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Tried to revert 60Hz mod on PAL Mega Drive 2 - Broke it - What have I done?

Mystereality

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I've somehow managed to partially break my Mega Drive 2 (PAL VA1) when trying to revert a 60Hz/NTSC mod. I'm sure I did something stupid, but with my basic electronics knowledge, I'm not sure what. I'll explain what I did.

I converted the MD2 to 60Hz/NTSC a couple of years ago by simply cutting the trace near leg 46, as shown below. The console had been working fine at 60Hz since. My understanding is that this pad that I cut the trace to is connected to ground and when leg 46 is connected to ground, the console will be in 50Hz mode. When I cut this trace, leg 46 is no longer connected to ground and the console will be in 60Hz mode.

nSMnVEv.jpg

I wanted to revert the console back to 50Hz/PAL temporarily to test out a few games. So all I had to do was re-connect leg 46 to ground, right? I traced leg 46 back to JP3, which I have seen being used on guides for PAL/NTSC MD2 mods before. So if JP3 has continuity with leg 46, all I have to do is connect JP3 to ground, right? So I soldered a wire from JP3 to one of the many ground pads around the perimeter of the PCB (see image below) - This was maybe the mistake I made?

MD2_JP3.jpg

With my very basic electronics knowledge, my understanding was that I had now re-connected leg 46 (via JP3) to ground and the MD2 should be back in 50Hz mode. Well it was back in 50Hz mode, but not without some serious issues...

First of all, I could no longer get an output image from my OSSC on any Line multiplication mode. So I removed the wire I had just soldered in and I was still not getting any output on my OSSC. This seemed strange and I thought maybe there was an issue with my cheap RGB scart cable. It seemed too much of a coincidence for it to be an issue with the scart cable as it had been working fine for years, but I had to rule it out. So £30 later I now had a scart cable from retrogamingcables - Still no output from the OSSC...

I connected the console to a CRT and the Mega Drive still works, but the video output now has strange distortion issues at the top.

IMG_0271.JPG

I've also noticed the heatsink on the PCB now gets very hot. I'm not sure it got as hot as that previously? I'm also measuring 11.4V on the voltage regulator now, that's not right is it? Should be 10V?

So my question is, what have I done? What mistake did I make and is there anything I can do to fix it?

Thanks.
 
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cta

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Uh... Is there any reason why you put a jumper wire in a totally different place - instead of simply bridging the cut you made earlier?
 

Ergot

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Remove the wire and reconnect the trace you cut?
 
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