9 Nov 2016

Sega Game Gear country switch

Despite the fact the Game Gear isn't region zoned, it does exist a difference between a Japanese model and an overseas model (USA/EUR).
Just like the Master System and the Megadrive, a specific pin on one of the ASICs specifies the region.
This has the following impact: some Game Gear games display  different title screen or Japanese texts when played on a Japanese Game Gear. Same goes with Master System games played with a Master Gear converter.


Material needed:
- a cruciform screwdriver
- a gamebit screwdriver (for the cartridge port screw)
- a soldering iron and some solder
- thin wire (kynar for instance)
- a small needle
- an ON/ON switch (SPDT type)


Step 1:


Open the console : there are 6 cruciform screws and 1 gamebit screw



The two halves can be separated by removing the 3 cables linking them together:


Step 2:

Identify the concerned chip:

For a model 1:


For a model 2:


Step 3:

Identify the concerned pin:

For a model 1 (7th pin in the left row starting from the bottom):


For a model 2 (3rd pin in the top row starting from the left):



Step 4:

This is the tricky part. Heat up the pin with your soldering iron and lift it with a small needle.
Be careful not to bridge pins together, lift other pins or break any pin.

Step 5:

Install the switch.

Connect the center pin of the switch to the lifted pin.

Then connect one of the remaining pins to +5V (+ side of the capacitor, see pics below):

For a model 1:


For a model 2:


Finally connect the last pin of the switch to ground/0V (- side of the capacitor, see pics below):

For a model 1:


For a model 2:


Results:

Some Game Gear games should now display a Japanese title and/or Japanese texts when the console is set the Japanese region:


And some Master System games played with the Master Gear Converter should display a Mark III splash screen on startup:


Sources:


Sega Game Gear Maintenance Manual - August 1992 (model 1)
Sega Game Gear Service Manual - VA1 (model 2)

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