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Mega Drive 2 home made RGB cable ...

Discussion in 'Genesis/Mega Drive' started by Michael Knight, Sep 26, 2001.

  1. Michael Knight

    Michael Knight New Member

    Hi!

    I need someone who can help me checking all the steps I have made to create a home made RGB cable for my MD 2 ... here I go ...

    First, I tooks some info I found around about Scart connectors :

    http://www.gamesx.com/hwb/ca_VideoTvScart.html

    With this information, I searched something about the port pinout of the MD 2 and I found this :

    http://www.gamesx.com/avpinouts/genesisav.htm

    Ok, with all this info, I started to wire from the AV port of the MD 2 to a Scart connector, and I only left without wiring those 2 pins in the MD 2 --> Audio Mono & Sync ... and what I have finally got?? Well, a black & white image .... maybe I have to re-wire the whole thing (I will do it tomorrow) and if you ask it, yes, my TV support NTSC signals as well as 60 hz

    D´oh! I forget to mention that I have modded my MD 2 to run at 60 hz ... so the real question is ... I am wiring it in the right way or I have wired something wrong??
     
  2. IceDigger

    IceDigger Founder Staff Member

    you can skip audio mono, but use sync instead of composite video for better quality.

    make sure you wire up +5V to pins 8 and 16 on the scart connector, or it will not switch to RGB.. it didn't, so it used composite video and thus b/w for you.
     
  3. Mike G

    Mike G New Member

    You can't use the MD2's (negative) Sync output via scart - that's only for a monitor with separate H and V Sync inputs.

    A scart TV will have a sync separator built in, so there are no problems with using composite video for sync in this configuration.

    The only other thing you need (apart from the switching input on pin 16, as Arakon rightly mentioned) is 75 ohm resistors in series on each of the Red, Green and Blue pins, otherwise the picture will be too bright and/or distorted. Everything else you've done is correct.

    Mike
     
  4. Michael Knight

    Michael Knight New Member

    Hi again!

    Well, I have tried to use sync instead of composite, and where I got was a good picture, but with distorted colors ... I know now that I have to put 75 ohm resistors ... well, the RGB cable works very well with composite, but I will try to buy those resistors and try how it works..... maybe tomorrow ......

    Ok, thank you very much, Arakon & Mike G!
     
  5. Eleven of 9

    Eleven of 9 New Member

    I have recently made my own RGB cable for the MD2, I used the sync output with a 2k resistor in series, and a 200uF capacitor on each of the RGB lines and it works perfectly. My television does make most video singals darker, than most TVs, so you may still need the 75R resistors.

    I hope this helps :)
     
  6. ExCyber

    ExCyber Staff Member

    is there a description somewhere of what a "standard" RGB signal looks like in terms of voltage/current ranges and waveform (particularly for things like sync periods)? I don't think I've seen references to an "official" standard, but since most RGB stuff seems to be at least marginally compatible, I think there must at least be a de facto standard of some kind...
     
  7. IceDigger

    IceDigger Founder Staff Member

    I think the RGB signal is normally at 0.7 V, and the genny spits out 1 or 1.5V.
     
  8. lettuce

    lettuce New Member

    Ive got a problem simular sort of with my N64, its had the RGB mod done on it, but now the contrast level is really low, i read the posts above, and thought that if i removed the restisters, that it would strengthen the picture and make it brighter, but it didnt, it just stayed the same!!! Is there any other way to get the contrast level at the right setting, by modding the scart cable?? obviously i can just turn the contrast up on the TV, but i would like to have it at the same contrast level as everything else without having to change it all the time. Any help is much appreciated
     

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