Hi guys,

I really need help to debug this issue

I have a new XRotor F7 FC + 60A ESC stack.

RX is CRSF


iNav or BF can connect to the FC when connecting the USB, but the CRSF RX is not powered.
now, if I connect the battery while the USB is connected the usb connection with either inav or BF is lost but all peripherals are now powered.

I would like to know the reason why before I attempt to replace the FC.

whats going on?

The F7 in this case will not power up receivers unless it’s powered by a LiPo.
  Some FC power up receivers from the usb others won’t.
I use the F7 convertible and what your saying about RX getting power after powered with LiPo is the way it works.

Just plug in a usb and test the 5v pads to check which ones power up. There must be one 5v pad that powers up via usb.

On some FC’s they are labeled 4v5.

The F7 in this case will not power up receivers unless it’s powered by a LiPo.
  Some FC power up receivers from the usb others won’t.
I use the F7 convertible and what your saying about RX getting power after powered with LiPo is the way it works.

-- the issue is when I connect the lipo it knocks off the USB connection. which prevents me from setting up the FC and the ECS.



Just plug in a usb and test the 5v pads to check which ones power up. There must be one 5v pad that powers up via usb.
On some FC’s they are labeled 4v5.

-- I stripped the FC and tested with USB only, I get 3.12V reading on 3V pad, and 0.12V on any 5V pad or the 10V pad. however, when I connect the lipo, all pads read correct Voltage.

I m wondering if this is a duff FC

Surprised that the designer/manufacturer of the FC did not take into account that there needs to be one 5v pad that powers up via usb for powering up the receiver.

I don’t have the exact board to test and so someone else on forum may chime in with their experience.

Connecting a LiPo shouldn't prevent connection via the USB socket or disconnect an already established USB connection. So there must be something wrong with the FC for that to be occurring. In the first instance I would certainly try re-flashing Betaflight to the FC with the "Full chip erase" option switched on but I suspect the issue is more likely to be due to a faulty hardware component on the board. Use a strong magnifying glass to check for any stray solder balls or whiskers of wire that might be causing a short somewhere on the board.

Have you tried a different micro usb connector?
I have had some finicky micro usb connectors and if you have another it’s definitely worth a try.
Scrubbing soldered area with rubbing alcohol and a toothbrush will help knock off solder balls.

thanks guys for all the suggestions. This helped me to get more determined to figure out what is going on.

I used another new HW XRotor F7 Conv. FC and I got the same issue, which obviously made me think my whole HW FCs are duff.
I know HW products cant be that bad.

So, I got another FC of different make, checked with USB connection alone, and all seems good.
this FC has the same connection to the ESC as the HW, so naturally I connected the LIPO, and then bang the FC regulator must have popped and lost the connection to BF.
similar to what the HW done.

it turned out that HW sends few cables (2 short ones) that are bundled to cover 60A ESC and 40A ESC.
mine, the 60A ESC needs specifically one of the two, the other one is meant for the 40A ESC.

I double checked and re-checked the cables and once I made sure I got the right one. all is working as expected.

One thing to note here, is hats up for HW, where the FC seems to prevent short and saved the day, unlike the other brand (more expensive that HW FC) just got fried.

so well done HW. I m a big Fan now.

(09-Feb-2022, 09:45 AM)brownviper1966 Wrote: thanks guys for all the suggestions. This helped me to get more determined to figure out what is going on.

I used another new HW XRotor F7 Conv. FC and I got the same issue, which obviously made me think my whole HW FCs are duff.
I know HW products cant be that bad.

So, I got another FC of different make, checked with USB connection alone, and all seems good.
this FC has the same connection to the ESC as the HW, so naturally I connected the LIPO, and then bang the FC regulator must have popped and lost the connection to BF.
similar to what the HW done.

it turned out that HW sends few cables (2 short ones) that are bundled to cover 60A ESC and 40A ESC.
mine, the 60A ESC needs specifically one of the two, the other one is meant for the 40A ESC.

I double checked and re-checked the cables and once I made sure I got the right one. all is working as expected.

One thing to note here, is hats up for HW, where the FC seems to prevent short and saved the day, unlike the other brand (more expensive that HW FC) just got fried.

so well done HW. I m a big Fan now.

  Other brands do the same thing and include general purpose cables and they may not match pin order of FC or 4n1 used,even when it comes as a stack.
  
 If you are using DJI be sure to check the pin order on the plug and play cable.
 They include a long cable for air unit plug in but it may not be in the correct order.
 Definitely worth checking.