I recently bought this :
In order to be able to read voltage levels AND power the APM unfortunately without success, my APM board is fully functional when connected via the USB port and I have even carried out the calibration without a hitch, just no power from my 3s Lipo ..
I revisited the problem and noticed that my PWR module is missing what I believe is the the 5V switching regulator .. ( yellow part )
If anyone could tell me what component this is, maybe I could order it and get the board to work, if not then even an alternatvie part which can also do the job ..
attached is a photo of what I think the PWR module should look like ..
Finally, why would ebay or other shops supply these modules without the regulator ??