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-   -   servo slow and stuttery on 1 side only. (http://www.Wattflyer.com/forums/showthread.php?t=72872)

DHC Beaver 12-29-2013 05:16 AM

servo slow and stuttery on 1 side only.
 
I have a very weird problem.I'm setting up the servos in my Nieuport 21 wing.The right servo works at normal speed up,but slow and stuttery moving back to neutral,and on down movement and return.The left servo does this both up and down.
The setup is this:
Turnigy 9x with er9x fw,Frsky 4ch rx.The servos are HK15168's,as they were the only ones small enough to fit in the wing.Rx power is through the esc's ubec.
I'm stumped.Is this a rx,tx,servo,esc,or whatever problem?
Thanks for any help,guys 'n gals.

CHELLIE 12-29-2013 05:38 AM

check your control surface hinges, make sure they are not to stiff, that puts a lot of stress on the servo if they are to stiff, disconnect the servos from the control surfaces and test them with no resistance on them, if the servos still act funny, you may have a bad servo, replace the servo thats acting up, if that does not correct the problem, there may be a problem with a loose connection between the receiver and servos. hope that helps, Chellie

hayofstacks 12-29-2013 05:54 AM

x2. lots of ca hinges do this.

fhhuber 12-29-2013 07:22 AM

Check the connections between the servos and RX. A marginal connection can give some very odd results.

Corrosion on the pins of an extension, not being fully plugged, a wire starting to fail... Anything that gives less than full connection between RX and the servo.

kyleservicetech 12-29-2013 09:06 PM

Quote:

Originally Posted by DHC Beaver (Post 935464)
I have a very weird problem.I'm setting up the servos in my Nieuport 21 wing.The right servo works at normal speed up,but slow and stuttery moving back to neutral,and on down movement and return.The left servo does this both up and down.
The setup is this:
Turnigy 9x with er9x fw,Frsky 4ch rx.The servos are HK15168's,as they were the only ones small enough to fit in the wing.Rx power is through the esc's ubec.
I'm stumped.Is this a rx,tx,servo,esc,or whatever problem?
Thanks for any help,guys 'n gals.

Just to check on your servos, have you tried running your servos with the pushrods disconnected from the servo?

If the problem still exists, either your servos are kaput, or you've got receiver battery supply problems. That could be checked by substituting a standard 4 cell Nih 4.8 volt battery pack on your receiver. Be sure to unplug your ESC from the receiver so the ESC's BEC and the battery don't argue with each other.

Or maybe even the radio itself????

rcers 12-29-2013 09:18 PM

Agree with above - if the servo runs funny with no load - it is the POT causing the issue. That is something good servo manufactures will cover under warranty - not sure about HK. They are hit and miss, and mostly miss (in my book).

Mike

kyleservicetech 12-30-2013 01:54 AM

Quote:

Originally Posted by rcers (Post 935519)
Agree with above - if the servo runs funny with no load - it is the POT causing the issue. That is something good servo manufactures will cover under warranty - not sure about HK. They are hit and miss, and mostly miss (in my book).

Mike

Yeah
All of my models have name brand servos in them. Mostly Hitecs. I did have a Futaba high power servo get erratic several years ago on a flap servo. It showed up before takeoff, so no damage done.

A couple of years ago, a fellow club member had a Hitec servo lose centering on the aileron of a $$$$ wet turbine model. He is a very good pilot, and got the jet back on the ground in one piece. Didn't take long to figure out what happened to the servo. The servo Arm was from a different brand servo. The splines didn't match up, and the different brand servo arm was slipping on the Hitec servo shaft.

Word to the wise.

DHC Beaver 12-30-2013 02:47 AM

Thanks for your replies, people.I did some further investigating,and tried the following:
Replaced servo with brand new Futaba.same problem.
Changed battery pack to 4cell ni-mh pack,direct to rx.no change.
Replaced receiver ,no change.
Tried transmitter with a different wing plugged in to current model.No problems at all.This means it's definitely not the tx,or the model settings.I'm going to try one more rx tomorrow,as i don't have it here at the moment.
Will report back in due course.

Larry3215 12-30-2013 04:21 AM

In that case Id say you definitely have a linkage or hinge problem of some kind causing binding or extra resistance.

Do as the others have said and unhook the linkages and move the surfaces by hand to check for binding, stiffness etc.

You might also eyeball along the hing line to see if the wing is warped. If the hinge line is NOT straight it can cause the surfaces to be difficult to move for part of the travel then it might get easy again but hard to return to center.

Good luck!

DHC Beaver 12-30-2013 04:34 AM

Thanks for that,Larry,but i forgot to mention i actually removed both servo's from the wing.I flexed the ailerons up and down to make sure there was no binding.Btw.,Larry,having a ball with my Capricorn,thanks for a wonderful design!:cool:.

Larry3215 12-30-2013 05:04 AM

Im at a loss for other possibilities for the problem then.

Hmmm - are you using servos with enough torque? What size model is this? Maybe post some pics of the setup. perhaps something will jump out.

fhhuber 12-30-2013 05:41 AM

Generally these turn out to be a bad connection. That may or may not mean a bad solder joint in the RX, bad crimp in n extension, corrosion on one or more pins of a plug...

I got similar results from an extension that wasn't fully plugged in. Got it pushed together right and the issue was gone. Still gone after 4 years of flying the plane.

Lots of places for it to have an electrical fault and they can be VERY simple... or VERY hard to find.

Flyer495th 12-30-2013 02:48 PM

If you are using a y connector swap it out

kyleservicetech 12-30-2013 08:58 PM

Quote:

Originally Posted by fhhuber (Post 935563)
Generally these turn out to be a bad connection. That may or may not mean a bad solder joint in the RX, bad crimp in n extension, corrosion on one or more pins of a plug...

I got similar results from an extension that wasn't fully plugged in. Got it pushed together right and the issue was gone. Still gone after 4 years of flying the plane.

Lots of places for it to have an electrical fault and they can be VERY simple... or VERY hard to find.

Good point.

I've found one or two cases over the years where the female pin of the servo extension cable had virtually zero contact pressure when it was connected to a mating connector. If you've got an old junk servo cable, pull the male pin out of it, and slide that male pin into the female pin, one pin at a time.

There should be several ounces of pressure required to push the male pin into the female pin. Make certain the "Square" pin is horizontal while checking. If the pin is rotated by 45 degrees during testing, that could give a false impression of the female pin being tight enough.

fhhuber 12-30-2013 09:09 PM

A step in diagnosing what is going on:
You can "tweak" a slight curve into the pins to "improve" contact.
This will make a flaky connection somewhat resistant to vibration.

This is not a real fix, since all that it will do is prove is that you need a new connector, because if this seems to cure the issue the connector is failing.

You can fly this way for a while with small, relatively low performance aircraft. But should replace the extension (usually its an extension that is bad when this helps) ASAP.

For large or high performance models the current capacity of the connection will not be adequate for high torque servos under flight loads.

Larry3215 12-30-2013 11:00 PM

Quote:

Originally Posted by fhhuber (Post 935563)
Generally these turn out to be a bad connection. That may or may not mean a bad solder joint in the RX, bad crimp in n extension, corrosion on one or more pins of a plug...

I got similar results from an extension that wasn't fully plugged in. Got it pushed together right and the issue was gone. Still gone after 4 years of flying the plane.

Lots of places for it to have an electrical fault and they can be VERY simple... or VERY hard to find.

+1

DHC Beaver 12-30-2013 11:19 PM

Fixed it.Woohoo!
It turned out to be something i'd done in setting up the model in the tx.
I deleted the model,and made a new one.Problem solved.
Unfortunately,I don't know exactly what I did in the programming that caused it.I should study the er9x manual more thoroughly.There are so many options,it gets a bit challenging for an old dumb dutchman:D.
Thanks for your efforts folks,much appreciated.
Hans.

kyleservicetech 12-31-2013 12:55 AM

Quote:

Originally Posted by DHC Beaver (Post 935661)
Fixed it.Woohoo!
It turned out to be something i'd done in setting up the model in the tx.
I deleted the model,and made a new one.Problem solved.
Unfortunately,I don't know exactly what I did in the programming that caused it.I should study the er9x manual more thoroughly.There are so many options,it gets a bit challenging for an old dumb dutchman:D.
Thanks for your efforts folks,much appreciated.
Hans.

Thanks for the update!

That's why writing the software for these microcontroller controlled devices such as our RC radios can be a real challenge. It is nearly impossible to physically program in every possible combination of settings and functions to verify proper operation in all of them.

The number of combinations quickly gets into the "Gazillions!".

Larry3215 12-31-2013 01:09 AM

Quote:

Originally Posted by DHC Beaver (Post 935661)
Fixed it.Woohoo!
It turned out to be something i'd done in setting up the model in the tx.
I deleted the model,and made a new one.Problem solved.
Unfortunately,I don't know exactly what I did in the programming that caused it.I should study the er9x manual more thoroughly.There are so many options,it gets a bit challenging for an old dumb dutchman:D.
Thanks for your efforts folks,much appreciated.
Hans.

I kind of doubt thats what fixed it.

I dont know of any programming options that will cause one-sided slowing like that. The few radios that do allow you to control servo speed make things slow down both ways at the same time as far as I know.

I think it more likely you did have a connection problem and re-installing the servos or jiggling the model "fixed it" - at least temporarily.

If it was the tx causing the issue, it would have shown up when you tried testing the other wing and Futaba servo.

Its also possible your tx is having an intermittent problem - perhaps with the pots on the sticks.

I would watch things carefully for a while just to be safe.

Good luck!


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