Align DS425 strange behaviour

[Si Goodchild]

Guys,

I just noticed that the DS425 servo on the back of my 250 has a strange behaviour when I apply full rudder one way. There's no problem when I move the heli to get the gyro to move the tail, but when I manually command rull rudder one way the servo travels about 75% of the way, then pulls back a little before proceeding to 100% deflection. This only happens one way and is repeatable, i.e. it happens in the same place every time no matter how slowly I move the rudder stick unless I push past this point really quickly. The servo is connected to a 3Gx and this doesn't happen on my other other heli with the same controller.

I'm thinking junk the servo, but would like your thought before I do so.

cheers,

Si G

[Si Goodchild]

Correction - it happens right at the limit of travel (say 90% deflection) and in both directions of travel. Now I'm thinking "re-setup the 3Gx". Sound sensible?

[Si Goodchild]

Gentle bump - I'd appreciate your ideas before she slies again.

Si G

[coolice]

Hey Buddy.

It's a symptom of the 3GX, I have seen it. Indeed if you hold the rudder stick at the right point you can have the tail servo jitter/tremble almost.

It's not a problem in flight from what I've seen, so don't worry about it. I think it might depend on the tail travel limits programmed into the 3GX as to if you see it or not, but I'm not 100% sure.
.

[scallybert]

TBH, both your description and Coolice's sound more to me like the servo having a dodgy point on the potentiometer track.

I think I'd try plugging in another servo to see if I could replicate the behaviour with that.

[cjcj1949]

If you want to be sure test the servo with known inputs. It sounds ok to me. Difficult to predict what sort of output is expected from the controller.