Servo twitching
 

I've just finished putting together my second Twist using the Futaba receiver and servos from the first Twist which crashed into trees. (Thats right, it crashed all of its own accord - *I* had nothing to do with it! ;))

If I actuate the control surfaces - for instance just the elevators, all the servos will twitch very slightly (not as much as when loosing signal during a range check) for a few seconds then remain still after I release the sticks. As long as pressure is kept on the sticks, they dont twitch. This is at close range, less than three feet. The twitching only occurs after moving the sticks. It wont twitch just sitting there.

I have several theories, which of these is most likely?

1) Damage from the crash - Everything works fine except for this twitching. The plane went into trees and the fuselage came out the other side into long grass, so the impact was relatively soft, and the receiver was wrapped in 1/2" foam. I've seen receivers survive much severe crashes.

2) Low battery - the receiver battery is at about 50% - would this cause twitching? I've had batteries that low before, and never noticed the twitching.

3) Interference - I'm in a room with a TV, stereo equipment and 4 computers. I've noticed interference before from the computers. (Note to self: Dont power on electric heli near computer!) I have an LT-40 with a HiTec receiver which I turned on at the same time and it didnt exhibit the same behavior as the Twist. As the twitching only occurs immediatly after the sticks are moved, I dont think its interference.

If it is crash damage, is it worth it to get the receiver repaired?

Thanks for any input!

Peter

RE: Servo twitching
 

Sounds like low voltage to me.. #2 and #3 theory are easily tested. Charge the batteries and move it away from possible interference. And if this only happens at close range it probably won't affect the plane during flight..LOL

Layne

RE: Servo twitching
 

Sounds to me like you're "Swamping"

Basically, you're just standing too close - if you back off a few feet and it goes away, no problem

RE: Servo twitching
 

I would suggest that you make sure the crystal is in place and is tight. Maybe put some tape on the receiver to hold it in place. I have seen crystals work loose during a crash and even in flight. This will also cause the chatter on servos.

Hud

RE: Servo twitching
 

I agree with Minn about the RX being "swamped" which simply means it is receiving too strong of a signal.

As for the loose crystal theory? Well I must be the odd one out here as I hear so many stories about this but have never seen this actually happen in close to 30 years of flying. NOT saying it can't happen but unlikely. I usually have to fight to get one to come out when I want it to. If your RX is/was wrapped with foam you should be fine. Most trees landings aren't that stressful on Receivers. Not too good on wings though :D.

RE: Servo twitching
 

I had a problem with my Twist and tried everything I could think of to resolve it. At one point I thought it was a problem with a servo in the tail but finally found that when I took the anntenea wire out of the tube in the fuse and taped it to the bottom of the fuse the problem went away. I figured it must have been picking up interference from the servos.

RE: Servo twitching
 

Ok I'll ask the dumb questions not to offend just to eliminate causes
1. did you ever change the channel crystal on you tx without having it retuned by a tech
2. some futaba rx's have spilt channels hi and low band so if you have one of those and changed channel in to the wrong band you can have problems being out of tune.

and as was said in one of the replys you can over power the rx by being too close.

RE: Servo twitching
 

I took the the Twist out to the field today and the twitching behavior disappered, even with the TX right next to the plane. It range checked fine so I took it up. All seemed well, so here's hoping it was simply some sort of interference in the house, or just low RX battery.

I never changed any crystals, so that shouldnt be the issue.

Peter

RE: Servo twitching
 

Is the battery a 4.8 or 6 volt? If it is 6 volt, that might be your problem. Something similar happened to me when I ran too high of voltage on my plane.

Garret H

RE: Servo twitching
 

This happens to me when my battery is close to empty. I have a 6 year old NiCD (4.8v) pack that needs replacement and is doing this to the servos unless it is fully charged.