After several flights with my new hexa, I've run into a problem. Motor number 3 does not spin when the others do. Long story short, I narrowed it down to something with the PDB. If I plug motor 3 directly into the APM it works fine, but if it's attached via the PDB I get the 3 startup beeps (3S identified), but not the secondary beep that the other motors successfully have.
I completely detached the PDB and did some prodding with my multimeter. When I check the voltage from the ground to the signal pins with ONLY a 3S battery attached to the board, I get various results. Most of them are from 5 to 7 volts, while the signal pin for motor 3 is 12.4 volts (i.e. full battery voltage).
Now, I'm no electrician. Nor am I terribly knowledgeable concerning what these pins should read for voltages, but I'm confident something is amiss.
Is the problem with a 3DR hex PDB?