Modding A Pal Megadrive 2 - queries and checks

Hi all,

I'm thinking about modding my childhood PAL megadrive 2 so it can switch between 50hz and 60hz. I have an everdrive X7 on the way and already own a framemeister (using RGB) so would like it to be capable of running more games from other regions. It has some sentimental value and this will be my first mod so I would like to check a few things before starting.

The best guide I found was from these forums was on this thread. Its quite clear and uses the same board version but I'd like to double check a few things before starting! 2 posts from this thread concern me though.

- post #2 where Bearking talks about adding "pull up resistors on the switch". (I have no idea what this means and the images have expired so I can't see.)
- post#10 where a user is saying they've followed the guide but lost all video signal. (again I can't see the image they posted)
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Will I need to follow Bearkings advice on the transistors or is this simply optional? I'm hoping the #10 post from this thread is not related to that issue.
My board version is VA 1.8


The only difference I've noticed from the walk through is that there is a mysterious brown wire going from the solder point near JP3 to the Toshiba chip which I've never seen before. Would this require me to so anything different?



Other than that the rest seems straight forward. I've added some plans on pics of my MD2 board below.

I cut here for the pad leading to 107, scrape the point just above and add a wire.


I cut the connector coming from 52 and add a wire to the solder point below C8.



And add a wire to JP3 on my board.



Finally I will then solder each wire directly to a 3 way rocker switch. [No pic here as I have to get one, but it seems straightforward.]

From my understanding this will allow me to switch between PAL - 50hz, American NTSC - 60hz and JP NTSC 60hz and each point of the three way switch.

Does this sound correct? Am I misunderstanding any steps or options here?

I know that it will need further modification for other video signals to run in 60hz but I believe that should not be of concern at the moment as I'm using RGB

Thanks in advance for any advice on this!

 

I would go with the switchless mod. Bad_ad84 has preflashed chips available here https://assemblergames.com/threads/for-sale-modding-parts-chips-etc.39971/ along with install instructions.

 

Hey thanks for getting back. I haven't heard of a switchless mod? How exactly do these work? I checked the post but his guide seems to have expired. Would this be more complicated to install?

 

http://wolfsoft.de/wordpress/?p=322 Here's another site. Sorry didn't realise they were dead links. It basically wires a chip to the reset button which then activates the required mode depending on button press. A couple more wires required but cooler. It drives a 2-colour led as well to indicate mode.