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Servo "wobble"

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Servo "wobble"

Old 01-16-2011, 08:26 AM
  #1  
D.L.R.
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Default Servo "wobble"

Have had a wing and complete horizontal/vertical stabilizer lying around for a few years and decided to connect them and at least try to come up with a functional and fun plane to fly, not concerned about appearance, just want it to be fun. Finished it up last nite and almost happy with it, looks a bit like a REAL Ugly Stik. Airfoil parts are from a Telemaster 40 and has flaps. a couple days ago I hooked up the Rx to the battery and checked out all movements, reversed, set EPA, HI/LO throws etc. Everything worked fine. Last nite after weighing (6.5 lbs.) and balancing, I double checked throws etc. everything ok BUT for some reason when the ailerons come back to neutral they wobble, it's not a sharp movement, looks like if you were flying the plane would wave at you, really weird. The ONLY thing I did between the first (everything worked fine) and second time (ailerons wobble) was charge the batteries (which I then checked voltage under load). Radio is a well used Futaba T6EXA with S3004 servos. The receiver is not the original (came with with a cheapy 4 channel Futaba I bought a couple years ago), 4channel Tx, 8 channel Rx 127 something, not handy to check right now.
Any ideas as to what happened ????
Thanks, Dan
Old 01-16-2011, 09:57 AM
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pkevinb
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Default RE: Servo

I think that is what happens when the pots go bad.
Old 01-16-2011, 12:13 PM
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D.L.R.
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Default RE: Servo

Thanks pkevinb,
After my post I double checked that RX matches TX and they came together when purchased in 2002 and had lots of hours on them with no problem, RX is FP-R127DF 7 channel. POTS is what, potentiometer ? I'm not real knowledgeable on electrical stuff.
Thanks again, changing servo is definetly going to happen, just trying to understand howcome.
Dan
Old 01-16-2011, 01:33 PM
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pkoury
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Default RE: Servo

That is usually caused by dirty connections. Try plugging and unplugging all connections to ensure good continuity. Low voltage to the servo due to increased resistance caused by a poor electrical connection does not supply the servo with enough power to work right.
Old 01-16-2011, 03:00 PM
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TedMo
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Default RE: Servo

Your problem may be simply that you are too close to plane and with newly charged bat. are overloading RX.Of course the old servos may be it.
Old 01-16-2011, 03:26 PM
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N1EDM
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Default RE: Servo

Also, if you have fluorescent lights in the area, they throw off some mild RF that might be causing a problem, too.

Just my $.02

BOb
Old 01-16-2011, 06:13 PM
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D.L.R.
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Default RE: Servo

Thanks folks, I like the idea of poor continuity, altho it was ok a few days before, no fluorescent lites and I did try different distances when problem first noted. I WILL be looking real close at the connection issue in the next few days, that does make sense after the wing hung in the rafters for so long with servos in it.
Thanks again.
Dan
Old 01-16-2011, 06:57 PM
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lejongleur
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Default RE: Servo

Dan - these other issues are possible, but your setup really shouldn't exhibit this kind of behavior - and bear in mind its potentially fatal to the plane. Unless you are sure that you find and completely fix some obvious error I would say replace the servo - they are pretty cheap nowadays.

Hope this helps...Chris
Old 01-17-2011, 10:05 AM
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CWDoherty
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Default RE: Servo

I had the same problem turned out to be a badly pinched wire causing a major voltage drop to the servo. i cut out the pinched section of wire, resoldered and it was good to go
Old 01-17-2011, 10:14 AM
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ScottMcM
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Default RE: Servo

I had the same issue a while back. Turned out to be a bad/dirty connection. Cleaned it up and it worked as it should.
Old 01-17-2011, 06:37 PM
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D.L.R.
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Default RE: Servo

Ok, this is a little embarassing but I think I found the problem thanks to all the input from you guys. You have to realize I'm 71 years old and my "lookers" don't work as well as they once did !!!
It was just hard to believe there would be anything major causing this problem, so with a bright lite and STRONG readers I started looking closely at the plugs, a new 8 inch extension in the reciever, the female in the reciever and the male servo wire plug . As I said before the wing had hung in the rafters for awhile, and I found a gob of fly poop on the male servo connector. I don't know how other radios are (mine back in the early 70's were KRAFT and I don't recall how they were either) but the FUTABA has an open area on one side of the male servo plug and the 3 wire connectors are exposed and that's where the gob of fly poop was. My "airplane shop" is in the basement, and with the humidifier on the furnace maintaining about 60% humidity I'm assuming the plug shorted out at that point. Anyway, after some cleaning with alcohol both outside and inside (with a very small pointed piece of balsa) and allowing to dry, it worked like new !!!!
I really was prepared to change the servo, but the way I put it in when I built the plane there is no easy access. I want to thank you all for your input, even tho you didn't tell me fly poop was the culprit (who would have guessed) !!!!!!!!!!!!!
Dan
Old 04-01-2011, 09:35 AM
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D.L.R.
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Default RE: Servo

Just a question, since I look at RCU quite often (nosy and curious as to whats new) I run into the few posts I have made and received answers or opinions on. After MY problem or question has been answered or solved I assume getting rid of all the questions/answers in the entire post would be the right thing to do. IF I am correct in my assumption, can someone tell me HOW to do it ???
Dan
Old 04-01-2011, 12:10 PM
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mustangman177
 
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Default RE: Servo

Leave them.... Someone else will learn from your experience with this issue.
Old 04-01-2011, 03:10 PM
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garylynn
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Default RE: Servo

dirty pots on the tx, move the sticks rapid back and forth 20 or so times to help the contac. had that happen only with my ailerons and almost sent the tx back to futaba for repair!!
Old 04-02-2011, 04:27 PM
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cl0ckwork
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Default RE: Servo


ORIGINAL: D.L.R.

Just a question, since I look at RCU quite often (nosy and curious as to whats new) I run into the few posts I have made and received answers or opinions on. After MY problem or question has been answered or solved I assume getting rid of all the questions/answers in the entire post would be the right thing to do. IF I am correct in my assumption, can someone tell me HOW to do it ???
Dan
Try editing your original post, put something like this


EDIT
time/date stamp

Ifound the asnwer it was ________. Remember to always check _________.
Old 04-02-2011, 05:24 PM
  #16  
D.L.R.
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Default RE: Servo

Thanks for the input guys, after reading some posts on other subjects I guess the answer from mustangman177 does make sense, I've found answers to questions or at least an area to look into on other issues in the past from some pretty old posts. A new response by garylynn on April 1st wasn't even something I had considered, and who knows, maybe after I cleaned up the servo contact and tried again and it worked MAY have been because I had worked the TX stick the number of times it took to "shine" up the TX pots and that was the real problem ???????? So I guess we'll just let it go until it disappears. Thanks again.
Dan
Old 09-06-2011, 07:50 PM
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D.L.R.
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Default RE: Servo

First I was sure the servo "wobble" was taken care of and didn't need to worry about it and in fact DIDN'T worry about it and had many fun flights, even increased engine size from .36 to .46. Then about a week ago a roll with rudder/elevator/ailerons in use was about to come to an end when it got REAL sloppy before returning to straight and level. Could NOT determine what happened, flew some more, landed, checked aileron servo (I felt that was the problem) but found nothing wrong. Fueled up took off and had some more fun when BAM no ailerons, fortunately they just stayed flat and didn't move. Brought the old girl back utilizing rudder (scared to use the ailerons 'cause I now KNOW they have a problem). Changed servo and extension, no problem since. disassembled the servo saw nothing wrong but can guarantee no one will ever use it or the extension again. SOOO, backing up to 17 Jan 2011 I must say to lejongleur you were 100% right and I really dodged the bullet on this one UNFORTUNATELY if I had changed out the servo/extension then I probably would have wound up using them again somewhere later and the possibility of someone or something being injured would certainly have been possible. I SHOULD HAVE LISTENED TO YOU, YOU WERE RIGHT !!!!! Thank you.
Dan

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