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JR servo Jitter??

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Old 08-16-2003, 06:45 AM
  #1  
IXLR8
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Default JR servo Jitter??

I have an issue with some JR servos and I would appreciate any advice I can get because I am baffled. I recently accuired my first JR servos. Up to now I have always used Futaba, Airtronics, Hitec, FMA, ETC but never a JR. I have several different types of RXs with different servos that I run off my Airtronics RD6000. Futaba, Airtronics, FMA, Hitec etc with no problems.

I decided to use JR 531s in my UCD. Problem is they jitter in the elevator and throttle channels, yet they work fine in the aileron and rudder channels. The one thing I see is that the Throttle and Elevator channels on a JR and Airtronics are switched but this shouldn't make any difference in how the servos work should it. At least I have never seen this problem before. I tried other servos(Futaba and Airtronics) in their place and they worked like they should. I tried the JR servos with a JR TX and RX and they work fine. But with the Airtronics TX these JR servos jitter when their plugged into elevator and throttle channels.

Does anybody know of a reason why these servos would do this?

I did check the batteries as a low batery will cause jitter but it is fully charged. I even tried a different one that is also charged.
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Old 08-16-2003, 05:29 PM
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Default JR servo Jitter??

Well I tried a few more combintions including a using a Futaba RX and I still get the jitter. I also tried out a JR 517 servo in the throttle channel and it worked fine.

Anyone?
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Old 08-17-2003, 12:56 AM
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Default JR servo Jitter??

Are you using 6.0V batteries?

Do the servo in question jitter when the servo arm is removed?

Many servos typically jitter when the static voltage is high as in just off the charger.
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Old 08-17-2003, 04:37 AM
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Default Jitter

Don't know about 531's but my 537's humm and it's because they are continually searching for dead center. So says JR.
I just had a jitter issue with a JR 549 receiver which was draining my battery. Tried everything but finally switched rx's and it went away. That rx is going back to Horizon.
Is your battery getting zapped?
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Old 08-17-2003, 05:52 AM
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Default JR servo Jitter??

I am not using a 6v battery but the first pack was freshly charged at first although I spent a lot of time with the radio on and it still was doing it.

They do act like they are trying to find center but can't. I thougt at first it might be the RX or that the connectors were too long so I switched RXs and also hooked the servos dirrect to the RX but still they jitter. By the time I was done I had tried five different RXs and the only way I could get it to work was if I used a JR TX but never with the Airtronics TX. I ended up putting Airtronics servos in it. I also tried a couple different battery combinations with no luck. These things seem to be the most pickey servos I have ever seen. After going with the Airtronics servos for the elevator I still used the JR servos on the rudder and aileron and they both shook until I changed out the extentions, although in both cases if I switched the JR servos for another they worked fine. It seems very strange that these servos give me problems l when I use my Airtronics TX but work really well if I use a JR TX. I have heard many good things about JR servos and would like to try them out but I have never heard anything about them not working with Airtronics stuff.
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Old 08-17-2003, 10:13 PM
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Default JR servo Jitter??

catboatr

I just sent JR an email regarding humming servos. I have the 537's and they hum at neutral - with little or no load. I have 4 JR and 3 Airtonics in the same bird and the JR constantly hum. If you slightly move the servo it will stop (and I mean SLIGHTLY). I have had 4 Airtronics setups and they never stalled or buzzed unless there was a real load against them. This is my first JR and it has never taken flight yet.

Is this a potential battery drain hazard (running a 1200mah flight pack) or does JR advise it is normal?

Thanks
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Old 08-17-2003, 10:27 PM
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Default JR servo Jitter??

Normally when servos humm (or Jitter) it is due to some sort or drag on the servos but my case I hadn't even hooked them up to anything yet.
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Old 08-17-2003, 11:13 PM
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Default Hum is normal

tks1 - JR says it's normal and it is not a battery drainer. I've been flying several ships with 537's for more than a year now without problem.
They really worried me when I first installed them but now I don't even notice the hum anymore. You may fly with confidence!
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Old 08-17-2003, 11:50 PM
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Default JR servo Jitter??



Thanks alot. Now I can test fly my Beaver without worrying about the radio system. I didnt think it should be a problem.

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Old 08-18-2003, 12:46 PM
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Default JR servo Jitter??

Servos with a tight deadband will buz more than ones that have a wider deadband but they are more accurate, I find JR servos used with my Futaba or Hitec Rx (6V) and MPX tx do buz slightly but work very well and battery drain does not seem a problem
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Old 08-18-2003, 04:47 PM
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Default JR servo Jitter??

I had servos which hummed at first. I too was concerned. The chatter is almost non existent since getting about 20 minutes in the air. I think the gear train and pots needed to break in a bit to get accurate positioning???? The only time I notice anything, is when the radio is fired up for the first time after a week of being dormant. It goes away after sweeping the servos through their travel.

If it makes noise, just start the engine up...... eventually you cannot hear it! (just kidding)

Good luck,

BR549
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Old 08-18-2003, 08:01 PM
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Default JR servo Jitter??

Humm normal? It seems strange especially since they don't buzz, humm or jitter at all if I plug them into the aileron or rudder channel. Just on the elevator and throttle channels.
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Old 08-22-2003, 06:18 AM
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tks1
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Default JR servo Jitter??

JR replied saying that a little humm or buzzing in the servo is ok when at neutral as long as it goes away with a little pressure and as long as it isnt due to excessive resistance (ie - binding control surface etc).

Jitters on the other hand arent a good thing. I dont know why yours would only jitter on certain channels IXLR8.
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Old 08-22-2003, 02:02 PM
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Default JR servo Jitter??

They do more than just humm a bit but don't seem to really cause much if any movement on the control surface. I could probably fly with them but would worry about the batteries wearing down too soon. I like the JR servos and the ones I left on the rudder and ailerons work well and I have done some flying with them but I guess from now on I will have to stick to the other brands.
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Old 08-29-2003, 01:59 AM
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Default JR servo Jitter??

i just purchase 6 Jr 4721 hightorques. and every one of them do the funky chicken (jetter). i replaced 2 of them with DADs. wish i had more of the DADs. but when you spend $87 on a damn servo, you expected to work like a dream. and ofcourse when i contacted Jr. who do you think they blamed, my set up. im trying to sell the damn things very cheap.
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Old 08-29-2003, 02:18 AM
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Default How cheap?

If you really want to sell them cheap, please contact me.
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