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Afro ESC 12a SimonK - did I blow them up?

I just investigated a failure on my newly bought HK Spec FPV250.

This is what happened:
I successfully ran through my first battery, fiddled with the settings, hovered it a couple of times. All seemed great. Then I disconnected the battery and switched to the next - nothing happened. No LEDs, nothing. So I quickly disconnected everything and went home.

This is what I found out:
- If I connect the ESC without anything on the servo cable, it seems to start normal and starts beeping after a while, because nothing is connected.

- Voltage on the servo cable is exactly 5V

- Connecting the ESC to a known to function receiver. Nothing happens. ESC stops beeping, no red or green LEDs, BEC Voltage drops to roughly 2,5V

- Disconnecting the ESC from the receiver, the ESC plays the "starting sound" of three peeps in different tones.

Its exactly the same for all 4 ESCs! Are they all grilled? Or do they need to be reflashed? Any options to get them working again? They don't smell, nothing is burnt, all looks normal as far as I can tell.

Of course I can order new ones from HK, which is kinda sad, because they are roughly the price I had to pay for the whole quad... plus I need to know what went wrong, so it won't happen again!

My guesses:
- I used the very cheap power distribution that came with the quad - the ones you simply put the bullet connectors from the ESC in. Because they are not perfectly isolated, there is a slight possibility that they touched when I tried to remove the battery from the connector. I zipped it all together so it wouldn't move, but still...

- I fully connected all ESC to the KK2 board. I know that there might be problems if different BEC drive the same board. But if I understand the KK board correctly, only channel 2-6 are connected, so I must at least have one ESC still beeing intact....

Any ideas on what went wrong?

Luky for me, the KK2 still seems to be functional and the receiver is also still alive.


Rogue Drone Pilot
You're correct. The KK2 board gets power through output channel 1.

If you connect the ESCs to a receiver (even just to test) you will need to go through the calibration steps again. If you have a servo tester you can try that on the ESCs to eliminate any possibility of radio equipment and/or setting issue. Usually when an ESC dies it will spectacularly (like magic...POOF it's gone)...at least in my experiences :(
Ok thanks,
But the only problem is that the ESC included BEC will not power the receiver anymore. No matter what I connect, the Voltage gets down to about 2.5 Volt. So I can't even start to recalibrate anything...
I've seen things like this before, but usually something got very hot in the process. Specifically, I put too long of a screw into the motor on a carbon fiber frame.



Rogue Drone Pilot
Ok thanks,
But the only problem is that the ESC included BEC will not power the receiver anymore. No matter what I connect, the Voltage gets down to about 2.5 Volt. So I can't even start to recalibrate anything...
The BEC circuit may have cooked off but that doesn't necessarily mean the ESC part of it is toast. If that is the case likely your receiver isn't receiving good power as you've discovered which could be why the ESC won't start up. If I were you I would double check to see if the receiver is good. Maybe you could try a receiver battery or separate BEC to power the receiver for your test? Maybe like a four AA battery receiver pack or a known good UBEC? Heck even a full charged 1S lipo would work...
just out of curiosity I assume it is the SAME receiver the you used to test with as the one on the DRONE
I wonder if somehow the receiver is shorting / drawing to much power
as you say the power to the receiver / BEC from the ESC drops way down
what happens if the quad is powered up wired normally but with NO receiver?
I solved it by removing all +5V wires from the 4 ESC and using the BEC of a fifth ESC to power the receiver. All BECs were dead, but the ESCs still are able to drive the motors without any problems. So the quad is flying again with 5 ESCs :)


Master Tinkerer
Interesting. I'd say that you've cooked the BECs by connecting them all the the KK2, but two things... They might be linear, and not switching, in which case i't'd work fine, and of course the KK2 doesn't connect the other ESCs (besides #1) along the + rail.

Dunno. Good to hear it works now!