On the aft-side, this circuit appears to be the BEC. It creates 5-volts (actually about 5.2v) for the RX and APM FlightController. It only requires 2 wires ... Red/+5/Positive and Black/Ground/Negative. At the build-factory, they sometimes use standard 3 wire servo-cables, so the white-wire should not be connected. You might find the 3rd white wire first soldered, but then cut at factory later (this is normal). You can go ahead and remove the short piece of remaining white wire.
Being a core component, trying to determine the Power Board's specs and abilities. The IC chip is a MP1593DN, which I believe handles up to 3amps.
Most of the plating (giant traces if you will) on the top of the PowerBoard are Ground. Most of the large plating on the bottom (or under-side) of PowerBoard is +12v (again, direct to LiPo battery). But don't take my word for it ... examine for yourself and use a volt-meter to measure if in doubt.
More about Power Distribution Board (PDB).
|Quanum Nova with stock PowerBoard (v1.5) - VCC 5v output from BEC while flying (under load). APM_252, FrSky-X8R, 3DR-915 Telemetry, stock GPS and Compass. |