Sega Game Gear Troubleshooting
The Sega Game Gear, a portable version of the Master System, was Sega's first hand-held game console.
First, make sure the batteries are intact. Second, if your batteries have been used for around 5 hours, it has depleted all its energy. Simply replace the old batteries with new ones.
Use the AC adapter provided with the game gear to power the console, make sure you are using the correct model number (2103). Using the wrong AC adapter may result in damage to your unit.
Plug in a headphone compatible with 3.5mm audio jack onto the console. The sound will now come out of the headphone instead of the game gear.
Often if the speakers emit little to no sound but the headphones work fine, a capacitor needs replacing. See Note.
Adjust the brightness control dial located on the left side of the game gear to help reduce the problem.
Try moving away it from other electronic devices, such as: television, radio, cell phone, or any other type of electric interference.
Clean the button contacts on the logic board. If the carbon has worn down you can spray the buttons with a miniscule amount of carbon type paint that is commonly used to fix car window defrosters.
Electrical knowledge will be needed to fix the faulty capacitor, here is a video that will guide you to fixing and replacing the capacitor.