Testing Servos

[scallybert]

If you have a servo that appears to work, but may well be damaged, is there a way of checking if it has been damaged ?

Story is at http://www.rcheliaddict.co.uk/main-d...g-failure.html .

Basically, an S9257 was subjected to a badly binding tail for (maybe) 20 minutes.

Having fixed the binding, a short test flight seems fundamentaly ok.

However, I'm wondering if there's hidden damage (eg damaged motor windings) that are going to bite me later, and if there's some way of testing.

[Andy from Sandy]

Secure the servo so it cannot move. Put a big disc on it. Have it connected and powered up to rx. Hold the the disc to exert a load now move the servo slowly full travel either way. You should be able to put quite a load on it before it stalls. If there is a dead spot for what ever reason this should find it.

Make sure your end points in the tx drive the servo to its full extent.

[Helimadlarry]

There are conventional servo testers which you can purchace to test your servos, such as the Hitec HFP20 servo tester and programmer. However it is quite expensive at £80. A more cost effective way would be to just set the servo up on a model or on the bench and test the servo with a moderate load. Listen out for any "out of ordinary" buzzing or ticking when it moves. You could also try watching the servo horn as you move the transmitter stick very very slowly. Look out for and jumps or speed increases/decrease whilst maintaing a constant speed with the stick. Also If you feel confident enough, remove the top case and visually inspect the gears for any missing teeth.

Hope this helps.

Lawrence

[scallybert]

Thanks.

I doubt the gears will be damaged. Unlike in a crash, the gears (probably) won't have been subjected to anything more than the motor's stall torque. Which you'd expect them to be designed to take.

I reckon it's only likely to be the motor, or maybe the servo motor's ESC, that might have been damaged.

So checking the torque (as suggested) seems like a good idea.