Scorf

My Feedback: (10)

Hey guys/gals

I have always been a big fan of the futaba 9252 digital servos, flying mostly heli's for awhile now I started to get back into planes again. Here is the problem, I put 4 brand new 9252 servos in a 70 size profile and when I power them up they are fine but, if you touch any of the sticks on the radio it starts the elevator/rudder/ailerons etc into a non stop shudder while in the neutral position. If you add any input to them the shudder stops but continues when back in the neutral position. I have tried changing to a used set of servos along with the receiver and battery but, no difference. Does anyone have any ideas what may be causing this ? I forgot to mention, if you grab ahold of any of the control surfaces with your fingers, it stops !! You're input is very welcome !!

Thanks, Darryl

tuwood

Usually that happens on mine when I have some sort of interference between the radio & the receiver. For example if I have my charger plugged into my plane even with the power switch turned on (not charging) my servo's chatter like crazy. As soon as I unplug the charger everything is fine.
I would also check your receiver wire & make sure it's not near any servo wires or pushrod's.

Good luck

LSP972

My Feedback: (13)

I have encountered this, on an H9 ShowTime, on the aileron servos.

Conventional wisdom (from very experienced folks) says this is because the servo is about to die, from one malady or another; bad pot, etc. When I changed the servos to two brand new ones, they did the same thing. My problem was just a tad different; they would chatter while just sitting there. Moving the surface, or touching it, would stop the chatter. Hmmm...

Without going into a detailed (and rather lengthy) explanation of why, I think this has something to do with the actual geometry of the linkage. Basically, I changed from a 1:1 ratio- servo horn and control surface horn equal lengths- to very small servo horns. That's when the trouble began. Then again, I did the same exact thing on the two elevator 9252s, and they are working quite happily with no complaints.

I solved my problem by fitting two 3305s in the wings. The two suspect servos were put in a "beater", on ailerons, and are working just fine. So I am forced to conclude it was something in that particular linkage geometry that the servos didn't like. Again, that's my opinion, which could be way off base.

IOW, try changing your linkage geometry and see what happens. All it will cost you is some time. What it did for me was make me realize that, as much as I like the 9252, these 3305s (which sell for half of what the 9252 does) do an equally fine job; for ME. As I get older, I find the extra resolution and precision offered by the digitals simply isn't as important as it once was.

YMMV...

Scorf

My Feedback: (10)

Steve Campbell

I am inclined to believe you are correct in assuming the linkage geometry has something to do with the cause of said servo shudder but, here is what did to correct the problem. I noticed the control linkages were loose, not sloppy but very free with absolutley no drag at all. I took your advice and changed the geometry a little and then changed the clevis clips to ones that fit more snug, this is what seems to have stops the shudder. Soo.. I believe the combination of resonate vibration and linkage geometry were the cause of this electronic misfit. I have yet to fly this bird soooo...lets hope it does not change in flight !! LOL

Thank you !!!

Darryl

fritzthecat

My Feedback: (4)

With a 70 profile you most likely used servo wire extensions. Try it without them to see if it makes a difference.

Fritz