mega drive 1 multi region mod

Discussion in 'Repair, Restoration, Conservation and Preservation' started by somacast, Aug 3, 2018.

  1. somacast

    somacast Spirited Member

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    hi ,

    I installed multi region 3 way switch mod on my mega drive and it works perfect, just wondering what makes its colors display black and white with Japanese and US games (colors are fine on PAL games) when using my av to hdmi adapter to play it in 1080p on my led tv ?
     
  2. bart_simpson

    bart_simpson Dauntless Member

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    The sony cxa1645
     
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  3. Taijigamer2

    Taijigamer2 Gutsy Member

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    Are u feeding CVBS or RGB to the hdmi converter? Is your mega drive a PAL model?
     
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  4. Lum

    Lum Officer at Arms

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    This takes more than a toggle switch to work correctly.

    A PAL console at 60hz (or an NTSC console at 50hz), is running in an unintended state. Messing up things like the color encoding.
    RGB can help, but isn't a perfect fix. Some TVs are fussy about video sync rates.

    If I remember right, the fancier region mod is to have the switch also make NTSC and PAL use their respective crystal oscillator.
     
    Last edited: Aug 5, 2018
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  5. somacast

    somacast Spirited Member

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    and what is that exactly??

    No iam not, I just made the switch mod and using the regular av out cable from its regular output in the backside of the MD1, the region changes for sure, but the colors don't come with the other 2 regions, yes its PAL Mega drive 1.

    I need more details please, I will buy additional crystals if required, but need some clear tutorial for this part as most of tutorials that I have seen are only referring to the switch and demos it working..
     
  6. Lum

    Lum Officer at Arms

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    Okay it's easier to try a RGB cable. Likely what tutorials made in Europe are showing, and will have color on most SCART TVs.

    You should ask someone more experienced for the details. I'm not a modder myself.
     
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  7. somacast

    somacast Spirited Member

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    ok thnx , I am waiting for an expert opinion of course!
     
  8. Taijigamer2

    Taijigamer2 Gutsy Member

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    The AV port is capable of outputting both RGBS and CVBS (Composite video). U are probably using an AV cable which only transmits CVBS. With CVBS, the colour is encoded into the signal using a subcarrier frequency. This is a different frequency for PAL and NTSC (4.43Mhz and 3.58Mhz respectively).

    The problem is the CXA1145 (MD1/2 video encoder) is set to the frequency of its region (either PAL or NTSC) and is therefore unable to encode the colour burst on the CVBS signal properly for import games, therefore resulting in a black and white picture. RGBS doesn't suffer this because the Component colour signal is not encoded with the subcarrier frequency.

    Also as @Lum stated, the frame rate difference also messes up some HD TVs and hdmi scalers like Frameister.

    Solutions in ascending order of difficulty - RGB cable > buy a NTSC megadrive > install a dual frequency oscillator https://nfggames.com/forum2/index.php?topic=5744.0

    I would start with an RGB cable anyway to get colour back in your imports then see how your TV handles the 60hz games.

    https://en.m.wikipedia.org/wiki/PAL
     
    Last edited: Aug 6, 2018
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  9. somacast

    somacast Spirited Member

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    thnx alot , i will do as you said and i will let you know what happens
     
  10. somacast

    somacast Spirited Member

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    further to this reply , i was thinking if there is a way to customize a cable to give me component output instead of scart , because our region tvs never used those scarts, and i will end up having to buy also scart to hdmi .. while i can connect component 5 wires to many tvs .. just wondering
     
  11. malcolm

    malcolm Rising Member

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    Agree with people saying use RGB, its much better. Going from composite to rgb, is like cleaning a layer of dirt from your monitor.

    I have done the colour correction on md 1's and 2's quite a few times. It takes a decent amount of fine tuning to get the picture right. Here is a guide that seems to cover the mod
    https://www.retro-otaku.com/2010/07...z-in-full-colour-in-rf-composite-and-s-video/

    If you want to use component, you will need an rgb to component or a retrovision cable.

    Or even a scart rgb to hdmi converter

    What country do you live in?

    Im thinking of off loading some loewe rgb tvs
     
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  12. L2000

    L2000 (",)

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    There is a way to build a RGB to component converter that works in line with your cable , check over at Sega16 for Helders RGB circuit , I think that’s what it’s called , there’s even people making boards of this circuit. You could always do the 50/60hz colour correction mod internally but beware it does entail lifting pins and separating traces as well as soldering , I don’t know what level or proficiency you have with electronics.
     
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  13. somacast

    somacast Spirited Member

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    considering all the retro consoles i have i guess buying a scart to hdmi is not a bad idea along with av to scart adapter to cover it all , I live in Bahrain :)
    thnx alot , i will see all of it then decide , i would rate my skills as very good , I've been into electronics since childhood, and i did many consoles mods at home including original xbox, xbox360, and the useless dreamcast sata - ide hdd mod.
     

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