Ernie Misner

Greetings, I have a Futaba standard 3004 servo on the rudder, and recently it has started twitching like crazy, but only when the stick is around the centered position. I've eliminated everything else now so it has to be that servo.

Is this a common way for a servo to go bad???

Thanks,

Ernie

freeair

disconnect the pushrod end from the rudder servo and see if the servo still twitches. there could be abit of strain on the servo in stat mode, also you can try the transmitter trim [ rudder ] a click or 2. normally these are quite good servos , other than it may have a dirty POT that you can clean.

A.T.

Quite common in a boat or yacht, especially one used in salt or brackish water and certainly in those in which the rudder post has rarely been removed and regreased.
1. Salt and corrosion build up causing the post to stick and either jam or overload the servo.
2. Servo is not water tight, any leaks around the hatch? Keel etc?
3. Water can run down fingers into receiver or down servo leads, have you tried another servo in same slot to check if same thing happens with another servo?
In need, refer to sub section "Glitches & Jitter in RX & Servo - causes and cures" at
Alan's Hobby, Model & RC FAQ Web Links
Regards
Alan T.

slarty

There is a possibility that the feedback pot has worn out around the centre position. Some pots can be opened up and inspected, cleaned as a temporary measure, put back together and used again. Always best to have the pot replaced.

onewasp

Nine chances out of ten slarty has it identified.

BTW regarding your quote which I have printed above _____ The answer is NO. But it is a VERY common way for servos to show wear.

"Bad" to me, implies fault, while "wear' implies what has actually occurred.
Depending on application and use this can be found in servos after 50 flights, sometimes less. (minor but enough to screw up a precision sequence).

This is such a universal occurrence that it fostered the need for 'soft mounts' and is one of the benefits of electric powered flight which does away with the "vibes" inherent in reciprocating engines.

BuschBarber

My Feedback: (2)

Have you tried other servos on that same channel. Sometimes the pot on the Tx can be at fault. Just a thought. It is more than likely the servo, though.

Ernie Misner

Hi guys, thanks for the great info. Yes, I've tried other servos in the same channel and they are fine. Sounds like the worn pot then and not much of a loss with a standard servo.

I'm off to check out the link about glitching. sounds interesting!

Ernie