FixedWing172

Hoping someone can help determine the problem of multiple JR 8611 servo problems. THE PLANE-Extreme Flight Yak, DA 50, JR 8611s, Duralite 7.4 with 6.0 regulator. THE PROBLEM-Plane has been flown many many times over the last 1-1/2 years without issue. Yesterday while preflighting for third flight of day one of the elevator servos was seriously fluttering around neutral. Moving the elevator up or down would cause the problem to stop. Moments later the other elevator half began to do the same thing. This is not just a little vibration here but major jittering, enough to vibrate entire airframe. TROUBLE SHOOTING-Brought airplane home and changed receiver, transmitter, battery, and servo extensions with no effect. Removed all other servo leads from rx except for suspect servos but problem remained. Changed both elevator servos and the problem went away. Brought the airplane back to the field next morning and one aileron servo now doing same thing. Coincidence? UNLIKELY. Battery voltage has been fine throughout problem. Checked the voltage after the regulator and it was right around 6 volts which is normal. My only thought at this time is possibly an intermittent voltage problem which led to servo damage. Your thoughts and input would be very much appreciated.

The Ghost

It will be the feed back pot in the servo going bad. The vibration over time has wiped out the pots around center.

Cheers.

FixedWing172

Dear Ghost,
Thanks very much for the reply. If you are suggesting that three servos have worn out over time with all experiencing problems precisely on the same day I would have a hard time agreeing. Thanks anyway though.

Zeeb

My Feedback: (41)

While I've just recently started using the 8611a servos so I can't speak from experience, but from what I've read about them here, what Ghost has told you about them is one of the problems they have although that is not specific to JR alone. The other problem with the 8611a seems to be gear wear and then the servo has a problem centering is what I've read about them on this forum. It's one of the arguments for using the new HiTec 5955(?) with the titanium gear set...

Whether you consider it too much of a coincidence or not, I'd say if changing the servos stops the problem and the model has seen that much use, it is the servos causing the problem but that's JMHO.

Rodney

Try just unplugging and repluging in any connectors. it could be corrosion over time which is effecting all connections now. If unplugging and replugging them in helps, it confirms that as a cause. The demating and remating of the connectors burnishes off enough of the corrosion to again get good continuity.

ptmac3

My Feedback: (3)

I had a very similar problem with two aircraft in a very short amount of time. The servos would jitter erratically and seemed to hunt for the neutral position before they would stop. Touch one of the sticks and it would start all over again. It was only on the servos with extensions. I replaced all the connectors with 3-pin Deans Connectors, problem solved.

sfsjkid

Doesn't sound like the pots in this case though connections and possibly a change in weather? The only other thought is to try going to 4.8V to see if the problem remains. Haven't thought about the exact cause, something in the filtering(?), but have had the same happen, solved by going to the lower voltage.

dirtybird

My Feedback: (5)

The JR 8611A is set up with a very tight deadband. Wear of the pot wiper element and gear wear can cause this flutter. It sounds to me that your servos are needing an overhaul. A flutter on one will cause fluctions in the battery voltage that can cause the others to start hunting. You could also have a problem with the filter on your regulator. You really need to find someone with an oscilloscope that can see what is going on.

skiman762

may sound dumb but try a new rx crystal those gassers shake things up more the people think foam or not