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Erratic servos on initial power up

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Erratic servos on initial power up

Old 05-01-2012, 06:10 PM
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Default Erratic servos on initial power up

I have an Easy Star set up for FPV, but I am having a problem on initial start up. When I connect the battery, all of the servos start twitching and won't stop. I can remove one servo from my Rx and it powers up fine. Once powered up, I can reconnect the servo and everything works fine. I'm not exactly sure what is going on. Below is the list of equipment I am using:

DX8 Tx
AR8000 Rx
outrunner brushless motor
3S 2200mAH 25C LiPo battery (powers both FPV gear and flight controls)
Turnigy 30A ESC (5v lead disconnected)
5v/6v external BEC (using 5V)
6 servos:
rudder, elevator, 2 ailerons, 2 pan/tilt for FPV camera

Below is a video of the problem. Any help is really appreciated. I'd hate to get up in the air have the problem reoccur and lose everything.


Old 05-01-2012, 06:36 PM
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Default RE: Erratic servos on initial power up

Could the BEC be flaking out? Sounds like there is an initial current draw that is too steep for the BEC
Old 05-02-2012, 01:10 AM
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Default RE: Erratic servos on initial power up

There is still a short period of oscillation when you've disconnected the servo. I'd say that your power supply is collapsing under the start up surge current. An easy way to prove it will be to run the system from a good four or preferably five cell Nimh/Nicad Rx battery that will be able to easily provide the required current.


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