Sega Mega Drive 1 Colour Issue?

jamie666

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I am in the UK and have a pal Sega Mega Drive 1 that has been modded with a 50/60Hz switch. When I switch over from 50hz to 60hz, select back and forth on my switcher or go through the AV channels on the TV remote the picture after a few seconds suddenly gets brighter and more vibrant like someone has turned up the colour setting a few notches.

It will either do it when flicking the switch on the console from 50hz to 60hz or when and I select another channel on my switcher box or press the source button on the remote and get back to the Mega Drive. Basically whenever the TV decects the picture it starts off kinda dull then all of a sudden increases in colour.

I have tried the recreate this with my Super Famicom that has a switchless mod but no issue at all with the Super Famicom. I'm guessing it's comething to do with the TV adjusting to the Mega Drives video output signal? I would send a video but with the refresh rate of the TV its close to impossible to see it through a camera. Basically after I switch Hz or input after a few seconds or so the colours get brighter and more vibrant.

Can anyone offer any info on whats going on? Using a CSync RGB cable from retro gaming cables.
 

jamie666

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I have indeed. I have tried it on my HDTV and it does not have this issue leading me to believe its probably the TV. Seems like a very odd issue that none of my other consoles do, only the Sega Mega Drive.
 

ratson

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Mistake corrected in next post.
 
Last edited:

segasonicfan

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50 and 60 hertz used different timing oscillators to create the color burst in the chroma encoder. It's possible that when your TV is detecting the different refresh rates it matches its own internal clocks with the color burst signal differently, and decodes it differently. It definitely sounds like a problem on your TV's side of decoding the color signal. What you describe isn't really possible on an analog television
 

ratson

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Ah, stupid me, it wasn't the 50/60Hz that had different brightness. It was with scart vs composite ☺️
 
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