Servo Twitching
10-29-2014, 12:26 PM
#1
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Servo Twitching
I have a 9303 radio & a R921 rx in a 1/4 scale cub with a Zenoah g26 engine.
All servos are fine with engine dead, But, with engine running the aileron servos
start to act nervous. They start shaking eractly. I have a ar6200x I put in the plane
and all was fine. I sent the R921 into Horizon & they could find nothing wrong but,
because they are so good at taking care of their customers, they replaced the circut
boards in the R921 & the satellite.
I put it back in the plane and it still did the same thing.
Any ideas??
Thanks!
All servos are fine with engine dead, But, with engine running the aileron servos
start to act nervous. They start shaking eractly. I have a ar6200x I put in the plane
and all was fine. I sent the R921 into Horizon & they could find nothing wrong but,
because they are so good at taking care of their customers, they replaced the circut
boards in the R921 & the satellite.
I put it back in the plane and it still did the same thing.
Any ideas??
Thanks!
10-29-2014, 10:24 PM
#2
Senior Member
The vibration is possibly at the root of your problem. The question is where and why.
I'd plug in a servo not mounted on the plane and not connected to a control surface to the channel(s) you use for the aileron servos.
If that works correctly, then the problem is likely not one of a loose connection or related to the engine's ignition.. Sometimes adding a bit of soft foam between the control surface and
what it's attached to helps.
If it turns out to be ignition related, grounding things to the battery low (negative side) may help. (Or make thing worse, for some perverse reason.)
There also are some tricks involving using capacitors on the RX power leads, Miniature ferrite cores on the servo control signal line, etc.
These are mostly trial and error, rather than following an orderly scheme.
I'd plug in a servo not mounted on the plane and not connected to a control surface to the channel(s) you use for the aileron servos.
If that works correctly, then the problem is likely not one of a loose connection or related to the engine's ignition.. Sometimes adding a bit of soft foam between the control surface and
what it's attached to helps.
If it turns out to be ignition related, grounding things to the battery low (negative side) may help. (Or make thing worse, for some perverse reason.)
There also are some tricks involving using capacitors on the RX power leads, Miniature ferrite cores on the servo control signal line, etc.
These are mostly trial and error, rather than following an orderly scheme.
Last edited by chuckk2; 10-29-2014 at 10:28 PM.
10-30-2014, 03:15 AM
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Thanks,But, I tried that very thing last night. I also put that rx in another plan with no problems. Last night I took the problem rx out of the cub & put it into another cub, first time I have tried this.
That very rx in a plane with no issues still has the twitch but only if engine is running. Rx has been mounted in foam, held in hand, had different servos plugged into port & still has this nervous twitch.
I have not tried the ground or the miniature ferrite cores, but with the problem following the rx and not staying with the plane, I'm thinking the issue is with the rx.
What's your thoughts?
Thanks for your help, it is appreciated!!
That very rx in a plane with no issues still has the twitch but only if engine is running. Rx has been mounted in foam, held in hand, had different servos plugged into port & still has this nervous twitch.
I have not tried the ground or the miniature ferrite cores, but with the problem following the rx and not staying with the plane, I'm thinking the issue is with the rx.
What's your thoughts?
Thanks for your help, it is appreciated!!
10-30-2014, 04:41 AM
#4
Does the G26 have electronic ignition?
If so you could be getting interference back-fed through a servo wire. Make sure the RX is as far away from the engine as possible and that all servo wires are as far away from the ignition leads and the battery and switch leads as possible . Try the coils as well.
If the G26 is mag ignition; what type of plug is in it?
If so you could be getting interference back-fed through a servo wire. Make sure the RX is as far away from the engine as possible and that all servo wires are as far away from the ignition leads and the battery and switch leads as possible . Try the coils as well.
If the G26 is mag ignition; what type of plug is in it?
10-30-2014, 07:42 AM
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It is a mag with a NGK BMR6A plug. The rx is away from all wires & servos.
The issue seems to be with the rx. I only say that due to putting the rx in a different plane last night that did not have a issue, now has nervous allerions, as did the plane the R921 rx came out of.
The issue seems to be with the rx. I only say that due to putting the rx in a different plane last night that did not have a issue, now has nervous allerions, as did the plane the R921 rx came out of.
10-31-2014, 01:37 PM
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I pulled the R921 rx out of the plane, after getting it back with all new electronics installed, and put it into another gas plane I have.
It did the exact same thing in both planes. So, the problem is following the receiver not the plane.
But the problem has been solved, Horizon is sending me another receiver at no charge!
HORIZON HOBBY has my vote for supplier of the year !
It did the exact same thing in both planes. So, the problem is following the receiver not the plane.
But the problem has been solved, Horizon is sending me another receiver at no charge!
HORIZON HOBBY has my vote for supplier of the year !
11-17-2014, 06:36 PM
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Thanks for the idea.
I did find and fix the problem, finally. Sad to say it was not as I thought. I thought the problem was with the Rx but it wasn't. After Horizon sent me a new rx and 2 more hours of testing and then re testing, it was in the servos. Doesn't make much sense, I took the rx out of another gas plane and switched the two and the problem followed the rx and didn't stay with the plane. I took 1 servo out & hooked up a digital servo & that stopped the other servo from its twitch. By the way, the issue was with both aileron servos. I could hook up a analog servo & they both still twitched, but put a digital one on they were solid. So, I switched both 1/4 scale servos with digital servos and NO MORE PROBLEMS ! This has been a long drawn out problem, but it's worth it. I just learned something new.
Thanks for the help !!
I did find and fix the problem, finally. Sad to say it was not as I thought. I thought the problem was with the Rx but it wasn't. After Horizon sent me a new rx and 2 more hours of testing and then re testing, it was in the servos. Doesn't make much sense, I took the rx out of another gas plane and switched the two and the problem followed the rx and didn't stay with the plane. I took 1 servo out & hooked up a digital servo & that stopped the other servo from its twitch. By the way, the issue was with both aileron servos. I could hook up a analog servo & they both still twitched, but put a digital one on they were solid. So, I switched both 1/4 scale servos with digital servos and NO MORE PROBLEMS ! This has been a long drawn out problem, but it's worth it. I just learned something new.
Thanks for the help !!
11-18-2014, 04:09 PM
#9
Just read about this in the DX-18's manual.
If the Frame rate is too fast, an analog servo may not operate correctly. You put in a digital servo and it works fine. So, ... With these two symptoms, you would need to slow down the frame rate to a rate that analog servos respond correctly. The higher speed will not work reliably with analog servos.
If the Frame rate is too fast, an analog servo may not operate correctly. You put in a digital servo and it works fine. So, ... With these two symptoms, you would need to slow down the frame rate to a rate that analog servos respond correctly. The higher speed will not work reliably with analog servos.
Last edited by Len Todd; 11-18-2014 at 04:23 PM.
