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Servo not centering

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Servo not centering

Old 02-21-2007, 05:27 AM
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SuperAirborne
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Default Servo not centering

Hi All!

Yesterday at the field I experienced a strange phenomonen. On my first flight, the elevator trim was completely out; I had to give up elevator trim about 12 clicks to get the plane to fly level. (I did not change the cg of the plane, also I have digital trims on my Tx).

On the fourth flight of the day, suddenly the elev trim changed again, this time rocketting the plane upwards. Again I had to retrim, this time about 10 clicks down. I landed immediately.

I inspected the plane for a slip in the linkage, which I couldn't find. The I noticed that when I gave up elevator and release the stick the elev would centre and then jitter or flutter around that position for about 5 seconds b4 being still.

Could it be that the servo doesn't know how to centre anymore?? The servo is between 3-5 yrs old. Any ideas?

Thanks
Old 02-21-2007, 10:39 AM
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Rodney
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Default RE: Servo not centering

You did not by chance use a different brand of servo arm than the servo is did you. You can not mix servo arms on some servos. On standard servos, Hitec, Appolo and Hobbico are interchangeable and Futaba, DAD, GWS, FMA and Tower Hobbies are interchangeable but you can not mix any of two groups without slippage or fit problems. Alsom ake sure you did not use a metric threaded push rod on a 2-56 coupler or visa versa.
Old 02-21-2007, 10:53 AM
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daveopam
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Default RE: Servo not centering

Could be a bad servo. Could also be a bad extension or "Y" harness if you used one. I would not fly the plane with it in there till you find out.

David
Old 02-21-2007, 02:52 PM
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deckerv
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Default RE: Servo not centering

The pot on the servo is probably going bad. It's probably better off replacing it rather than trying to fix it.. Keep the old one for parts (gears).
Old 02-21-2007, 05:38 PM
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Default RE: Servo not centering

usually a dirty wiper on the pot causes centering problems.that is one reason kraft went to carbon button wiper way back when.now with sealed pots and all best to replace it.only other thing could be a stripped gear you could inspect them to see if any missing or damaged teeth.
Old 02-22-2007, 03:27 AM
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SuperAirborne
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Default RE: Servo not centering

Thanks for the replies guys!

I think the pod on the servo has bone bad! I connected the servo up through a y-lead yesterday and added another servo to the channel. The new servo showed no problems, however the one installed in the plane (JR539) had serious difficulty centering. I guess I'll replace it before my next day at the airfield.

Another question: Can all Rx's and servos operate on 6volts? I mainly use JR equipment.

Thanks so much!
Old 02-22-2007, 09:35 AM
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TLH101
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Default RE: Servo not centering

Make sure there is no corrosion on the connector. A dirty connector will some times cause 'hunting" around the center. Sounds like a bad servo, but check that connector, to be sure.
Old 02-22-2007, 07:00 PM
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Default RE: Servo not centering

most newer equipment can operate on 6 voltsmost servo specs showed both 4.8 and 6 volt specs at one time as there is an increase in performance at the higher voltage.

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