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BLS351 Servo centering problem

Old 03-06-2009, 07:49 AM
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ulfsve
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Default BLS351 Servo centering problem

Hi,

I have a 86" Yak (50cc engine class).
For this aircraft I have bought BLS351 servos for rudder and elevator.
Problem is that after installing rudder servo it will vibrate (not only making noise) when returning to center.
If I load the rudder it will disappear. I have tried with different tensin of rudder wires but it will not disapperar totally.
I have tried 3 different servos - same result.
I also tried with BLS451 and this servo did not have problem.

A servo in this price class should not have issues like this in my opinion!

What shall I do? Can they be adjusted? Other brands can be programmed to have slightly more centering tolerance.


Best Regards,

Ulf Svensson

Sweden
Old 03-06-2009, 12:57 PM
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ulfsve
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Default RE: BLS351 Servo centering problem

Hello!

Isn't any Futaba specialists here???
Old 03-08-2009, 03:32 PM
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ulfsve
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Default RE: BLS351 Servo centering problem

HELLOOOOO!!![sm=75_75.gif]

Anybody here!!!
Old 03-08-2009, 05:00 PM
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exeter_acres
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Default RE: BLS351 Servo centering problem

Bax and Krysta are in these forums on their spare time (and we are grateful!)

It is the weekend.... give them a bit....
Old 03-09-2009, 02:59 AM
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ulfsve
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Default RE: BLS351 Servo centering problem

Hi,

Sorry for my eagerness. You know what it's like when you are about to finish a new model.

//Ulf
Old 03-09-2009, 04:05 PM
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Bax
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Default RE: BLS351 Servo centering problem

The BLS-351 servo is a digital, brushless servo. The key in your case is "digital". That means that it has a very-low deadband , so it's always trying find and hold a position. With no load, the small amount of lash in the gear train, plus any flexibility in the control system, plus any mass in the control system will feed back into the servo...so you can have some oscillation when there's no load on the servo for it to sense and hold against. The small amounts of "give" in the system will constantly put pressure on the servo arm and allow a little bit of movement, which the tight deadband of the servo will try to counteract. The least that happens is the servo will buzz, but in different systems, you'll see some oscillation of the control surface.

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