Resistor troubles

[Ockham4230]

I have a resistor on my 400 speed motor that is giving me a great deal of trouble. It breaks due to motor vibration. I solder back on and it will break again with only about 45 minutes of flight time. It is on a e-powered sailplane so that 45 minutes is only about 25-30 minutes of powered flight.

Any suggestions welcomed. Let me know if you need more of the particulars.

David

[gravydrive]

The next time it breaks, remove the excess solder and use some sandpaper or a jeweler's file to "rough up" the area to which you will re-solder. The solder should have more holding power on the rough surface.

[slipstick]

There shouldn't be any resistors on a Speed 400 motor.

It might be a capacitor, in which case make sure the leads are as short as possible. A physically smaller/lighter component of the same value might work better. If you get really desparate there's nothing stopping you from sticking the component to the motor case using something like Goop (that'll soak up some vibration ;)).

Steve

[Rodney]

Like slipstick said, there is (or should not be) any resistor. It is most probably a capacitor. Try a 0.1microfarad disk ceramic (available from Radio Shack or any electronic parts store instead. As said, keep leads as short as possible.

[Ockham4230]

My bad. It is a capacitor not a resistor.

Re: Gravydrive - it is the leads that break not the solder or the solder joint.

I will shorten the leads. Is there a too short that I need to avoid here? I had been hesitant to shorten the leads because once they reach their shortest, if/when it breaks again I have no recourse but to replace the Capacitor (got it right this time ;) ). The instructions call for insulation between the power lead and the capacitor (none between the capacitor and the ground on the side of the motor). Should I shorten the leads evenly? If not which side should I leave long?

Thanks for the help.

David

[Dan Baldwin]

Short leads on the capacitor will not hurt a thing as long as they are still long enough to reach. I fly all brushless now, but I flew brushed for years, and I never had a noise suppression capacitor lead break. If you are getting enough vibration to break the lead on that capacitor, I suspect that you need to balance your prop and or prop adapter.

Dan

[slipstick]

I really did mean as short as possible ;). Don't stretch or strain the wires but do wind them round the terminals so they're not held on purely by the solder. I must have fitted a couple of hundred suppression caps like that and I've never yet had one break.

It would be worth posting a close-up photo of exactly what you're doing because there's something strange going on.

Steve

[Ockham4230]

I will try to get a photo done but I'm behind on a work project (and avoiding getting caught up even now) so it may be a few days before I can post a photo.

Regarding balancing the prop (no adapter). It is a folding prop. Is there a good way to balance it? I tried to make each blade have equal weight. I figured as close as the prop mount was to the center, being out of balance there would not matter, but obviously something is amiss.

On the wiring I run each capacitor from a power post to the side of the motor. I did use just one solder on the side of the motor so both ground ends go to the same point and that had them pretty long. I did not trim the leads down at all. I can trim them down even shorter if I don't use a common solder point on the side of the motor case. Should I do that or keep them long enough to have a single ground spot on the side of the case?

They keep breaking on the power end just off the post. Could I be heating the lead up too much when I solder and thus making it brittle? I definitely have had more trouble and hence used more heat on the post soldering then on case (ground) solder.

I have had speed 500 and 600 motors in a larger plane which never had a broken capacitor, but this is the second motor in this plane with the same results. (Well not exactly - the first motor the output shaft was a bit short making the prop mount tenuous. I figured that caused vibrations resulting in the capacitor breaking. I changed the motor for a more powerful graupner with a longer out put shaft. It really improved performance, but I have continued to have the capacitor problem.)

Hope this helps explain a bit

[vintage1]

make the leads as short as possible
take them direct to the case
Fit one across the brushes as well (sleeve the wires on this one)
Use a blob of silicone, hot glue, or epoxy to the can to stop them flapping like a big girls blouse.