Right, it gets the power supply from the master unit, there is no power on-off switch. The chess unit and memory unit: you're not supposed to plug/unplug them while the chesscomputer is on. I bet the same will happen when you do this on the real device***. So, best thing to do is restart the emulation after turning one of them on/off.

***I really would not recommend trying it! You might break the chesscomputer.