The Power board has 3 parts U1 is for when the USB cable is attached, it takes the 5v and knocks it down to ~3v for the other two circuits. U2 is for a 3.5v source that powers the LED, IR LEDs and the Rumble motors. It's TP7 on the MCU board. U3 is for the 3.3v source that powers pretty much everything on the MCU board. It's TP9 on the MCU board.