Faulty jDrones ESC?

Hello everyone!UAV/quadcopter newb here. Although not a (complete) RC/microprocessor/programming newb.Anyways, finally got all the parts needed and started assembling my arducopter this week, decided to go through all the motors and ESCs (to check and program them before assembly) and on the very last ESC i've hooked up to the receiver i got this:http://diydrones.com/video/failing-jdrones-escThe hiccups are at about 25% throttle. The jerky transition is at 50%. The fluctuations are at 75-100%. I'm pretty sure the issue is with the jDrones ESC, because:1) i've tried other motors - same deal2) i've tried this and other motors on other ESCs - works just fine3) i've tried resetting it, as well as different timings - same deal3) the ESC in question is practically soldered directly to the battery power - it's the closest one to the batt. wires on the PDB.Will try resoldering the bullet connectors on the ESC as a last resort, although they seem solid enough and jiggling them about or pressing them doesn't create any changes in the motor behaviour.And just as i was about to finally assemble the frame... *sigh*

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  • Just a tiny update...

    jDrones responded to the support ticket and are sending a replacement tomorrow, so yay! :)

    Meanwhile, i've got two 30A Hobby Wing Pentiums which i'm going to hook up to the front and rear motor, while driving the left and right with the good jDrones ESCs.

    The Hobby Wings have identical menus and settings, although the software (and hardware) quite obviously isn't exactly the same. Probably same OEM. They drive the jDrones' smaller outrunners noticeably more smoothly than the jDrones ones. I still have to check if the throttle curves / RPMs are comparable, but i'd say they are.

    If the mix proves troublesome when i get to actual flight and PID tuning, i'll revert to all jDrones ESC configuration. Especially if it turns out the input of the HW Pentiums is too filtered / response too slow. If not, i might eventually switch the remaining two jDrones ESCs for 30A Pentiums.
  • Still no response from jDrones to my support ticket...
    Not exactly the most responsive bunch, are they? ;)

    A local shop has some Hobby Wing ESCs.
    After checking the functions, specs and manuals for HW Pentium and jDrones ESCs (as well as some Alibaba.com OEM listings), i'd say they're from a same OEM, even despite the slightly different current ratings.

    Think i'll hazard buying one and checking how it behaves in place of the jDrones one.
    If things pan out - good.
    If not, i have a spare for my traditional heli, or i can get 3 more and replace all the ESCs.

    The waiting's killing me...
  • Hmmm. Additional symptom i've noticed.
    The throttle response curve on the afflicted ESC is wacky.

    It's like 0-15% throttle is linearly mapped to (very jerky) 20% RPM, then there's an exponential bump at 20-25% throttle to 50% RPM, then a linear ramp from 25%-60% throttle to about 80% RPM and then a sudden bump at 75% throttle to 100% RPM. Then a big nothing from 75%-100% throttle.

    And yes, i have calibrated it, multiple times.

    I've also noticed the fluctuations at higher RPMs don't go down, but up!
    Could this be some weird PWM frequency incompatibility?
  • Small update: resoldered the bullet receptacles and, just to be sure, the + and - wires on the PDB. Same thing. I'm running out of ideas...
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Shivchand Jaysaval liked Shivchand Jaysaval's profile
Aug 25