Servos jumping on startup    Gallery
View related threads: (in this forum | in all forums)

Logged in as Guest



Users viewing this topic: none
    Search This Thread  
 
Printable Version


Hangar 9 Ultra Stick Lite ARF - 120/ Saito 180 - RTF
Seller:  Hill202
Details:   $500.00   |  5/14/2013   |  Classified Ad
We will rotate YOUR AD in this spot if you select "Forum Featured" when placing or editing your ad!

All Forums >> RC Airplanes >> Questions and Answers >> Servos jumping on startup
Page: [1] 2   next >   >>  

Tower Hobbies Get Coupon Codes Brands  
Login
Message << Older Topic   Newer Topic >>
Servos jumping on startup - 8/13/2012 12:51 AM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline 		I have just installed some Savox digital servos in my new 26% MXS-R with a Spektrum AR7000  and DX8 and I'm experiencing every servo jumping to full travel briefly before centering themselves. Any idea what's causing this, and if there's anything I can do to make it stop? These servos are high-torque and I'm concerned that they may be over-stressing the joints and linkage when they do this (honestly, I'm not positive they're jumping to full servo travel - it may be that they're only cycling full programmed travel). I have re-bound the receiver to the model after setting the travel in the radio as per Spektrum's instructions, but it didn't stop this from happening.

Although I can't swear to it, I think I've experienced similar behavior in the past with my other planes, but most of them only used standard-type analog servos, so it wasn't anything to worry about.

Thanks in advance, guys!


Hide Signatures
       Post #: 1

RE: Servos jumping on startup - 8/13/2012 1:53 AM   
Steve Percifield


 

Posts: 943
Score: 108
Joined: 2/19/2002
Last Login: 5/19/2013
From: Noblesville, IN, USA
Status: offline 		I don't know the reason, but have the same thing happen on occasion myself. It doesn't seem to matter what brand of receiver or servos. Since it's so brief, as long as it doesn't break any linkages, there is no harm done. I just make sure everything works normally after power up.


_____________________________

Sir Percy
Hoosier Dawn Patrol

Hide Signatures

(in reply to 7kings)
       Post #: 2

RE: Servos jumping on startup - 8/13/2012 2:01 AM   
guver


 

Posts: 14841
Score: 174
Joined: 3/7/2003
Last Login: 5/16/2013
From: LaGrange, OH, USA
Status: offline 		Ya know. I fly a dozen or so on a regular basis and MOST of them do this. One of them (my e-stik) never does unless I had moved a surface of course. Something to ponder why. My newest plane the millenium master seems to be the worse where it swings the servos fast and far upon EVERY powerup.

_____________________________

and airplanes were in

Hide Signatures

(in reply to Steve Percifield)
       Post #: 3

RE: Servos jumping on startup - 8/13/2012 2:07 AM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline 		It wouldn't bother me if it was just a little jump, but it's a big swing and fast every time I power it up.


Hide Signatures

(in reply to guver)
       Post #: 4

RE: Servos jumping on startup - 8/13/2012 2:08 AM   
SeamusG



Posts: 3919
Score: 199
Joined: 6/16/2007
Last Login: 4/10/2013
From: Arvada, CO, USA
Status: offline 		I use 4 AR7000 and 3 AR6200 with my DX7, servos are JR DS821 & Hitecs (various analog standard servos) and I don't recall any of them behaving the way you describe. Most batteries are 6.0v but 2 are still 4.8v.

Just to make sure - power up Tx then Rx. The AR7000 has fail safe logic for when there is no Tx connected. I can imagine that during start up, if it doesn't sense the Tx that its fail safe logic might take a "big swing". Just thinkin' out loud.

Oh, and all of mine have been sent back to Horizon Hobby for available firmware upgrades.



Hide Signatures

(in reply to guver)
       Post #: 5

RE: Servos jumping on startup - 8/13/2012 2:12 AM   
scale only 4 me



Posts: 7642
Score: 314
Joined: 1/29/2002
Last Login: 5/19/2013
From: Avon Lake, OH, USA
Status: offline 		Mine (Futaba equiptment) moves a little sometimes, but never full travel like the OP reports,,

Hide Signatures

(in reply to guver)
       Post #: 6

RE: Servos jumping on startup - 8/13/2012 4:31 AM   
Gray Beard


 

Posts: 12542
Score: 314
Joined: 4/21/2003
Last Login: 5/18/2013
From: Hemderson, NV, USA
Status: offline 		A little clattering around when I turn on a plane with a fully charged pack but the only plane I have ever had that tossed them full throw was an electric?

_____________________________

Drinking and driving are illegal, why do bars have parking lots
Daisy Air Guns, keeping kids off your lawn for 100 year

Hide Signatures

(in reply to scale only 4 me)
       Post #: 7

RE: Servos jumping on startup - 8/13/2012 4:41 AM   
speedracerntrixie


 

Posts: 2370
Score: 189
Joined: 6/7/2010
Last Login: 5/19/2013
From: San Jose, CA, USA
Status: offline 		On my Spektrum stuff I always do a re-bind once everything is all hooked up. I have not expereinced this to the same degree as you but what I have seen in my equipment usually goes away after the re-bind.


Hide Signatures

(in reply to 7kings)
       Post #: 8

RE: Servos jumping on startup - 8/13/2012 12:03 PM   
jetmech05


 

Posts: 3920
Score: 133
Joined: 7/12/2005
Last Login: 5/19/2013
From: Jacksonville, FL, USA
Status: offline 		Stupid thing to ask but here goes...you are turning on the transmitter first, then the plane?
My large scale Futaba system with Hitech servos does not do this. Can you insert any other brand of servo into this receiver to see if it is the receiver or the servos causing this? Don't plug into an empty port, unplug a servo from a port that is jumping

Hide Signatures

(in reply to speedracerntrixie)
       Post #: 9

RE: Servos jumping on startup - 8/13/2012 12:13 PM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline 		Not a stupid thing to ask - yeah, I always fire up the TX first and give it time to initialize before turning on the RX. I can try another type of servo, but I don't have any other digital high-torque servos to compare against.

I'm going to measure the throw today and see if they're going to full-stop or if they are only going to fully-programmed travel. Like I said - the annoyance I can live with, but the threat of damage I can't...

Now that I'm thinking about it - I do seem to remember the flaps of my P-47 (RIP...) doing the same thing upon RX initialization. They would drop full swing for a second, then go back up.



Hide Signatures

(in reply to jetmech05)
       Post #: 10

RE: Servos jumping on startup - 8/13/2012 12:18 PM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline
quote:

ORIGINAL: speedracerntrixie

On my Spektrum stuff I always do a re-bind once everything is all hooked up. I have not expereinced this to the same degree as you but what I have seen in my equipment usually goes away after the re-bind.



At first I thought it was just the failsafe settings not being properly set, but I've since re-bound half-a-dozen times.



Hide Signatures

(in reply to speedracerntrixie)
       Post #: 11

RE: Servos jumping on startup - 8/13/2012 2:05 PM   
BarracudaHockey



Posts: 18350
Score: 280
Joined: 7/13/2003
Last Login: 5/17/2013
From: Jacksonville, FL, USA
Status: offline 		Power is reaching the servos before a signal. Some servos react to it, some stay put.

_____________________________

Andy - Helicopter Forum Moderator
AMA 77227 Leader Member- Contest Director
www.JaxRC.com

Hide Signatures

(in reply to 7kings)
       Post #: 12

RE: Servos jumping on startup - 8/13/2012 2:08 PM   
drzidli


 

Posts: 2
Score: 100
Joined: 12/5/2010
Last Login: 5/19/2013
From: , UNITED KINGDOM
Status: offline 		When the Rx is turned on it takes a couple of seconds to connect to the Tx.  During that period it has no servo position info so until it connects the Ar7000 and other Spektrum//JR receivers are supposed to issue the failsafe positions  (to all but throttle) as established at bind time. 
Some of them don't. Instead they issue a spurious very brief signal and then nothing until it connects. This results in servos typically being driven around 30 degrees until connection is made then they assume the Tx commanded position.  Very annoying when it operates a retract switch or similar. 

For some reason, all analogue servos I tried were afffected but digital ones (DS811, DS821,DS8231) were not.  Hence the problem can often be circumvented by moving to a digital servo, though I note you have digital servos in this case.  

To test this you can power on the Rx without the Tx.  If you can move the servos then there is no signal.  I had two AR500s and 4 RD921s with this problem.  The distributors replaced them - eventually, as they seemed not to (want to) understand what the problem was. 

Hide Signatures

(in reply to 7kings)
       Post #: 13

RE: Servos jumping on startup - 8/13/2012 2:43 PM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline 		The servos are definitely being driven at this point. After the initial unexpected deflection and return to neutral, the digital servos will hold their position and refuse manual movement.


Hide Signatures

(in reply to drzidli)
       Post #: 14

RE: Servos jumping on startup - 8/13/2012 2:46 PM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline
quote:

ORIGINAL: BarracudaHockey

Power is reaching the servos before a signal. Some servos react to it, some stay put.


I hear you. I'm only concerned if they deflect far enough to over-stress the linkage and joints (which I hope to measure in a couple hours). If that's the case, I'm going to need to fix something. If I recall correctly, the AR7000 also supports a manual fail-safe configuration - I may try that next to see if that helps.



Hide Signatures

(in reply to BarracudaHockey)
       Post #: 15

RE: Servos jumping on startup - 8/13/2012 5:09 PM   
tony0707


 

Posts: 767
Score: 115
Joined: 7/7/2006
Last Login: 5/14/2013
From: Inverness, FL, USA
Status: offline 		Hi
I was always taught to turn on the RX first then the TX
YOu can tell if someone is on your frequency by doing it this way
I fly only 72 mh
Flight done RX off first then TX
You might be experiencing the residual battery charge being a bit higher than the true batterys rating -that gets used up rather quickly when the battery is on for moments after being turned on
Not a problem if servos only do move that way at first then resume normal use

_____________________________

" The power and performance glo fuel , 15 % Morgan Omega "

Hide Signatures

(in reply to 7kings)
       Post #: 16

RE: Servos jumping on startup - 8/13/2012 5:37 PM   
SeamusG



Posts: 3919
Score: 199
Joined: 6/16/2007
Last Login: 4/10/2013
From: Arvada, CO, USA
Status: offline 		Tony, voltage has very little to do with servo arm movement (speed and torque - yes).  The pulse sent to the servo that controls arm movement is one of "sufficient" voltage for a very specific length of time. If the pulse is .1 ms then the servo arm is positioned at one extreme. If .2 ms long then the arm is positioned at the other extreme. To oscillate between both extremes and then center would suggest multiple pulses being sent from the Rx to the servo - one very short, one very long then one of precisely .15 ms which centers the servo arm.




Hide Signatures

(in reply to tony0707)
       Post #: 17

RE: Servos jumping on startup - 8/13/2012 6:00 PM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline 		In terms of the sequence of start-up, I was always taught to start your TX first to ensure that the RX was always receiving a control signal. Of course, it shouldn't make much of a difference with this technology, though, as the RX should go into Spektrum's Smart Safe mode if it doesn't detect a TX. In this situation, it doesn't matter whether the TX is on when the RX is fired up; the behavior is the same.


Hide Signatures

(in reply to SeamusG)
       Post #: 18

RE: Servos jumping on startup - 8/13/2012 6:10 PM   
SeamusG



Posts: 3919
Score: 199
Joined: 6/16/2007
Last Login: 4/10/2013
From: Arvada, CO, USA
Status: offline 		Just got off the phone with Horizon support (aka Spektrum among others). They said that this behaviour in not uncommon with "bindable" Rx. In the cases that they have been presented with the problem, re-binding the Tx / Rx solved this deflection problem 97% of the time. The other 3% were Rx problems. Also, there is an upgrade to the AR7000 having to do with the time it takes for the Rx / Tx to reconnect following a lost signal. Original one's took maybe 4-5 seconds to reconnect. Upgraded models take something over a second.

HTH


Hide Signatures

(in reply to 7kings)
       Post #: 19

RE: Servos jumping on startup - 8/13/2012 6:13 PM   
oliveDrab



Posts: 392
Score: 105
Joined: 2/16/2005
Last Login: 5/19/2013
From: Christoval, TX, USA
Status: offline 		I have a Bearcat with 7 Hitec servos. I always turn on Tx first, then Rx - always. Out of those 7 servo's only one reacts severely to Rx power on. It's the left flap servo. When the Rx is powered on, it deploys at least 25 degrees then back to the commanded position but it does it really really fast. The left flap servo and right flap servo are plugged into one of those servo-reversing harnesses. I was going to blame the servo-reversing harness but now I don't know after hearing that you guyz are experiencing similar issues.

With Tx/Rx powered on, I don't see any glitching at all so hopefully it's only a power-on issue. Would hate to have the left flap glitch in the sky. What can I do to fix this?

Good thread! Thanks!! I've been waiting for this information for a long while.


_____________________________

"Gentlemen please! There''''s to be no fighting in the war room!" - from Dr. Strangelove

Hide Signatures

(in reply to 7kings)
       Post #: 20

RE: Servos jumping on startup - 8/13/2012 6:50 PM   
SeamusG



Posts: 3919
Score: 199
Joined: 6/16/2007
Last Login: 4/10/2013
From: Arvada, CO, USA
Status: offline 		Oh, forgot to add that it's good practice to re-bind after we have done significant reprogramming. Mixes are an area that should be followed up with a re-bind.


Hide Signatures

(in reply to oliveDrab)
       Post #: 21

RE: Servos jumping on startup - 8/13/2012 7:03 PM   
BarracudaHockey



Posts: 18350
Score: 280
Joined: 7/13/2003
Last Login: 5/17/2013
From: Jacksonville, FL, USA
Status: offline
quote:

ORIGINAL: oliveDrab

I have a Bearcat with 7 Hitec servos. I always turn on Tx first, then Rx - always. Out of those 7 servo's only one reacts severely to Rx power on. It's the left flap servo. When the Rx is powered on, it deploys at least 25 degrees then back to the commanded position but it does it really really fast. The left flap servo and right flap servo are plugged into one of those servo-reversing harnesses. I was going to blame the servo-reversing harness but now I don't know after hearing that you guyz are experiencing similar issues.

With Tx/Rx powered on, I don't see any glitching at all so hopefully it's only a power-on issue. Would hate to have the left flap glitch in the sky. What can I do to fix this?

Good thread! Thanks!! I've been waiting for this information for a long while.


Horizon/JR/Spektrum specifically warn against using a reversing Y harness (or amplifed servo extensions) in their 2.4 installations.
http://www.spektrumrc.com/experience/installationbestpractices.aspx

As for quick connect, there's a simple test.
Turn the transmitter on. Turn the reciever on. Observe solid lights on the reciever.

Turn the reciever off and then back on, one of three things will happen.
1. It will take 3 seconds to connect and the lights will be solid. Oldest firmware - should be upgraded.
2. It will connect instantly and the lights will be on solid. Flyable but you dont get a brownout/power loss indication
3. It will connect instantly and you get flashing lights. Latest firmware.

_____________________________

Andy - Helicopter Forum Moderator
AMA 77227 Leader Member- Contest Director
www.JaxRC.com

Hide Signatures

(in reply to oliveDrab)
       Post #: 22

RE: Servos jumping on startup - 8/13/2012 7:10 PM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline
quote:

ORIGINAL: oliveDrab


With Tx/Rx powered on, I don't see any glitching at all so hopefully it's only a power-on issue. Would hate to have the left flap glitch in the sky. What can I do to fix this?



It sounds like you're experiencing a similar behavior. I can say that I've never experienced any strange issues once the Rx begins responding to commands from the Tx. Once they begin talking to each other, the connection and commands have always seemed rock-solid.



Hide Signatures

(in reply to oliveDrab)
       Post #: 23

RE: Servos jumping on startup - 8/13/2012 7:37 PM   
Gray Beard


 

Posts: 12542
Score: 314
Joined: 4/21/2003
Last Login: 5/18/2013
From: Hemderson, NV, USA
Status: offline
quote:

ORIGINAL: SeamusG

Just got off the phone with Horizon support (aka Spektrum among others). They said that this behaviour in not uncommon with ''bindable'' Rx. In the cases that they have been presented with the problem, re-binding the Tx / Rx solved this deflection problem 97% of the time. The other 3% were Rx problems. Also, there is an upgrade to the AR7000 having to do with the time it takes for the Rx / Tx to reconnect following a lost signal. Original one's took maybe 4-5 seconds to reconnect. Upgraded models take something over a second.

HTH


I know several people that have sent in there equipment when Horizon was offering the free upgrades to the older gear. Everything got faster, not just the brown out problem. One LHS was selling the old RXs? He must have bought a ton of them to keep on hand? Anyway, they would still have the long lock out. H-9 told me to turn on the TX then the RX then shut off your TX and turn it back on count how look it took to bind again to see if there was an old type of RX in the plane. Doing this at the field we discovered a number of the old RXs, Horizon replaced them all free of charge.

_____________________________

Drinking and driving are illegal, why do bars have parking lots
Daisy Air Guns, keeping kids off your lawn for 100 year

Hide Signatures

(in reply to SeamusG)
       Post #: 24

RE: Servos jumping on startup - 8/13/2012 9:26 PM   
7kings


 

Posts: 112
Score: 100
Joined: 4/17/2011
Last Login: 5/19/2013
From: North Port, FL, USA
Status: offline 		I just sent an email to HH about it - hoping they'll have some information or a suggestion. Hell, if I could even get the duration of the event to be small enough that the servo didn't have time for a full swing, that would be *something*.


Hide Signatures

(in reply to Gray Beard)
       Post #: 25

Page:   [1] 2   next >   >>  
All Forums >> RC Airplanes >> Questions and Answers >> Servos jumping on startup
Page: [1] 2   next >   >>  




Jump to:


 
Google 



Search | Marketplace | Event Calendar | Local Clubs | Magazine | Product Ratings | New Products | Discussion Forums

Photo Gallery | Instructor Search | Field|Track|Marina Search

Advertisers | Hobby Vendor Resources | Rate Manufacturers | Sign In/Sign Up

SITE MAP!   : :   FORUM RULES

RC Universe is a service of Internet Brands, Inc. Copyright © 2001-2013.

Charities we support that also need your help
Yorkie Rescue | Humane Society | ASPCA | Crohn's-Colitis America


0.734RCU1