i fly quad copters and on a recent build i accidentally powered my video transmitter with 12v but on the 5v output pads... I didnt notice any smoke or sparks etc... and the 12v input had nothing connected to it.. but now the video transmitter LED's dont light up and it does not transmit any video. But the "antenna" components under the sheild still get hot like normal.

I do not see any physical damage at all on the circuit board. i can see only one smd fuse and it checks out ok... WHY WOULDNT THEY JUST PUT A DIODE ON YTHE 5V OUTPUT?.?.? i guess a penny or 2 is to expensive

Is there a common component that would normally fail under these circumstances? I have tried to find a schematic or any other threads on this issue and have found now

*** I did this to 2 of them that were brand new before I realized i was putting power into the output I KNOW BETTER TOO....

It is a:
AKK FX2 - VTX with 7-24v input with a 5v output to power camera.
I have included a picture

 

Without a schematic it's just a WAG as to what might have failed.

 

My guess is that you probably killed the main module.

 

Can you get the paper work? Have you got any equipment? It might be just a diode. Might be a chip too.

 

Can you identify the 5V out connections and the tracks on the board that lead to this?

(As to implementing a diode, you always get a voltage drop across them so you cant just use a standard fixed 5V regulator for the job. You also dissipate power which is a problem at higher loads.)

 

WHY WOULDNT THEY JUST PUT A DIODE ON THE 5V OUTPUT?.?.? i guess a penny or 2 is to expensive

Thats not done because if its a fixed V regulator now your output is ~ 4.3V if Si diode, and the diode is, depending on
how it was done, outside control loop adding to T effect and other errors.


Regards, Dana.