OSSC and PAL 60hz Megadrive

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  • January 9, 2026 at 2:57 PM #68207
    ianrendall
    Participant

      Just got an OSSC that has been modded to a 1.8. My Megadrive mk1 has a 3 way toggle that switches Jap/US/EU (60/60/50hz). It’s the trace cut mod. This mod works fine over the RF connection, and worked fine on my previous 1.6 OSSC which I no longer have

      I am using the same TV so that is also fine.

      When the console is in the PAL 50 mode it’s perfect no issue. The problem is the 60hz modes.
      <p style=”text-align: left;”>
      It will display an image. Sound is full speed but bad quality, and the image looks like it’s just pass through. I navigate to the output settings and I can change them 2x, 3x, 4x etc but there is no change. Fiddling with coast, vth and pretty much everything else also has no effect. The LCD is showing 59ish hz but also 1543p, which is obviously way off. I had to roll back from 1.12 to 1.01 as it was the most stable. I am using a generic Scart cable, which worked fine before but I have just ordered a decent one from RetroSix. I also have a CRT I can test on but not until next week. I’ve a feeling it’s the console or cable at fault here, but I’m open to any thought you may have. Thank you.</p>

      January 10, 2026 at 11:07 AM #68211
      BuckoA51
      Keymaster

        I’ve used OSSC with several different Megadrive consoles, modded to 60hz without new oscillators and never run into this problem. Is your cable using csync or composite video for sync?

        January 10, 2026 at 12:32 PM #68212
        ianrendall
        Participant

          Thanks for your reply. It’s a basic cheap Scart lead so I don’t know the specs. It was bought on eBay from Hellfire Trading. I have a decent cable on the way and will be able to test with a crt soon. I did notice when I took the console apart that part of the mod switch was touching the ground plane so I may investigate that further.

          The cable plug doesn’t fit particularly well in the console. Moving it around produces a reaction on the screen but only in 60hz mode. Cable/socket/capacitors are my biggest suspects at the moment.

          January 10, 2026 at 1:08 PM #68214
          marqs
          Participant

            59Hz with 1543p indicates there are lots of fake horizontal sync pulses present that get treated as start of new scanlines.

            January 10, 2026 at 1:24 PM #68216
            ianrendall
            Participant

              Hmm. That sounds like a console issue to me.

              January 13, 2026 at 5:59 PM #68254
              ianrendall
              Participant

                Update.
                new cable arrived. Fits much better than the generic cheap one.
                Problem with the OSSC persists as before. Connecting to my 10” crt yeilds unsatisfactory results also. It will give sound but no picture in both 50/60hz modes with the new lead. The old lead will supply picture and sound at 50 and rolling picture and sound at 60. I believe the problem may lie in the Megadrive DIN socket, which may have been put out of shape by the bad fit of the cheap cable, or the clock crystal needs replacing. Interested to hear thoughts!

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