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Servo jitters

85XJS

New member
#1
Just built the A-10 but I am getting constant jitters on both aileron servos. The elevator works fine. All servos are Tower Pro MG90.
Any one have problems like this?
 

PsyBorg

Wake up! Time to fly!
#2
Y harness that crosses the esc to motor wires? Check for any power wires crossing signal wires and if they MUST cross make sure the crossing is at 90 degrees to ensure the least amount of inductance.
 

FastCrash45

Well-known member
#3
Just built the A-10 but I am getting constant jitters on both aileron servos. The elevator works fine. All servos are Tower Pro MG90.
Any one have problems like this?
I was gonna say make sure the antenna is not close to the motors and that no power wires are crossing the antenna.
 

quorneng

Well-known member
#4
You really need to start checking things by deduction.
Firstly swap over the elevator and aileron plugs on the rx. If the ailerons still jitter then you know it is not the Rx. If the elevator now jitters you know it is either the rx or the wiring.
Then if possible test each aileron servo directly connected to the rx using external leads or better still using a servo tester. If they work normally then you know it is the wiring. If one or both still jitter then you know it is the servos.

I always keep a 2s Lipo, spare servo leads, a spare servo and a servo tester 'on the bench' to do exactly this sort of testing.
 
#5
@85XJS One other thing to consider is if it really a jitter or just the servo's straining to maintain control surface position. Did you check to make sure that your ailerons move freely? If your control surfaces are binding or require significant pressure to maintain position and if you used the hot glue method to strengthen the hinge line, you can simply take the tip of your hot glue gun and run the hot tip down the hinge line a few times to free it up.

Just a thought.
 

85XJS

New member
#7
So I ripped out the servo and found that with the servo lead and one 12" extention there is no jitter at all. Then connect it to a Y connector which is another 12" it jitters like crazy. I kept the antenna away from the wires. It seems like that extra length of wire picks up some interference. I wounder if a ferrite core would help?
 

Keno

Well-known member
#8
So I ripped out the servo and found that with the servo lead and one 12" extention there is no jitter at all. Then connect it to a Y connector which is another 12" it jitters like crazy. I kept the antenna away from the wires. It seems like that extra length of wire picks up some interference. I wounder if a ferrite core would help?
Good Idea!
 
#9
This looks like the place for me.
Will try some of the above suggestions as am having similar problems on my tiny trainer
Soon as I start to tighten up the screw gripping the rod it starts Grindr and vibrating.
Have tried FDS suggestions ,ie keeping Tx a few feet away from Rx and turning Tx on before connecting battery but to no avail.
Does it even when connecting servo directly to Rx with no y cable
 

Attachments

skymaster

Active member
#10
try letting the servo run for a bit on auto if you have a servo tester. i think sometimes they get miss align. this took care of one of mine. when you buy of if you have servo's do not play with them by moving the servo arm back and forth it will mess up the gears inside, and will mess up the timing.
 

Bricks

Well-known member
#11
try letting the servo run for a bit on auto if you have a servo tester. i think sometimes they get miss align. this took care of one of mine. when you buy of if you have servo's do not play with them by moving the servo arm back and forth it will mess up the gears inside, and will mess up the timing.

If the servo`s are good to start with this should not happen, if moving the servo arm itself causes issues with the servo then I would not trust the servo.
 

Merv

Well-known member
#12
I agree with all of the suggestions above. One more possibility, there is a limit to how may planes you can reuse your servos, they eventually wear out. I have noticed that metal gear servos wear out much faster than plastic gears, especially if you use a stabilization system. As the servo wears out, it will develop some slop (backlash) in the gears. This slop will cause the servo to become jittery. The test, hold the control surface with your fingers and stop the jitter. Then give the control surface a flick with a finger to restart the jitter.

If you can stop and restart the jitter, you have slop somewhere. It may be backlash in the servo gear, it may be in the linkage or control horns.
 
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#14
Hi
Am still getting the jitters despite trying out some of the ideas .
I have noticed it stops when the transmitter is switched off and returns when switched back on.
So I think it is probably something to do with interference from the receiver as it is very close to the y cable when fitted inside the tiny trainer.
I did try moving the wing as far away as possible from the Rx when testing,no luck.
I assume all my servos are analog so not a problem there.
Am thinking of just trying to fly it as the aerolons do work.
I don’t think it’s going to shake the thing apart.
Any thoughts are appreciated.
Thanks