Problems with JR DS8411 ?
 

Hey.

I know JR called the 8411 back from the pilots useing them in helis.
But is there any problems with the servos in giant scale planes, like 40% extra and so on?

No problem with mine so far...
 

I am using 8 JR ds 8411 servos on my 35% Cap. Have over 100 flights in a two year time frame. My only gripe is that they oscillate the surfaces quickly when there is no load on the surfaces.

Re: No problem with mine so far...
 

I have the same issue with oscillation. Unfortunately, the oscillation also causes premature wear when then leads to slop in the gear train. Its a never ending cycle.

I have been replacing the gears in my 8411's every 50 to 100 flights to solve the problem. I've since switched to using other servos (Airtronics 94358's, 94258's, Multiplex, etc). Just to expensive to run the 8411's. :(

Problems with JR DS8411 ?
 

what does "oscillation" means?

Problems with JR DS8411 ?
 

For US customers, we will repair/replace the gears on 8411's at no charge when you send them in to our service center.

Elevator goes up and down ...
 

One or both elevator halfs and sometimes the rudder go a few degrees up and then a few degrees down. the cycle is about 6 or 10 times per second. If I disconnect the surface from the servo, the servo is rock steady. But with the relatively large surface attached, when the receiver is powered on, it oscillates the surface. If I dampen the surface (touch it with a finger to stabilize it, the oscillation stops). But if I bump it, the oscillation starts again. I think that if there were zero play in the control system, it would be fine. But there is always some play, even with the best system. I am using rocket city links which are pretty good in this regard.

Problems with JR DS8411 ?
 

Sometimes if the servo is mounted too rigidly it will do this, be sure that the servo screws are not too tight, and that the mounting rails are not tight against the servo. If there is too much slop in the gear train it can aggrivate this, and also any slop or flex in the control system can as well. It is likely that if they will stop when you touch the surface, there is nothing wrong with the servos aside from maybe some slop, but there would be no fear of any type of failure. You can send them in and we can check them out and perform any service required to get them like new again.

Thanks, Danny
 

I will double check the mounting. I know that I used the rubber grommets. As I said, when I remove the surface the servos are all fine. I am using pretty long servo arms and relatively short control horns in order to get about 50 degrees throw. So any slop at all gets amplified so to speak. For example, the same servo on the aileron never oscillates because the aileron has less moment of inertia I believe.

Problems with JR DS8411 ?
 

i live in Denmark (europe)
Do we have any JR service here.. or can i ship them på USA?

Problems with JR DS8411 ?
 

That service is just a service that we provide in the states for servos bought in the US. You will have to contact the company that provides service in your area for more information on their policies, it looks like Graupner is the service center in your area. You can contact them at 49-7021-722-0.

Problems with JR DS8411 ?
 

thank you.

Problems with JR DS8411 ?
 

No problem!

Problems with JR DS8411 ?
 

I have the same oscillation problem with my JR 4721 servos on the rudder of my 33% Hanger 9 Cap. So I don't think the problem is related to just digital servos. My ailerons and elevators are solid as can be, just the rudder oscillates.



Mr Snyder, do I need to send in my 4721's to have this problem fixed, or is this just a worn gear problem that I can fix myself?

Problems with JR DS8411 ?
 

In your case it may be pot wear. Send to Horizon for repair.

Problems with JR DS8411 ?
 

The rudder it can show up pretty easily since it puts no load on the servo, but it may be pot wear. If you can send your servos in we can check this out.

Problems with JR DS8411 ?
 

would counter balancing the control surface help this problem?

Problems with JR DS8411 ?
 

There is a air load counter-balance on the Cap's rudder. i assume you meant a weighted counter balance. While in flight, airloads on the rudder are the same on each side and the oscillations stop. Its just an ugly problem on the ground to watch your rudder oscillating back and forth. No problem in the air.

Problems with JR DS8411 ?
 

Counterbalancing may or may not change this, on the rudder it shouldn't make a change.

JR 8411 chatter
 

I'm flying several giant scale planes on a JR 8103 system with mostly 8411's. I got used to the "buzz" of big control surfaces on the 8411's, but also had some macroscopic movement, or "chatter", which is a lot more worrisome and translates into glitches in the air. Sometimes this seemed to go away when I switched out one brand new 549 (FM) receiver for another.

I spoke recently to a Horizon JR technical consultant who seemed pretty sure that my problems are because I'm trying to run 8411's off a 549 receiver, and that I should switch to PCM (649 receivers).

I've got a total of eleven JR 549 receivers, so the switch is gonna be a bit expensive, but I'm more than willing to do it if it solves the problem. Any opinions or first-hand experience? This "chatter" occurs even with engine off, and some of these planes aren't even gassers.

mt

Problems with JR DS8411 ?
 

Earlier versions of the 549 did have problems when there were a few digital servos plugged into the receiver causing feedback to the receiver, that the receiver whould then cause the servos to jitter. We have any update for that receiver if you would like to send them in we can do.

Problems with JR DS8411 ?
 

Thanks. Will do.

Will switching out to 649's and PCM mode on my 8103 solve the problem as well?.

mt

Problems with JR DS8411 ?
 

Yes, the 649 would not have this problem. Only the 549 receiver has had this issue.