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Old Jun 15, 2012, 10:50 AM
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Needs to do 52 legs !!
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Hyperion DS09, DS095 and Graupner DES 428/448 for safe HP use

After having crashed a very new Avionik B09.5 some time ago i finally came acros a post from Frans-Josef on the german rc-network forum that made me smile and cry at the same time.

http://www.rc-network.de/forum/showt...=1#post2676316

He is the builder of the flying wings and knows his stuff;

http://www.franz-josef-ney-online.de/kokopelli_2011.htm

He had also 2 servo's fail in the same way as Dennis and me and he decided to investigate as to why.

He writes the reason is that the 3 legs from the potentiometer get bent 90+ degrees during production to make enough room for the motor. This sometimes makes the contacts inside the potentiometer loose from the resistance tracks. If you put some force on these loose contacts you can make the servo misbehave. It will not measure the potentiometer signal correctly. If you have such a bad servo, all you need to do is shake it or twist the case and it can stop working correctly. The fault will not always be there and you may only find out when it is to late.

You can perform a check of the servo before you glue it in. You need to remove the bottom plastic cover, pull out the motor and logic board, then you can place the motor back rotated 180 degrees. The wires are long enough, see attached picture. Now you can run the servo as normal and put some light force on the 3 legs of the potentiometer with some plastic (non conductive) tool. If the 3 pins don't move and the servo stays in the neutral position, it is safe. If the pins move
and the servo reacts, do not use this servo!!! Send it back!!!

You have been warned.



If you have a plane with these servo's already built in. Well....



Joe
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Old Jun 15, 2012, 01:34 PM
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OK, thanks, man,,, I have 5 of them, luckely not glued in yet...
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Old Jun 15, 2012, 02:58 PM
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OK, all my 5 servos 09 AMD, tested now..

2 series S050010K

2 series S090009K

1 series S030010K

ALL OK, put pressure on each pin for about 30 seconds in all directions with a toothpick.



Sebbe....

definetly worth the test, now I can sleep well, as they are going in my Viper and X.
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Old Jun 15, 2012, 04:17 PM
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Needs to do 52 legs !!
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Well done!

Hope it will save somebody a plane.

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Old Jun 15, 2012, 05:47 PM
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JJ - do you know if the makers have taken steps to correct this problem?
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Old Jun 15, 2012, 06:13 PM
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Needs to do 52 legs !!
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Quote:
Originally Posted by arcticflyer View Post
JJ - do you know if the makers have taken steps to correct this problem?
I have no idea.

Try contacting them and see what you get back.
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Old Jun 15, 2012, 09:00 PM
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SJ Propo make em,

Very interesting...
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Old Jun 15, 2012, 11:18 PM
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hate to have this happen in a low pass, there would be no recovery..

Thanks for the heads up..

Servo Hyperion Atlas Digital HP-DS 09-AMD (0 min 22 sec)
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Old Jun 15, 2012, 11:49 PM
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Quote:
He writes the reason is that the 3 legs from the potentiometer get bent 90+ degrees during production to make enough room for the motor. This sometimes makes the contacts inside the potentiometer loose from the resistance tracks. If you put some force on these loose contacts you can make the servo misbehave. It will not measure the potentiometer signal correctly. If you have such a bad servo, all you need to do is shake it or twist the case and it can stop working correctly.
I would suspect that is the same explanation for what I had observed so long ago with an inexpensive servo.While assembling the linkage the servo twitched (plugged in for linkage setup/testing).I found that when I put pressure on the servo shaft to install the servo horn screw,the shaft moved slightly down.This must have affected the pot wipers contact with the tracks.
Maybe a quick preliminary test would be to push down on the servo output shaft.
Good find JJ
Skies
Jay.
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Old Jun 16, 2012, 03:06 AM
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Quote:
Originally Posted by AirBornOne View Post
Maybe a quick preliminary test would be to push down on the servo output shaft.
Good find JJ
Skies
Jay.
i always do that....
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Old Jun 16, 2012, 11:49 AM
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This is good info Joe! Thanks for sharing.
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Old Jun 16, 2012, 04:32 PM
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nobody reacts to this more then like a few of us ? I was like: OH NOOO !!! hade to check mine right now.. If I did have some glued in my plane, I would sleep bad

There must be like 100:s out there who have this servos in fast/expensive planes..
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Old Jun 16, 2012, 05:46 PM
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Well i've checked 6 DS09AMD i had still in the box, 3 of those are about to go in an Enigma for ailerons and elevator. I noticed that the angle the legs are bent to is different between servo's.

Then there are some in a used Avionik B09 i have here, this has been flying for so long that it's probably OK. I did talk to Sergey about this and he is no stranger to bad servo's and checking them prior to laminating them in. Hope he will incorperate this check in the future.

Also, i just opened up a DS095 FMD and it's got the same issue with the potentiometer legs. So likely this servo could suffer from the same problem. Should i update the thread name?

Having said all of that, I do think these are good servo's. The quality of the parts and the layout seems better then the MKS 6100 that is now gaining popularity. It's a whole world appart from the by now historical Hitec HS-81 and HS-125 !!!

Joe
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Old Jun 16, 2012, 10:03 PM
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Who thought have thought....


Setup my Radiant F5B to go flying this morning, and just before I was about to throw it I put in some down and released the stick to neutral to check things were ok.

The elevator went down, then back to full up, then full down and sat there jumping between up and down for the next 2 mins until it stopped....

As soon as I tapped the elevator up or down and released it, the same thing happened. Wild hunting for min+ at a time.

It's a DS09SCD....

I will pull it in the next few days and have a look up the legs on the pot.
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Old Jun 17, 2012, 04:11 AM
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Needs to do 52 legs !!
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Quote:
Originally Posted by sykotic View Post
It's a DS09SCD....

I will pull it in the next few days and have a look up the legs on the pot.
Please do let us know if this is your fault and how loose the legs (or one of them anyway) is !!

Glad you found it before launch!
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