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Arcade Board Interlaced Display

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This topic contains 6 replies, has 3 voices, and was last updated by  marqs 4 months, 2 weeks ago.

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  • #11659

    GadgetFreak
    Participant

    I have an original Nintendo Popeye PCB that will not give a picture on my DVI 4:3 1600×1200 monitor.
    I know this board produces an interlaced image which is quoted as being 512v x 448h 30Hz. The OSSC does not always lock onto the signal and sometimes takes a few input switches before it displays steady reading of AV3: RGBS 514i 15.74kHz 61.25Hz. I am running the latest 0.76 firmware.
    The info button displays Vmod: 480i LO: 514 VSM: 1.
    Can anybody help with which adjustments I might make to get an image?

    • This topic was modified 4 months, 2 weeks ago by  GadgetFreak.
    • This topic was modified 4 months, 2 weeks ago by  GadgetFreak.
    #11662

    marqs
    Participant

    That’s a known issue which only affects AV3 input. Apparently the detection went worse with 0.76, so if you can’t connect the board to AV1 then I suggest trying v0.75 until the issue is fixed properly.

    #11666

    GadgetFreak
    Participant

    Tried it on AV1 and it’s basically the same AV1: RGBS 511i, 15.74kHz 60.61Hz Vmod 480i LO: 513 VSM: 0

    #11673

    ptepid
    Participant

    I had an issue with syncing a 625i signal on VGA with 0.76. It seems to be a bug with the new line 3-5 multiplier modes. The workaround I found was to set the 240/288p multiplier mode to Line2x.

    Your signal has a different resolution/refresh rate, so this may not be the same issue.

    #11674

    marqs
    Participant

    But it should reliably lock when using AV1 – right? If you don’t get any picture output, most probable reason is that your monitor cannot handle linedoubled 513-line signal. Standard 480p is 525 lines, and some monitors do not accept more than +-1 line variation.

    #11686

    GadgetFreak
    Participant

    ok, reverted to 0.75 but still no image.
    So I connected a bootleg popeye board and the picture comes up. The bootleg lcd info is AV1:RGBS 513i 15.60kHz 60.84Hz VMod:480i LO:513 VSM:0
    The original does show a good image on my old 1084 Amiga monitor.
    I am hoping I can make some changes to the 480i advanced timing menu but not sure what to change and in what order. Can anyone give me some pointers?
    I do have a scope and moderate electronics skills if I need to look more closely at the sync signal.

    #11696

    marqs
    Participant

    With 513 lines you should at least decrease V. backporch. Funny that bootleg board works fine with pretty much identical sync parameters. You might also want to try setting H-PLL pre and post coast to 3 in sync menu (is the red led on with either board?).

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