Iv got no power to my vista on closer inspection Iv discovered this, on watching loads of youtube vids I cant find a definitive answer whether this is at fault…
I’m 50/50 as it looks a different shade of black to to the others?, before I go removing it Id like to be 100% that is the issue.
Iv tried testing with a meter but to be honest I’m not sure what I’m testing for, or where I should have continuity? any help would be greatly appreciated…
Have a look at this
Looks like the RX diode has blown
Power is applied to the Vista on the other side of the board. Logically one of the first components connected to the supply rail would be some sort of regulator, to provide the 5V/3.3V supply to the rest of the board. I would try to identify the regulator, check to see that the supply voltage is present on its input. If it is then check if you have a 5V and 3.3Volt output.
As the circuit board is a multilayer construction the regulator need not be on the same side as the supply input.
Ok iv tested what I could as I only have a normal test meter and discovered I do indeed have power on the back of the board. Iv circled the 2 components that have power but not sure what they are…
So does this mean the dreaded RX diode has gone?, if so I can see by all the tutorials on YT this can be repaired hence not to worried. Not sure if the no power LED is an indicator of this also.
Both components appear to be diodes. The one labelled B8 is a zener Diode, used for basic voltage regulation, the L7 Diode I think is used for current limiting.
Hmm i think it going to take some more digging before i start removing the RX diode
Diodes are very cheap. Worth a punt
Out of curiosity whats the actual issue Nick? Whats it doing or not doing?
Im pretty sure those diodes are for rx, tx and sbus. Not sure that would stop the vista from powering up? I have seen you can buy just the power board for the vista but I can only find it in the US for $65 but then its another $25 for the cheapest shipping
The problem is I have power going to the board, I have power to some of the diodes on the board as circled above, but the red led doesn’t power up. I did a bit more digging last night and found someone had a similar issue and they found it was the antenna.
They stated, because the antenna wasn’t attached the board wouldn’t power up, I find this hard to believe but at this point I’m willing to try anything as to get back in the air. The strange thing is I have 2 boards both with the same problem, and the frustrating thing is I’m running out of options and ideas as to test and what’s wrong with them…
DJI FPV Air Unit Burn Out - Did It Work ? - YouTube. This may give you some nuggets of info?
Well checked the antenna thing and its a no go, really cant get my head round why I have power on the board but none to the LED.
Thing is, is it the TX diode stopping it from powering up?, do I risk removing it.
@Kellybob good find thanks Iv had some correspondence with Ian many moons ago regarding something else.
So I might drop him a line asking for a few pointers, I know the above is an Air unit but Im sure he might have some idea, well more than me as where to go next…
If not I could be looking at a bill of £180 
Why £180 Nick?
A group you may be interested in.
As I would have to replace 2 
Iv now emailed cyclone FPV for some advise due to being at the end of my fault finding capability, so I can only see if he gets back to me with some advice.
Big thanks to everyone who has partaken in this endeavor…
Just found this Nick on HobbyRC
Now I dont know for sure its compatible as it says its Runcam Link but in description it says replacement for Caddx Vista, Runcam Link, DJI Air Unit Lite. Might be worth a quick email to HobbyRC to check
Cheers mate Ill drop them a line 
Just watched this hence It might not be my top board that has the problem but the bottom which I’m nipping to check on now, fingers crossed
