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Receiver brownout - Heli

Started by avesh, February 24, 2014, 10:52:54 PM

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avesh

I was testing my new 9650 digital servos using rcb 7x tx\rx . Servo movement is not proportional to the stick movements rather the receiver brownouts.  During the time the servo holds the last positioned and power brown out also causes them to jump. Also moving the sticks to extreme ends brownouts the receiver. Tested it on different receivers still results same. But there is an exception, testing it on tarot zyx controller no brownout occurs, everthing works fine. Zyx controller was in analogous mode. I am really confused. Help appreciated..
Planes are like feel-good buddy movies and helis are like horror films... you just have to like being scared!

anwar

Are you talking about Futaba S9650 tail servo and are you using this as tail servo ?

http://www3.towerhobbies.com/cgi-bin/wti0001p?&I=LXDTB4


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avesh

Sir I am using 9650 on cyclic powered by 60a ESC with a built in bec.. I even tried using different ESC but still it results same. Don't know why the servos are making the receiver  reach its cutoff voltage.

http://www.rcbazaar.com/products/801-avionic-25g-metal-gear-digital-servo-av9650-500-heli-cyclic-servo.aspx
Planes are like feel-good buddy movies and helis are like horror films... you just have to like being scared!

anwar

The simple reason is mechanical binding. If you disconnect the links from the servo to the swash and try moving the servos around using the TX, see if you get the same brown out.
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avesh

The receiver blinks with sudden stick movements. Is it due to servo current too high for BEC to handle and voltage drop causes brownout and receiver to reboot. The build in BEC is 3A ~5v.

I am attaching a video..

Planes are like feel-good buddy movies and helis are like horror films... you just have to like being scared!

Shannon

lol bro 3A are u kidding,a 500 requires 6A and more ur bec is not going to hold that is y the rx is having brownouts ...pls get a castle 10amp bec or hobbywing 10amp ,450 uses upto 5amp  :P
Wings are for wimps  :)-Mikado Logo/"OXY3  "/Scorpion Motors/Savox/JR PROPO/Spinblades/EDGE BLADES/KDE Direct/YEP/YGE/RJX/ GENS ACE Bavarian Demon-

anwar

Hmm, a single servo should not be causing brown-outs, especially under no load. So let us not jump the gun here.

I don't know enough about this TX/RX to say whether the blinking is just acknowledgement of TX activity or not. Having a bad servo can cause this, but we need to investigate more before we confirm.

And I am not sure where this 10A is coming from.  The basic ESC shipped with a Trex 500 has a BEC with 3A continuous and 5A burst current.

http://www.freakware.de/technik/Align/Elektronik/Regler-ESC/RCE-BL70G/RCE-BL70G_en.pdf

It is not clear what is the rated currents are for the AV9650.
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Shannon

its better to be safe then sorry 5 amp minimum for 500 ...make sure ur servos are not shorting cause this has happened before ..... castle 10amp is actually 10amp burst and 5-6 amp constant so the castle 10 amp :)
Wings are for wimps  :)-Mikado Logo/"OXY3  "/Scorpion Motors/Savox/JR PROPO/Spinblades/EDGE BLADES/KDE Direct/YEP/YGE/RJX/ GENS ACE Bavarian Demon-

anwar

We can go over specs all we want, but the focus is on identifying the problem at hand using the equipment at hand. Since this is a supplier verified combo, we need to investigate before upgrading.

Since you have 3 servos at least, the simplest is to try them one by one, and see if this blinking behaviour is there. If anyone here knows this blinking behaviour is normal, please comment. You can also test with smaller servos (9g/5g ones) if you have any lying around, and see if the blinking behavior still exists.

Even before that, how do you know it is a brown out ? The video does not necessarily convey that.
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Shannon

But anwar ji it looks like it jittered idk if u miss that so its pure brownout but y did it do that is either servo is faulty , bec is faulty ,BTW Avesh have u seperqted the RX attena 180 to 90degree apart
Wings are for wimps  :)-Mikado Logo/"OXY3  "/Scorpion Motors/Savox/JR PROPO/Spinblades/EDGE BLADES/KDE Direct/YEP/YGE/RJX/ GENS ACE Bavarian Demon-

iamahuman

A simple way to fix a minor brown out would be to use a glitch buster. Just make one and try it out.
"Chuck Norris once overcharged a lipo. Thank him for the Sun."

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JQ THE eCar.

anwar

Again... what is the glitch you are talking about ? I see the arm jumping, but it could very well be reaction to stick movements. Until we see TX stick in action, we cannot confirm if there is a glitch at all (or until the OP confirms it in the simple test case above).
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avesh

yes paried capacitor to the battery port and now every thing works fine.. The stock BEC could not handle the current drawn. Seems capacitor can counter to an extent but it will be safer to buy seperate 8A UBEC.
Planes are like feel-good buddy movies and helis are like horror films... you just have to like being scared!

iamahuman

Just for the sake of investigation, could you unplug the cap and cycle the servo at a quick rate with the motor disconnected to see if the Rx was browning out?

I do agree that the cap is a band aid solution at best. An external BEC would be ideal.

Either way, I'm glad it worked out for you.
"Chuck Norris once overcharged a lipo. Thank him for the Sun."

SSC LCG Slash 4x4.
JQ THE eCar.

avesh

#14
Yes i did the test with motor disconnected but still RX brownouts, currently paired 2x 25v 470uf capacitors and so far no issues.



Planes are like feel-good buddy movies and helis are like horror films... you just have to like being scared!

anwar

Also see if you can reroute the wires so that the signal wires are away from the high power wires (Battery to ESC and ESC to motor) as much as possible ?
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avesh

sure sir I'll do that..
thanks to all the gentlemen who helped me sorting out this issue..
cheers..

Planes are like feel-good buddy movies and helis are like horror films... you just have to like being scared!