I show how to install a replacement battery in a Yamaha DX7 synth. DX7 batteries installed (parts & labor) for $20 + return shipping! Contact me for details. Yamaha DX Series Replacement Battery
I give a quick demo of the functionality of the Yamaha SK-10 analog synthesizer, and perform a light service on it–cleaning switches and sliders and recapping the power supply. This keyboard is currently for sale on my site.