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servo gremlins

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Old 06-18-2007, 09:12 PM
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nomaddiver
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Default servo gremlins

Hi there... I've been having some problems with my plane. I've got hi-tec servos and a 400 brushed motor. Suddenly whenever I turn the motor on, my servos get a mind of their own. I've made sure that the servo wires don't travel alongside any power wires. In fact, the only time they get close is when they clip into the receiver. I've also walked about 40' from controller and still had the problem. It worked fine until I replaced the pinion on the motor shaft, but can't see how that would pose an issue. Anyway, any help is much appreciated! Thanks in advance.
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Old 06-18-2007, 09:46 PM
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Default RE: servo gremlins

Make sure thier pluged in right-side up , your bub, scoooper
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Old 06-18-2007, 10:46 PM
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Default RE: servo gremlins

thanks, scoooper. unfortunately, everything is right-side-up. maybe it just needs a good nose dive to straighten things out! thanks again!
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Old 06-18-2007, 11:23 PM
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Default RE: servo gremlins

hrm... if the difference is installing the pinion... does it only do it when the motor is running, or does it do it all of the time?

If it only does it when the motor is running, likely something in the motor or drive system (if you have one) needs lubed up, or your pinion could be slipping.

Also check your antenna and see how it is routed. You could try laying it to the side of the plane just straight out and see if it still has the same troubles.
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Old 06-19-2007, 12:44 PM
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Default RE: servo gremlins

And since you have tweaked at the motor, make sure none of the supression capacitors have loosened.
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Old 06-19-2007, 09:47 PM
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Default RE: servo gremlins

ok, let's see.... pinion isn't slipping, antenna has no effect. i'm a bit lost on the suppression capacitors, but if those are the deals that come off of each terminal, turn into something that looks like a small aspirin, and then join together in a solder on the motor housing, those look fine as well. at least to the eye.
the glitches compound when i hold the motor in my fingers, but settle down when the controller is turned on. i think i might try a new motor and see what happens. thanks for all of the help!
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Old 06-19-2007, 11:30 PM
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Default RE: servo gremlins


ORIGINAL: nomaddiver
the glitches compound when i hold the motor in my fingers, but settle down when the controller is turned on.
Are you saying that the problem goes away completely when you turn on the transmitter (controller)?

- Jeff
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Old 06-20-2007, 02:56 AM
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Default RE: servo gremlins


ORIGINAL: nomaddiver

ok, let's see.... pinion isn't slipping, antenna has no effect. i'm a bit lost on the suppression capacitors, but if those are the deals that come off of each terminal, turn into something that looks like a small aspirin, and then join together in a solder on the motor housing, those look fine as well. at least to the eye.
the glitches compound when i hold the motor in my fingers, but settle down when the controller is turned on. i think i might try a new motor and see what happens. thanks for all of the help!

hehe yeah, I caught the same thing as jdetray. If this is happening before you turn your Tx on, then THAT is the problem =) If not I guess keep looking.

To test the caps get an ohm meter and put one lead on one pole and one lead on the other pole. It should start out in the mega ohms reading and then very shortly go to infinity if the cap is hooked up and working properly. Test that for all 3 caps.
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Old 06-20-2007, 06:32 AM
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Default RE: servo gremlins

no, turning the transmitter on doesnt remedy the problem completely, but it does slow the gremlins down a bit. with it off, the servos are pretty wild. at times even raising the elevator all of the way up and holding it there while my flaps flutter back and forth. with the transmitter on, it changes to minor jumping.
mrasmm, when you say check the poles, what exactly am i looking for?
the search continues.....
thanks guys!
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Old 06-20-2007, 06:51 AM
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Default RE: servo gremlins

you take an ohm meter and put it acrost the poles. It should give you a high resistance reading, and as you keep the probes on the poles it should get more and more resistance until it goes to infinity because of the way caps work.

But you're talking about jumping when the Tx is on and the motor is off right? That's probably not gona be the problem.

here's what I would do. Disconnect everything except the receiver battery or BEC, and then start adding things one at a time and see if you can isolate the problem that way.
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Old 06-20-2007, 09:04 AM
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Default RE: servo gremlins

mrasmm has the right idea. I would disconnect the motor and everything except for one servo. Plug in one servo at a time to see if one of the servos might be causing the problem.

The transmitter should be ON for all tests.

- Jeff
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Old 06-20-2007, 06:49 PM
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nomaddiver
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Default RE: servo gremlins

i think i've led you astray. everything works perfectly until the motor is turned on. thats when the problems start. ill try the ohm meter and see what happens!
and please disregard the links popping up in my posts... not sure why they're there.
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