct me if I’m wrong) it’s probably related to the mod. BuckoA51 even made a video regarding 60Hz mods not working properly, resulting in sync that is off-spec enough to cause problems on flat panel displays.

        January 6, 2019 at 7:19 PM #24628
        MegaSuperSuper
        Participant

          Thanks for the reply. I’m aware of the SNES/NES sync mod, but as I mentioned in my post my TV does work with my SNES. The only problem is when OSSC TX Mode is set to HDMI. DVI works.

          MegaDrive actually displays perfectly in all modes. It’s not just 50/60Hz switch modded, I installed a dual frequency oscillator too, so it outputs a correct 59.94Hz signal.

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