My Dreamcast internal HDMI mod

Discussion in 'Modding and Hacking - Consoles and Electronics' started by Somechump, Oct 10, 2018.

  1. Somechump

    Somechump Active Member

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    Here is my Dreamcast Internal HDMI mod.
    I decided to go with a RGB Scart to hdmi adapter, I know VGA is better resolution, and I initially had a VGA to HDMI adapter installed, but I didn't enjoy how it didn't want to display some of my games. So for better compatability I changed to scart.
    This is the one I used from Aliexpress.
    41e4PdB1FKL._SX466_.jpg
    This is the circuit I used, plus I added 220uF capacitors on the RGB lines.
    dricasryu.gif

    I wired to the bottom of the board and routed the wires along the back and up the side.
    My power wires are a bit long in this pic as I was still prototyping it.

    20181010_163636.jpg

    Hers is the back with the HDMI connector cutout, and a resolution select button above the AV port.


    20181010_163939.jpg

    Here it is connected and running Bangai-o. Good times.


    20181010_164213.jpg


    This was an fairly easy modification, only took an hour or so, and am pleased with the result.
     
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  2. Mord.Fustang

    Mord.Fustang Dauntless Member

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    Nice mod. I'm guessing there isn't any bad lag using that adapter?
     
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  3. Somechump

    Somechump Active Member

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    I haven't noticed any lag.
     
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  4. Somechump

    Somechump Active Member

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    Just added a video of some Hydro Thunder with this adapter
     
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  5. kyo86sg

    kyo86sg Intrepid Member

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    My question will be does it scale to 720 or 1080p?
     
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  6. Jord9622

    Jord9622 Site Supporter 2014 Site Benefactor

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    BEAUTIFUL WORK!
     
  7. citrus3000psi

    citrus3000psi Housekeeping, you want towel?

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    These Chinese scalers are all the same, have around 2.5-3 frames of lag. Cannot interpret 240p properly, and will display the DC in the incorrect aspect ratio.

    If you want an internal mod, just hold off a little bit longer, DCHDMI is in fabrication right now.
     
  8. MoockyLoock

    MoockyLoock Robust Member

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    Hehe
    Good news indeed !
     
  9. rama

    rama Gutsy Member

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    @Somechump: Is the HDMI chip near the HDMI output a "MacroSilicon MS9282" by chance?
     
  10. Somechump

    Somechump Active Member

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    It has multiple output resolution you can select, 1080P being the highest, but I found anything over 720P starts to make the image look darker and introduces a small amount of stutter.
     
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  11. Somechump

    Somechump Active Member

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    I was curious about this comment and your statement of it not displaying 240p properly, so I ran the 240p test suite and everything looked good, including the aspect ratio.
    How exactly does it not display properly?
     
  12. Bearking

    Bearking Konsolkongen

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    Does it pass the drop shadow test? If the shadow is displayed as horizontal lines, then it means that it deinterlaces 240p which is wrong. The shadow should be solid and only shown every other frame.
     
  13. Somechump

    Somechump Active Member

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    I see. Thank you for the info.
    Well I can't comment on the effectiveness of the scart to hdmi adapter, as my TV shows horizontal lines during the drop shadow test with both the AV output and the hdmi.
     
  14. Bearking

    Bearking Konsolkongen

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    Then the SCART to HDMI scaler doesn’t properly support 240p, meaning that it sees it as 480i and adds deinterlacing, which causes these stripes.
     
    Last edited: Nov 11, 2018 at 2:27 PM
  15. Somechump

    Somechump Active Member

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    There is no evidence that it is the adapter, as I said my tv has the same result when I use the av cable.

    Anyway. I am happy with the result.
     
  16. MonkeyBoyJoey

    MonkeyBoyJoey 70's Robot Anime GEPPY-X (PS1) Fanatic

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    But it is the adapter.

    The TV doesn't see 240p, it sees whatever the adapter is outputting (such as 1080p). The damage is already done. This happens over composite video direct to the TV because the scaler in your TV suffers from the same issue as the converter, just like many modern HDTVs and cheap converters.

    A properly scaled image with a proper upscaler is always better than these cheap things. I have one of those converters and quite honestly, it is junk. The aspect ratio is stretched to 16:9 when it should be 4:3 with black pillars on the sides. Setting the TV to 4:3 helps but it still doesn't feel right to me.

    This has been common knowledge for a few years thanks to rigorous testing by people in the community with the proper tools.

    I highly recommend waiting for the HDMI mod as it will not suffer from any of this.
     
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  17. Bearking

    Bearking Konsolkongen

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    Yes there is. Had the SCART adapter worked properly with 240p, the drop shadow would look correct on your tv, as the tv would be getting a 720p image through HDMI. A modern tv would never deinterlace a 720p signal.

    That you get the same issue on your tv using an av cable just tells us that the tv doesn't properly support 240p either.

    Edit: MonkeyBoyJoey was faster :)
     
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