Hey everyone, I'm starting in the FPV quadcopter world, and I got a NAzgul5 V2 a while ago. It worked fine, but I broke a motor and kept it away for a long time.

I finally got a new motor, succesfully installed it, updated everything, flashed bluejay, and I was configuring the drone in betaflight, step by step.

Everything was fine, but in the middle of setting it up, I plugged in the battery and when I went to plugin the USB cable and it touched the USB port, smoke came out of the Flight Controller. I instantly plugged the battery off. Nothing seemed wrong, so I kept setting it up. When I got to the Video transmission tab, I noticed the VTX wasn't working, and there was no LEDs coming from it. 

I tried turning the FC on with the battery plugged in and noticed that no LEDs came up from the FC nor the VTX, but the startup sound came up. However it wouldn't connect to the radio controller, or anythying, it wouldn't arm, nothing.
 
However when I plug in the battery with the USB connected, everything works, I can control and arm with the radio controller, only video transmitter doesn't work, it shows no LEDs, no sign of life.

I unpplugged everything and noticed the underside of the FC is burned.

It would be great if someone could point me in the right direction to fixing it. 

I read it is most likely a PDB issue, probably shorted it, but I don't know how to fix it or where to start.

Should i just get a new FC?

Is it possible the VTX is also damaged?

Thank you in advance.



 

Here's a video that better shows it. (the flight controller got hot after I finished recording and unplugged the battery)



this is the burnt part

Unfortunately you've fried the onboard 5V regulator. That is the exact root cause of the symptoms and behaviour you have described. You have one of the following 3 options:

1. Locate and replace the 5V regulator SMD component on the FC (requires good soldering skills).
   
2. Use an external 5V BEC to provide the FC with 5V.
   
3. Buy a new FC.
   

(16-Feb-2023, 09:09 AM)SnowLeopardFPV Wrote: Unfortunately you've fried the onboard 5V regulator. That is the exact root cause of the symptoms and behaviour you have described. You have one of the following 3 options:

1. Locate and replace the 5V regulator SMD component on the FC (requires good soldering skills).
   
2. Use an external 5V BEC to provide the FC with 5V.
   
3. Buy a new FC.
   

Thank you for your answer. I'm gonna look into it.
What about the burned capacitor?

(16-Feb-2023, 03:50 PM)Gabiru Wrote: What about the burned capacitor?

That is likely what you actually shorted out when you slipped while trying to plug in the USB cable because it looks like that capacitor is on the underside of the board right below the USB port so it would be quite easy to accidentally touch the end of the USB cable plug onto the connections of that capacitor, thus creating a temporary short which could then have blown  the onboard 5V regulator chip.

You might find that the capacitor itself is fine and is just externally charred a bit from the voltage short across its external solder joints, but it would probably be worth desoldering and using a multimeter to check if it has a capacitance reading or if it is measuring a short circuit across its two contacts. If it has a short then just try connecting a LiPo back up to the board with that capacitor still desoldered from the board. The other two capacitors next to it on the board likely run in parallel to that one so there will still be capacitors across the positive and negative rails albeit a bit less capacitance. If the board still doesn't power up with that capacitor removed, then it means you have also fried the 5V regulator chip.

If the board powers up with that blackened capacitor removed and it is measuring a short across its connections when off the board then you can either try leaving it off (meaning the overall capacitance across those connection will be a bit less, so less filtering), or you can desolder one of the other two from the board to measure the capacitance and then get some replacements of the same size / capacitance so you can use one in place of the charred capacitor.