Right Rear Servo 'Twitches'

[Adam Stephens]

Hey Guys,

So I've figured out why my Blade CP has been 'twitchy' lately and with increased power will sometimes just 'shoot' up into the sky. My right, rear servo seems to spasm ever so slightly with increasing varience as I increase power.

There are 4 things that I can think of that might cause this. Could anyone with more experience offer some advice?

1. The servo wire to the 4 in 1 unit is too close to the main motor which is causing interference, as the motor gets more power the noise increases, therefore causing the twitch.

2. The servo is sarting to bug out on me and needs replacement.

3. The 4 in 1 unit is bugging out on me and needs to be replaced.

4. The transmitter is not giving a consistent signal to the receiver.

I'm thinking that 1 or 2 are the most likely possibilities, but how do I check? The electronics are the peices I know the least about. Any help?

[Psikelly]

Try reseating your crystals. Pull em out and clean the connections a bit and make sure theyre seated nicely. You could try move the servo arm by hand. Move it slowly and smoothly and try feel for any clicking or resistance.If you feel anything clicking, grinding or binding then just change it.

Another way to check it is to unhook the motors, flip it into idle up mode and increase the throttle. Watch for twitching etc. If you see any twitching then try plug that servo into another port and plug 1 of the 2 remaining servos into the trouble port. If the problem follows the same servo with problems then you know its the servo. If the other servo starts twitching then chances are its a 4 in 1 prob. Just a couple things to try.

[Adam Stephens]

Great suggestion! I'll look into that! Hopefully it's nothing serious, if not do you want to fly this weekend?

[JeffElecRC]

Adam, I've usually found servo twitching is an often electric magnetic intereference (EMI). Sometimes the antenna is picking up noise and all the servoes do a little twitch. But since you've only got one servo twitching you are probably right that the servo wire to the 4in1 is too close to the motor. You should also consider that as the motor gets older the brushes wear out and they generate more sparks and more EMI.

To check this you'll need to move that servo wire. As I recall there arent too many options though, is there? Do your best. Put the servo wires on one side and the motor wires on the other.

Also, move the servo arm by hand (if possible) and listen for any broken gears. Or disconnect the servo from the swash and wiggle the Tx stick while you listen for soudns of a broken gear. If you've got a broken gear, you can get a space gear set and replace the gears.

[Warren]

I get the same thing, besides keeping the wires as far from the motor as possible, I got a toothpick, and put some white grease around the servo arm just where it goes into the server - tried to see if it was a "stutter" type of problem - didn't seem to hurt -

I can idle up sometimes, and just watch the servo(s) jitter before I actually take off, then they seem to settle down -

( when I used to race electric cars, this was a problem when the transmitter was too close to the car )

be interested in all of the findings..........

[Warren]

I was talking to someone about this today who is into electronics, short wave, and other goodies - he mentioned that such a small amount on interference - if that is the cause - should be able to be defused with aluminum foil wrapped around the wires - who knows -

I tried it this afternoon, in between the rain, and had no twitching - or mid air dropping - which I got last night -

I have noticed that if I do get any twitching it seems to occur close to the end of the battery charge ??

anyhow.......................

[Warren]

Just looked at the latest issue, they review the CP Pro, and in the article mention a similar glitch - but they just mention it, and don't follow it up - seems like a small factory defect of some kind.........

( being as most of it is based on the original CP design, I guess it just travelled along to the Pro... )

it would have to be, to be so wide spread - a design issue maybe ??

In case you've never looked - the mag URL is

http://rchelimag.com/

so far it has had many useful articles :)