UBEC Failure

[BrianG]

I was out playing at the track yesterday with my MBX5/Corr truck, and things were going pretty good... until I landed a jump really hard upside down. Well, the zip tie holding the MMM broke causing one of the motor leads to come undone. The Koolflight BEC apparently didn't like something about that and decided to blow. Unfortunately, it also took out my Futaba S9155 steering servo. And my Spektrum receiver won't power up anymore either. Poo.

When I got home last night, I opened the servo; yup, it's gone. About the only thing it is good for is having an extra servo case.

And hooking up the UBEC to my PS just made it get VERY hot VERY fast while outputting full input voltage.

Expecting the worst, I then opened up the Spektrum, but curiously did not see any visible damage. Now, that doesn't necessarily mean anything, but I started dissecting the unit further anyway. There is what looks like a regulator before the actual Spektrum circuitry, so maybe it's not dead after all? A little continuity test between all the servo pins showed that the ground trace was blown (couldn't see it as that trace is apparently sandwiched). So, I soldered a resistor lead as a bridge across the all the - pins, and for good measure, another across all the + pins (on the solder side of the PCB). Hooked her up and she lives! Yay! That saved me ~$80. So, it looks like the regulator saved the Spektrum circuits from overvoltage after all.

Just thought you guys might want to know this if it happens to you...