Trouble with Ghosting on SNES via SCART

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  • #36922
    JonIIDX
    Participant

    Hi everyone. I’ve been fiddling with my OSSC a lot lately to try to optimize the picture for both my RGB modded AV Famicom and my Super Famicom. Originally, I used FirebrandX’s presets for both FC and SFC, but I was getting a lot of extra jitters. Initially, I figured it was due to neither of my consoles having a de-jitter mod, but after I fine-tuned the H. Sample rate, the degree sample phase, and the H/V backporch, I got some great results on Line 5x for my AV Famicom. The jitter is significantly reduced from before.
    256×240 optim. Full Screen (FC)
    256×240 optim. 20x zoom (FC)

    After attempting this with my Super Famicom, I was able to get a pretty clean picture, completely free of jitter on 256×240 optim @ 1920×1200 4:3 mode, but I have two strange issues with the image that were not apparent in my AV Famicom.

    1) There is a thick bar of noise that goes from top to bottom of my screen. It is most visible on solid color backgrounds.
    2) I am getting a two pixel long shadow to the right of each prominent pixel.

    Here is a picture comparing an emulator (top) to the OSSC without noise (middle) and the OSSC with noise (bottom).
    Here is the full, unmagnified screenshot just in case it helps.

    The only reason I was able to get a clean capture without the noise bar is because it moves top to bottom, so I just made a screen cap when it already passed by.

    I am using the exact same power supply and the exact same Insurrection SCART cables for both consoles, but the Super Famicom is experiencing this issue when the AV Famicom looks almost as crisp as an emulator. Does anyone have any idea what could possibly be causing these issues? Thanks in advance for any ideas!

    #36928
    BuckoA51
    Keymaster

    What model of SFC are we talking about here?

    #36930
    JonIIDX
    Participant

    The model number is S22467202, SHVC-001.

    Upon further investigation, it appears that there is a chance that what I am experiencing is not ghosting (like found in the SNES Mini), but color bleed (which I didn’t even think was possible on RGB). I am also guessing that my added vertically scrolling, top-down noise bar is from the PCB within my Super Famicom. Apparently some consoles are just noisier than others. I am supposing the only way to alleviate this issue would be to buy a different model. 🙁

    If you know any specific information about the SHVC-001, it would be great if you could link me to it. I found a lot of resources documenting SNES consoles, but not much for Super Famicoms. Thanks.

    Edit: I used Mystic Quest (USA version 1.0) to determine that I have the following:
    CPU: Ver. 2
    PPU1: Ver. 1
    PPU2: Ver. 3

    • This reply was modified 5 months, 2 weeks ago by JonIIDX.
    #36953
    BuckoA51
    Keymaster

    Yeah unfortunately all the multi-chip SNES consoles have a slightly sub-par RGB image. You can try the reverse LPF option on OSSC to compensate for it.

    #36955
    JonIIDX
    Participant

    So, how do you know mine is a multi-chip? I found a lot of information about SNES models, but couldn’t find much about SFC models.

    Reverse LPF made a HUGE difference, by the way. Thanks for the suggestion! Sadly, I think I am noticing the noise bar even more… Currently I am using a third party AC adapter, and I have just purchased an official SFC AC adapter. It should be delivered in a couple days – I’ll give an update then.

    #36978
    Harrumph
    Participant

    SFC follows the same pattern of mobo revisions as US SNES, more or less. 1-chip model will also report chip revisions as 2,1,3, so only way to know your mobo revision is to open your console and check.
    Some are known to cause more problems than others, eg the APU variety.
    For the horizontal bar, sounds like a power issue. Trying a different AC adapter is a good idea. It’s possible you’d need to replace some caps or add more bypass capacitor to the power line. Cap kits can be bought from console5.
    More info

    SNES Vertical Line


    https://console5.com/techwiki/index.php?title=SNES

    #36980
    JonIIDX
    Participant

    Thanks for the information, Harrumph! I appreciate it. Well, I am not nearly brave enough to try soldering anything to my SFC, so if the OEM AC Adapter doesn’t fix the issue then I will just live with it. It’s funny, I never noticed the noise bars before when I was using S-Video through my GV-USB-2, they just became noticeable when I upgraded to RGB. I guess the step up in quality is pretty huge, so it is natural that imperfections would become easier to notice. Thanks again for the help.

    #37045
    JonIIDX
    Participant

    Update:

    The OEM Japanese Super Famicom AC adapter just came, and the noise problem has been completely rectified. The overall image looks much sharper too – I wonder if it has improved more than just the noise. Awesome!

    So glad I don’t have to change anything with my console’s PCB… Thanks for the support and information.

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