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Odd servo response

Old 04-01-2020, 09:52 AM
  #1  
rayd50
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Default Odd servo response

Setting up a sailplane with the fuselage finished servos in. I was setting up the flaps. With the radio on and the Hi-Tec 7.4V D145SW flap servos plugged in all was good. When I unplug the right flap servo and plugged it back in, battery still on, it went crazy, moved to it's extreme rotation and would not move when I tried using the transmitter. Sitting there it got so hot almost burned my fingers. Same thing on the other flap servo. These are brand new out of the box servos.

Starting over with the servos plugged in then applying battery all is OK. What the heck is going on? Spectrum DX-8 radio & receiver, all operating on a 2S lipo, 7.4V.

Separate batteries one for the motor and one for the receiver/servos. Motor battery was not plugged in

The transmitter is on while all of this is going on.

The receiver is buried under the wing behind the Elevator and Rudder servos so in order to try to unplug the other Spectrum servos in the fuselage to see if the same thing would happen that would mean taking all of that apart. This 3.8M sailplane does not have ailerons.

Also not to confuse the matter, if I plug in the motor battery first, 3S 11.4V, BEC RED wire disconnected puled back under heat shrink tubing one of the fuselage servos jump to it's extreme! How is that possible, with the RED wire disconnected and the receiver battery not connected.

This is a Castle Creations, Telon 60Amp ESC, brand new out of the box.

If I plug in the 2S battery first then 3S battery and all servos are plugged in all is good! Ready to fly, but do I dare!!! Just glad I did not burn up two $60 flap servos!
Any thoughts?
Thanks.
Ray D
Old 04-02-2020, 12:05 PM
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Dick T.
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You may have to dig into fuse to have easy access to receiver and servo plugs. I would troubleshoot in the following sequence:

1. Unplug each flap servo to see if the problem persists. One servo may be defective or both are overloading the receiver bus.
2. Try another ESC. May be getting some crossover feedback from the ESC. CC Talons are great but I have known of some that burned up upon first power application.
3. If no issues show up in 1 or 2, reinsert red wire in ESC, plug in a couple of standard servos to see if all works correctly via the ESC BEC.
4. Try another receiver.
5. You might need a voltage regulator between the 2s to receiver connection. 2S vs 3S may cause some goofy imbalance.
It all has to be a trial and error. Last resort if nothing suspicious appears, try a range check and close in flight with the plug in sequence you said seems to work.



Old 04-02-2020, 12:24 PM
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rayd50
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Dick,
Sounds like good advice, I know it is not the the Hitec servos because others perform the same. I do have another 35A Talon ESC I can try, I am using a 60A on a motor that only draws 24-Amps continuous to help prevent burnout.
If I use a voltage regulator can I not just pull 7.4V off the main (motor) 3S battery and not even use a secondary 2S battery? I bought a CC regulator that I have not used yet that is adjustable.
Thank you for your input
Ray D
Old 04-02-2020, 12:43 PM
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Dick T.
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That should work. Try it first before changing out the Talon. If no joy, change the ESC. If still no joy, change out the receiver.
Old 04-02-2020, 01:30 PM
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rayd50
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Dick,
Will do.
Again thank you
Ray D
Old 04-10-2020, 05:14 AM
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jerdavis
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Originally Posted by rayd50 View Post
Setting up a sailplane with the fuselage finished servos in. I was setting up the flaps. With the radio on and the Hi-Tec 7.4V D145SW flap servos plugged in all was good. When I unplug the right flap servo and plugged it back in, battery still on, it went crazy, moved to it's extreme rotation and would not move when I tried using the transmitter. Sitting there it got so hot almost burned my fingers. Same thing on the other flap servo. These are brand new out of the box servos.

Starting over with the servos plugged in then applying battery all is OK. What the heck is going on? Spectrum DX-8 radio & receiver, all operating on a 2S lipo, 7.4V.

Separate batteries one for the motor and one for the receiver/servos. Motor battery was not plugged in

The transmitter is on while all of this is going on.

The receiver is buried under the wing behind the Elevator and Rudder servos so in order to try to unplug the other Spectrum servos in the fuselage to see if the same thing would happen that would mean taking all of that apart. This 3.8M sailplane does not have ailerons.

Also not to confuse the matter, if I plug in the motor battery first, 3S 11.4V, BEC RED wire disconnected puled back under heat shrink tubing one of the fuselage servos jump to it's extreme! How is that possible, with the RED wire disconnected and the receiver battery not connected.

This is a Castle Creations, Telon 60Amp ESC, brand new out of the box.

If I plug in the 2S battery first then 3S battery and all servos are plugged in all is good! Ready to fly, but do I dare!!! Just glad I did not burn up two $60 flap servos!
Any thoughts?
Thanks.
Ray D
Ray,

If you are using separate batteries for motor and radio, you should be using only the signal wire from the esc to the receiver. Otherwise you have a complete circuit from the motor battery through the signal and the black wire. With two batteries with different potentials can cause the smoke to escape from the system. Over volted servos can drive to one extreme, even spin 360 degrees if enough voltage is supplied.

Jerry
Old 04-10-2020, 05:44 AM
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rayd50
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Originally Posted by jerdavis View Post
Ray,

If you are using separate batteries for motor and radio, you should be using only the signal wire from the esc to the receiver. Otherwise you have a complete circuit from the motor battery through the signal and the black wire. With two batteries with different potentials can cause the smoke to escape from the system. Over volted servos can drive to one extreme, even spin 360 degrees if enough voltage is supplied.

Jerry
Jerry,
This is the first I have heard of dropping the black wire also. Even Castle noted the red wire to be dropped out nothing about the black. But rest assured I will give it a try.
Thank you
Ray D

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