BetaFPV 2-4S 12A board - weird ground

[romangpro]

There are 3 sets of power pads:
top = for receiver
right = for LED
bottom left = for vtx

Nothing I connected to the bottom 5V would work. No lights. Nothing.
The vtx +5V is 5V to battery gnd, but ..20mv.. to the adjacent gnd pad.

Then I thought I have a dead camera because video out is blank.
Do you think its dead AT7456E OSD chip or something else?

[voodoo614]

The ground next to the LED is not a common ground but likely connected to a PINIO. And it only connects to ground when activated. Most FC usually make some kind of marking to indicate that it is not a common ground. They do the same for Buzz, where there is usually a Buzz+ and Buzz-. So you can't connect your VTX to that ground pad and expect power.

[romangpro]

The betafpv site shows vtx wired to pads pointed by red arrow.

[SnowLeopardFPV]

This is BetaFPV product we are talking about here so why am I not surprised. The 5V pad denoted by the red arrow should work the same as the other 5V pads, so I guess there is either a fault on the board or general design flaw with that version of the FC and is probably a reason why there have now been 4 versions of that same FC.