Question regarding SNES PAL consoles

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  • August 14, 2017 at 12:39 PM #14398
    Harrumph
    Participant

      It works because it has a sync stripper in the scart head. It takes the composite video signal and filters out the video content. This type of cable exist because some switchers and video monitors only accept csync.
      It will work fine on the OSSC also.

      August 14, 2017 at 2:30 PM #14399
      paulb_nl
      Participant

        You should verify with the seller that your PAL csync cable with sync stripper has a 470 Ohm resistor on the output of the sync stripper. The resistor is missing from the photos on their website. The OSSC is not designed for TTL level sync on the SCART input so the resistor needs to be on there.

        August 14, 2017 at 7:16 PM #14408
        Harrumph
        Participant

          Oh, I was assuming since it uses composite video as the source, it would be at the correct level already. Guess not then?

          Edit: I see in the scart schematic for PAL snes, it does need a 75 Ohm pull down resistor on the composite video line. So the addition of 470 Ohm resistor implies that there is some amplification due to the LM1881 circuit? Sorry if it’s a stupid question, I’m not that knowledgable in electronics…

          August 14, 2017 at 9:23 PM #14410
          paulb_nl
          Participant

            Apparently the LM1881 always outputs 5volt TTL sync. Viletim talks about it here: http://shmups.system11.org/viewtopic.php?p=1153713#p1153713

            August 14, 2017 at 10:38 PM #14411
            marqs
            Participant

              Yes, there are 3 flaws I’ve repeatedly seen in most “sync stripper” cables:
              1. Missing 75ohm termination resistor in LM1881 input (before the cap)
              2. LM1881 is placed inside the scart assembly at the display end of the cable, even though ideally it should be on the other end
              3. Missing 75ohm sync driver (or series resistor) on LM1881 output (OK if the purpose is to generate TTL level sync)

              In practice, the end result is often still somewhat working even if all those flaws exist. The effective voltage level from LM1881 drops to much lower level if directly loaded by 75ohm termination inside TV, OSSC etc.

              August 24, 2017 at 8:54 AM #14726
              jonlad
              Participant

                @BonzoBits – how is your TV (UA55D6000SMXXY) running with the latest firmware revisions? Does SNES work on it?

                Thanks!

                September 5, 2017 at 8:32 AM #14939
                b0nz0beavis
                Participant

                  @jonlad I just answered in the TV Compatibility Thread. Not sure yet, will update once I’ve been able to do a test. Won’t be for a while though.

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