servos jumping
 

Ok here we go again. I had the jitter problem 0n another plane not long ago. Turned out to either be metal to metal on the throttle or antenna inside fuse. Anyway I have another one jumping. Engine not running turn tx and rx on and they start jumping around badly. (4) JR 125mg on ailerons and elevator (1) JR126mg on rudder (1) Hitec 425 on throttle, battery 2700mah 6V , mpi switch. I checked everything for metal to metal and nothing, antenna outside of fuse. I have tried (2) switches (2) rx's, Ner 549-X, RS600 (2) batteries both 2700mah 6V. Any suggestions

RE: servos jumping
 

Try a 4.8 volt pack that is fully charged, then step away from the aircraft with the transmitter in your hands... in other words, take the transmitter away from the aircraft or the receiver and see if they still jitter around with the lower voltage pack.

CGr.

RE: servos jumping
 

Just put a 4.8 on quick gharge to top it off and I'll give it a try.

RE: servos jumping
 

Check your Y harness and all connections.
Good luck,
Darrolair

RE: servos jumping
 

I checked that, I went threw each one trying to see if it was a bad servo or a bad ext.,or lose. I hope CG's suggestion works.

RE: servos jumping
 

It's not the battery. Oh how I wish it was. I tried a 700mah 4.8V, but servos still jumping around.

RE: servos jumping
 

Have your tried using a different receiver? It could be a problem with the transmitter as well. Since you are the same problem in different planes I think it's time to get the radio checked out. Honestly, I would send it in and have it serviced. With the glitches you are getting I wouldn't trust the radio with a plane in the air.

Ken

RE: servos jumping
 

Sounds like a good idea. I'm flying 3 different planes on this radio right now. I did try 2 different receivers, but I think I'll send it in for a check up. I'm going to try another radio, just see if it will help. The other plane was metal to metal and as soon as I changed it, everything has been fine.

RE: servos jumping
 

I had a servo jitter problem once. When I inspected my on board batery pack it had a cracked solder joint. I re-soldered it and the problem went away. Now I would rather just buy a new battery pack, but as Archie Bunker said, 'Those were the days."

(Did I spell solder properly? [sm=72_72.gif])

RE: servos jumping
 

If your on 72mhz do the servos jump around even with the Tx antenna extended?

RE: servos jumping
 

Ok here's what I tried since Ken's suggestion. I changed radio and receiver out and still same problem.

gsoav8r
Yes on the 72 mhz, and it does it with attena down and fully extended. I just tried another radio and same thing. I'm going to replace extentions one at a time and see where I get.

RE: servos jumping
 

Try a different TX. Change RX crystal to match if necessary. Trying to eliminate TX as source of problem. Also could bypass A/C switch and plug battery direct to RX for testing.

RE: servos jumping
 

Since your running a mix of servo brands...is it possible that one of the servo connections is reversed?
Not sure how that effects the rest of the gear.

Cheers.

RE: servos jumping
 

bruce88123
I tried that, switched it over to futaba and got same thing,servos still jumping around.

gsoav8r
Everything plugged in correctly, everything going in right direction. I just changed both 24" extentions from rudder and elevator, and still getting the jumps. I'm going to step back and wait for some more suggestions because I'm getting frustrated with it right now.

RE: servos jumping
 

Is the other Tx/Rx that you tried on the same channel as your original setup? If so, try a Tx/Rx on a different channel to eliminate that one particular channel that may be getting interference from something in your area.

RE: servos jumping
 

Is this happening at your home? You may be getting some type of broad frequency interference in your neighborhood. Take it out to the flying field and try it out there. Also try some different routing on you antennae.

RE: servos jumping
 

r2champion
Tx/Rx are 2 different brands, Futaba Skyport 6, channel 50, and JR 8103,channel 33.

brett65
Yes it's happening at home. All my other planes work properly with no jittering or jumping here at home. I have another plane which would jump around while running, but it did it here at home and at the field, after asking here, I found I had a z bend on the throttle (metal to metal). I did 2 things then, I changed the throttle connection, and removed the antenna from inside fuse, and it fixed it. I haven't had any other trouble from that plane since. I have some Hitec 5485's for another project and I may switch these out, and see what happens. Everything is new for this plane so really got me @^%$^#@$^[:@]. I hope crying isn't next.:(

RE: servos jumping
 

Crying is better than stomping on the plane.:D I've seen it happen on youtube.

RE: servos jumping
 

Ok, you really should try and figure out what is going on here. First thing to do is pull all the radio gear out of the plane and set it up on the bench to see if it still does the same thing outside of the plane. If it doesn't then you know there is something about your installation in the plane that is causing. If it still does it then the issue is with the radio.

Ken

RE: servos jumping
 

Im just going to throw this out there incase it helps any. You may have done this already though.

Unplugg all from the rx....then plug just a fresh battery in it and one servo...see if it happens...unlpug that servo and try another...one at a atime and see what the results are. MAYBE? [:o]

Ilikebiplanes, Yup you spelled solder right! :D

RE: servos jumping
 

Do you have your antenna fully extended?

You could be swamping the electronics on the plane with a high signal strength.

I've seen this happen on a few planes.

Once I put the antenna down, and moved away from the plane the movement stopped.

Also if you are using digital servos, they tend to continually seek the center position, which may be causing what you are seeing.

RE: servos jumping
 

Another thing to check...are you working under or around flourescent lights? In my shop I have overhead multi-tube flourescent lights and I have one plane that the servos chatter when those lights are turned on. Turn the lights off and the chatter goes away. It is the only receiver (all on 72 mghz) that does this. If I remove the plane from the shop, the servos will not chatter. I think it is the ballast in the flourescent lights that is putting out interference.

RE: servos jumping
 

Newbie here...but...I'd try twisting all of the servo connection wires, too. One lead might be feeding back into the other ones. Can't hurt. RG

RE: servos jumping
 

I'm going to do what Ken said. I'm going to remove everything and test it outside of plane. No digitals in plane, I've got a few planes with digitals and I'm used to the buzz sound digi's make sometimes. I am under flouresent lights, which sound similar to yours. I'll give it a try and move it outside. Heck I'm getting like Mickey, I'll try anything at this point.:eek: I even apoligized to the plane for calling her names

brett65
No stomping youtube videos here, crying is another story, cause if the wife finds out how much I have invested in this thing, I'm sure she gonna hurt me. On a lighter note how's the newest member of the family doing? You Getting any sleep:D

RE: servos jumping
 

I get this on a home built plane. The rudder/tail dragger arrangement is somewhat like a chopper motorcycle front wheel. It like to flop to one side or the other when it's stationary. When it flops, it loads up the servo and it'll jitter. When I elevate the rear of the plane, the juttering stops. Is it possible one of your servos are being loaded up?

Jack

RE: servos jumping
 

Goto 2.4ghz. i did an love it, no more pin boards, getting shot down. No more taxing out and getting the attena caught in the fence. :eek: The best part is if you turn the RX on and leave the TX off the servos set to failsafe not jump around :)

RE: servos jumping
 

Any carbon fiber in the plane? You dont have one of those fancy models thats built up carbon-laminate-ply do you?
Cheers.

RE: servos jumping
 

I don't think anything is in a bind. No 2.4 yet, but Joe Nall around the corner and it's starting to look better and better. No carbon fiber. I stopped messing with it around lunch, got alittle frustrated, so I took step back. I'm going to mess with it tonight, and try a few of the other suggestions I've gotten.

RE: servos jumping
 

Houston I think we have found the problem the 2 JR 125's on elevator do not like being close together. I moved it outside of shop first to see if it was the my lights making them jump. They still jumped. I took Ken's advice and pulled everything out of plane, set it up on table and started one by one trying each servo. They all seemed fine till you get 2 of them close to each other, and they start dancing. Move them away from each other they work fine. I'm very scared of them now so going to change all the 125's out with some HS-5485's. Send 125's back to JR. They seem ok on the ailerons but I don't trust them now. Atleast she isn't jumping around like a possessed plane. Now I'm not getting all happy yet cause, I haven't run her up yet,but atleast jumping is gone.

RE: servos jumping
 

Make double sure you resolved problem. I had a similar situation last week and thought it was fixed. Went two circuits around the lake and lost all response or it seemed like everything reversed. Unfortunately I was coming in for a landing and not high enough for a recovery. Totaled the plane.

RE: servos jumping
 

Pretty interesting read on chokes and twisting cables here...
http://www.rcgroups.com/forums/showthread.php?t=416226

regards, Rich

RE: servos jumping
 

Using chokes or twisting cables doesn't really come into play here on the size of planes we are talking about in the Beginner's forum. Chokes and twisting your wires comes into play when you start having long wire runs (usually over 2'-3' long) where the wire can pick up interence.

Ken

RE: servos jumping
 

While you may well be correct, and you have tons more experience than I do......it costs nothing to twist some wires and observe if it helps. Who would reasonably believe that one particular brand of servos would show these symptoms, while others do not...all in the same small plane? regards (and I enjoyed reading your website! ) Rich

RE: servos jumping
 

Not if they're Tower Pro MG995's. They can squeek and jitter at the drop of a hat.

RE: servos jumping
 

He did say earlier that he was using 24 inch extensions. These, plus the original leads on the servos, can be detrimental.

RE: servos jumping
 

I work as a designer of switch-mode power supplies. So fast rising current pulses and what-to-do about them are my bread and butter.
My boss used to say "Have Frequency, will travel" as a nod to a 50's cowboy TV series, but he's right. Steep edges have harmonic frequencies marching off into Poland.
Digital servos are characterised by having faster responses. This is achieved by using microprocessor controlled feedback along with very low resistance MOSFET drivers. The instantaneous current delivery can be an order of magnitude higher with a digital metal gear servo on 6V than with an analogue plastic gear servo on 4.8V. The significance of the metal gears is the increased moment of inertia and the much higher torque required to follow the "improved" position demand.
My suspicions would be that the pulse from the supply line to the servo is generating a signal in the signal wire, probably from magnetic cross-coupling. If that's the case, twisting may make things worse and ferrite will not help. In order to test my theory, you could separate the signal lead from the other 2 wires in the threesome. You may only need to move it a couple of mm. Of course if it works, you'll have spoiled the servo wire and if it doesn't work....well, you'll have spoiled the servo wire.

RE: servos jumping
 

Lol!

Humorous analogy!

RE: servos jumping
 

Ok we have a happy plane and happy electronics. I would like to know why the JR 125's jump around, but I'm not cutting anything up to try and figure it out. Here's what I ended up with (4) HS-5485 ailerons and elevator (1) JR 126 rudder (1) HS-425BB throttle. Thank all of you for your help

RE: servos jumping
 

If you're happy-we're happy for you. Now go fly it.:)

RE: servos jumping
 

Well done..this hobby is part skill; part electronics; part mechanics; part assembling; part sleuthing......and a whole lot of fun....

regards, Rich