Game Gear LiPo Power Board
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
I have made a replacement power board for the new Game Gear mainboard. It has been specifically designed for it, however with the right conditions it will also work with the original SEGA Game Gear.
The board can be powered using a 3.7v LiPo battery or via USB-C. I am using a MOSFET load sharing circuit that prefers the USB over the LiPo. While the USB is connected, the LiPo battery is also charged using a Microchip MCP73833/4 battery management controller.
Since the GameGear is powered using 5v, I am using a TI TPS61032 step-up power regulator that converts the lower voltage to 5v. This regulator also has a low-battery comparator, which will trigger the change of VREF that will enable the low-battery indicator on the GameGear.
This board will work with an original GameGear, but it lacks a 34v voltage regulator, so it will only work if the LCD screen has been replaced with a modern LCD TFT (IPS) kit. Also, there is a slight difference between the battery indicator circuit for the twin-ASIC (VA0) and single-ASIC (VA1). In case of a twin-ASIC model, you should change R10 and R11 to 1.2K.
LiPo battery recommendation
I have been testing with the following sizes LiPo batteries:
The 124050 is the maximum size that fits into the battery component. I strongly recommend a larger 2500-3000mAh battery in case you use a less power efficient LCD screen (McWill, RetroKai, Funnyplaying).
In case you like to make your own board, you can download the gerber files here. Keep in mind the project has a Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) license.
To cover the hole of the DC jack, you can 3D print this STL. I recommend you to print it with a transparent type of plastic, so the charging status LEDs will be visible.