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Servo jitter problems

#1
I'm just working on finishing up my edge 540 build, and I am using some 9g servos out of my older planes(they worked just fine before). For some reason when I power on everything seems to be fine, but when I move the rudder or elevator around, then return to the original position that i end up with them just oscillating around from a few degrees on either side of neutral. Another thing I found was that when I put just the slightest load on them with my finger they would work just fine. Any suggestions as to what is going on?
I am using 9g servos, 30a esc with a BEC to power all the systems, and DX6i controller and official reciever.

https://1drv.ms/u/s!Arf2yqURdBDjhgFOcBo6GOZ4Y8OZ?e=hwItHn
https://1drv.ms/v/s!Arf2yqURdBDjhgJnRJpVcCHTg7ik?e=lub1rr
 

The Hangar

Well-known member
#3
I've had similar issues, but when you think about it, you're always going to have a load on it while flying, and you'll rarely have the control surface at neutral (especially on a 3D plane!) so it's really a nonissue while in flight.
 
#4
I've had similar issues, but when you think about it, you're always going to have a load on it while flying, and you'll rarely have the control surface at neutral (especially on a 3D plane!) so it's really a nonissue while in flight.
I just checked the voltage, and that is fine. I though about that too, so I think I might just go for it and do a maiden, but first lower the throw on the tail by changing the hole on the pushrod. That way if there is a little jitter in flight, it shouldnt really be as much of a problem.
 

The Hangar

Well-known member
#5
I just checked the voltage, and that is fine. I though about that too, so I think I might just go for it and do a maiden, but first lower the throw on the tail by changing the hole on the pushrod. That way if there is a little jitter in flight, it shouldnt really be as much of a problem.
Good luck on the maiden! (y)
 

tamuct01

Active member
#6
I've heard that's common with servos operating large control surfaces. In the neutral position, there is commonly some slop or backlash in the servo horn, pushrod, and control horn. As the surface moves around in that backlash it can cause the servo to momentarily lose position and hunt for position. This can oscillate back and forth sometimes violently. When you put pressure on the surface move it away from the center, the backlash is removed and you have no issue. This video has a good explanation of what you might be experiencing:
 
#7
I've heard that's common with servos operating large control surfaces. In the neutral position, there is commonly some slop or backlash in the servo horn, pushrod, and control horn. As the surface moves around in that backlash it can cause the servo to momentarily lose position and hunt for position. This can oscillate back and forth sometimes violently. When you put pressure on the surface move it away from the center, the backlash is removed and you have no issue. This video has a good explanation of what you might be experiencing:
Ya I saw that but that exact problem is from digital servos(I think). Mine are just cheap analogs servos.
 

Aireal Anarchist

Well-known member
#8
I would sort that out before you maiden, I have had control surfaces act like that from too much gain on FPV aircraft with flight controllers and it was a real sketchy flight especially when the elevator was oscillating, fortunately I had a toggle switch to back to manual mode to stop the oscillation in flight

I know a flight controller is not your problem Im just making a point .....Im skilled and I would not fly that plane
 
#9
I would sort that out before you maiden, I have had control surfaces act like that from too much gain on FPV aircraft with flight controllers and it was a real sketchy flight especially when the elevator was oscillating, fortunately I had a toggle switch to back to manual mode to stop the oscillation in flight

I know a flight controller is not your problem Im just making a point .....Im skilled and I would not fly that plane
Deff prob the wiser way of going about things...
 

quorneng

Well-known member
#10
I feel the answer may lie in the 'old'.
A servo spends most of its time around the centre position so the variable pot wears there first which can result in both variable centring and hunting around the centre.
9g servos are cheap enough so replace to be sure.
 
#11
the only problem with replacing them is that I cant get them around where i live, unless i drive for two hours, so I have to order them, and then wait for a month for them to come in..... not ideal
 

The Hangar

Well-known member
#13
the only problem with replacing them is that I cant get them around where i live, unless i drive for two hours, so I have to order them, and then wait for a month for them to come in..... not ideal
I'd fly it then. I tend to not mind if things are super sketchy though. I know on my edge the aileron servo would jiggle when neutral but the way I fly, it's never neutral! :D