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Old Jan 19, 2013, 08:35 AM
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USA, TX, Grapevine
Joined Dec 2008
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Make sure you have no binding or resistance on the throttle linkage. I would suspect the servo is getting jammed up at the end of its throws with the carburetor. If you have a spring on the carb throttle arm, you need to disconnect it as the spring forces the servo to constantly fight to hold its position against the spring trying to close the throttle down. That constant fight overheats the electronics inside.

With the high performance digital servos that can cause the electronics (driver transistors) to overheat and subsequently fail. The servo is rated for 6.0v operation and normally pushing them over that with 6.6v (but it is 7.2v when charged) and when fully charged it can be way over the max servo voltage rating.

I normally use a standard servo for throttle, nothing fancy, as it doesn't need high performance nor does it usually need high torque either. In some cases with the larger gas engines a metal gear servo may be needed due to the engine and air frame vibration causing a subtle movement that can stress the throttle servo. Using a flex cable or nyrod instead of a straight length of piano wire works well too.
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