Opening EA's unlicensed Genesis carts?

[Nemoide]

I've been on a kick replacing batteries in my cartridges in order to prolong their lives.

Usually, this is a pretty simple matter; I have the game bits required for standard Sega and Nintendo carts... but when I looked at my copy of Might & Magic for Genesis, I realized that I don't have a bit that will fit it. The screw design is apparently called a "tri groove" but I can't find more about it than that; it's a screw with three indents but with a spot in the middle sticking up preventing me from using the kind of screwdriver I'd normally use to open a Game Boy.

I don't really know too much about the technical specifications of different bits & screws, but does anyone have an idea as to what kind of tool can be used to open that thing?

[Gunstar Green]

Yeah, some EA games used holt-head screws.



Finding a bit today seems pretty difficult. Some thin needlenose pliers and patience might be the best way.

If you get a security bit set with these things in them, I've heard people have had luck but it's finnicky:

[Ziggy]

This may not be for everyone, but you can make a security bit like this kind fairly easily. I like to save old worn out screwdrivers for this purpose. You will need a bench grinder, and a cutting wheel on a dremel type tool as well. Just grind and cut it into the shape that you need. Do test fits to sneak up on the right size. I suppose if you don't have any old/worn screwdrivers, you could just buy a cheap one for this purpose. The bits circled in the pic below are the kind you need to open the Nintendo brand SNES power adapter. I was able to make one out of a busted flat head screwdriver and it worked perfectly.

[Nemoide]

So I ended up getting a #8 spanner bit, the type Gunstar Green recommended. It was a little awkward but it did the job! Then I had to wrestle with the plastic tab that keeps the cart closed... I ended up leaving it in and just pried open the other side to get the board in/out.

I also got a #4 tri-groove bit while hunting, which seems to be the perfect size for the screw, but won't fit into the cartridge's recessed well. (I'm holding onto it anyway JUST IN CASE.)

(I'm sure Ziggy's solution is a good one, but I lack the means.)