[SpadHawk]

Hi
I went flying yesterday with my spazzler. it has two servos for the ailerons.
each aileron has an extension on it and are pluged into a Y harness.

it flys nice, very fast roll rate. but I noticed on the ground if I put my transmitter antenna near the right aileron or next to the plane antenna I get flutter in the one aileron and sometimes both but not in the other servos.
Whats up with that? does anyone have any idea?
I do notice the very infrequent glitch in the air.
Please Help
SpadHawk

[JimMcIntyre]

I was ok until you mentioned "infrequent glitch in the air"...

Proximity of your Tx to your Rx can cause "swamping" of the signal leading to glitches but, glitching in the air is never a good thing.

If it's always on the the same control surface, I'd suspect the servo, swap it out and see if it solves the problem, if not try a replacement crystal. No dice, try a replavement switch (often overlooked). next try connectors etc.

If the problem persists have the Rx and Tx checked out. If they check out ok and you still have a problem, start looking for vibration problems with your isntallation or external interference (got a ham bussy with a frequency scanner)?

HTH, Jim.

[SpadHawk]

Thanks Jim I'll try your suggestions and see what I find out
SpadHawk

[SpadHawk]

Hi Jim,
I changed out the servo that was giving me the jitter and there is no more jitter. so whats wrong with the servo?
Its an airtronics 94102. I noticed one other airtronics servo that moves just a tiny bit when my antenna is put near it. I replaced with a hitec and no problem.
SpadHawk

[JimMcIntyre]

Often, the feedback potentiometer wears out or picks up some dirt making the contact less than perfect resulting in "hunting" (the servo can't find the requested location). This can cause other problems (especially if left to degrade) as it can send 'spikes' back to the reciever.

It could also have been (but less likely) the actual servo connector.

The only way to be sure if the servo was the cause is to connect it to other channels and test. If the problem follows the servo, you have your cause.

As I mentioned before, brining the Tx antenna too close to the Rx (known as 'flooding') can cause problems under the best of conditions. At that point, even servo leads become anttanae and you have a lot of undesireable signal 'echos' wreaking havoc on your system.

[Gary Maker]

Jim, I've had a couple of servos that have developed the jutters that were not all that old. A friend said he uses a good quality contact cleaner and gives a blast to the inside of the POT while working it. He told me the same thing that you just said, sometimes a bit of dirt or residue collects in the pot and the servo can't stop on this point. Spraying the cleaner seems to have worked. Is this a good fix or am I just asking for trouble later on!
Appreciate your expertise here......Thanks!

[JimMcIntyre]

Servos put up with a lot of abuse, many of the cheaper bushed ones are not suited to use in oversized control surface of typical Funfly/3D type aircraft and especially not in pull-pull setups. Be aware that often even a sport plane can be flown in a manner that puts as much strain on a servo as extreme 3D flying. Flutter is the biggest servo-eater of all and I cringe every time I hear it on a sport plane. I've had many warnings go unheaded on this particular matter, two flyers at my own club learned this lesson the hard way recently, even after I'd warned them weeks before... a word to the wise.

There are a few electronic cleaners (aka. contact cleaner) on the market but, a lot depends on the quality/design of the original pot. Some, the wiper simply wears through the carbon trace that serves as the resistance, others are superior while the best are sealed and contact cleaner will have no effect other than lubrication.

Eliminating binding in control surfaces will reduce heat to the pot (and other components). If you hear a servo buzzing, you're stressing the output shaft, consuming power, reducing safe flight time and longevity of the servo.

What I find happens most often is the centre section of the pot goes first, (typically of aileron servos on Funfly planes where there is a lot of backlash/flutter). I swap these out and put them in the questionable pile where they typically get re-used as throttle servos in a combat plane or some other use where any failure mode is acceptable (eg. candy drop or some other non-essential surface).

I used to buy a lot of the cheaper bushinged servos but found they didn't last long and servo replacement was winding up costing me more in the long run.

[SpadHawk]

I tried the airtronics servo on another receiver on a different frequency...and no problems .
????
SpadHawk

[JimMcIntyre]

It's possible the servo is emitting some radio noise on a harmonic that would interfere with your one radio. Obviously this is just speculation and would require some expense to determine. If it were me, for the price of a standard servo (and an old one at that), I would probably just donate it to some high school electronics/robotics program rather than taking any chances....

[SpadHawk]

the servo is only 8 months old
Spadhawk