Game Gear Power board
This work is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License.
I have developed a replacement power board specifically designed for the new Game Gear mainboard. While its primary compatibility lies with the new Game Gear mainboard, it can also function with the original SEGA Game Gear under certain conditions.
It's important to note that this board is compatible with the original Game Gear, it does not include a 34V voltage regulator. Therefore, it will only function with an original SEGA Game Gear if the LCD screen has been replaced with a modern LCD TFT (IPS) kit.
The power board offers two power source options: a 3.7V LiPo battery or a USB-C connection. To prioritize power from the USB source, I have implemented a MOSFET load sharing circuit. When the USB is connected, it takes precedence, while simultaneously charging the LiPo battery using a Microchip MCP73833/4 battery management controller.
Given that the Game Gear requires a 5V power supply, I have chosen a TI TPS61032 step-up power regulator. This regulator efficiently converts the lower voltage to the required 5V. Additionally, it features a low-battery comparator thattriggers a VREF change, enabling the low-battery indicator on the Game Gear.
The DIP switches offer flexibility and customization, allowing you to tailor the power board's functionality based on your specific console version, battery charging capabilities, and LCD screen requirements.
The power board I have developed features three DIP switches that provide various options and functionalities:
- VA0 / VA1: This switch enables a more stable low battery indicator specifically designed for the original Sega dual-ASIC VA0 console. For the VA1 and all SYF mainboards, it is recommended to keep the switch set to VA1.
- 1.0A / 0.5A: This switch allows you to choose the maximum battery charging current. The appropriate setting depends on the capabilities of your USB-C power brick and the batteries you are using. If your power brick can deliver 1.5A and your batteries can handle 1.0A charging current, you can switch it to 1.0A. However, if you are unsure or using different specifications, it is recommended to keep the switch set to 0.5A.
- 34V / 5V: This switch is only available on the 34V version of the board. With this option, you can enable or disable the output of 34V to pin 9 of the connector. This feature is particularly relevant when using the board with the original SEGA Game Gear LCD, the requires 34V for the contrast circuit. Please note that this switch is not applicable to boards without a 34V voltage regulator
LiPo battery recommendation
I have been testing with the following sizes LiPo batteries:
- 124050 - 12x40x50mm 3.7V 3000mAh - Type L531
- 104050 - 10x40x50mm 3.7V 2500mAh - Type L374 (no longer available)
- 103450 - 10x34x50mm 3.7V 2200mAh - Type L339
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, BOM and PNP files here. Keep in mind the project has a Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0) license.