Servo Oscillation on start up

[jimbo]

Had a rather odd thing last few flights with a model and was wondering if anyone had seen it before.
On startup the left aileron would go into up down oscillation from endpoint to endpoint. Happpened twice now.
On the last time I moved the TX away and it cleared itself.
I then fully range tested it and then flew and it worked no problem, when i then moved the TX next to the model there was no such oscillation at any time. Flew the model and everything worked fine.

Is this the TX overpowering the RX or a servo issue, its a HS85.
Is the servo going into some sort of odd state, receiver is a futaba 617faast. Battery is of course fully charge.
Cheers,

[jimbo]

Never happened before though. And when I put the tx next to the plane after start up it doesn't do it. Not sure what channel it is, but prolly 1 or 2 as its ailerons.

[Trevor]

[quote="MarkDev"]Quite a common thing on my FrSky 2.4ghz set up, move the two, tx n rx, apart and they settle down with no more issues. Less than a metre apart and it happens again. I think this is common to 2.4. I expect someone will have a full explanation?

M[/quote]
If the receiver is swamped by the transmitter being close by, I call that bad receiver design. It's nothing to do with 2.4GHz operation, in fact I seem to remember seeing it rather more often in the 35MHz days.

[terry white]

Hi Trevor,

What an excellent web site. Thanks for posting. I Hope to see you on the Purbeck slopes this year.



(Robbie, is it possible to arrange so this Webb site can be reached and viewed from the home page for future viewing?) Regards Terry

[Barry_Cole]

Never happened before though. And when I put the tx next to the plane after start up it doesn't do it. Not sure what channel it is, but prolly 1 or 2 as its ailerons.

Jim,

I have heard this before, and the thought was that if Ch 1-2 were used for a bind plug, or shorting plug for setup.and it may be caused by the Rx checking to see if a bind plug is fitted.

BC

[Weds]

[quote="MarkDev"]Quite a common thing on my FrSky 2.4ghz set up, move the two, tx n rx, apart and they settle down with no more issues. Less than a metre apart and it happens again. I think this is common to 2.4. I expect someone will have a full explanation?

M[/quote]

Wish this thread had turned up sooner, just swapped out servo, extension lead and eventually Rx to cure exactly the same fault on a Frsky system. didn't think it would be due to swamping signal.

Aileron servo would go full travel either way when operated. Did it at home under test and also on the flying field before launching, always at close range. Never thought to move away and try again..

[robc]

Hi Jim,

Funnily enough I've just had a very similar problem with an HS85 in my Ventus, it appeared to be overshooting when using it through a receiver for the first time. I was going to replace it as it's not new but it seems to behave itself with a servo checker so I'm going to do some more investigation.

Rob

[jimbo]

Rob I had a chat with Stan at the weekend on the hill. He explanation was that a small piece of carbon can get stuck on the pot on the servo, forcing it not to be able to centre. After a while the carbon moves out the way.
I have my reservations as it seemed to be related to tx position next to model. Further testing required here too.let me know how yuou get on.

[jimbo]

Update - took my servo out of the model, stuck it on the servo tester - servo all over the place. New one ordered
Now are pots repairable? Gears looks good?

[RobbieB]

'.............
Now are pots repairable? Gears looks good?

Jimbo, for the cost of an HS85 - lash it.