Seiko Servo at 12V - Inconsitent end point

[BDSBob]

Fellow Giants with Seiko servos:

I am setting up my pull-pull, Seiko servo, 3-cell li-ion battery. When I actuate the servo quickly to the full clockwise end point, the servo arm bounces past that end point about 1/4 inch then returns to the end point. It happens verry quickly. Centering and counterclockwise rotation if fine. It does this if the ATV is 100% or 60%.

If I use a 5 cell NimH, the servo doesn't have this problem. The servo speed is significantly lower with the 5-cell.


I suspect the servo has a problem. Has anyone else observed this type of servo behavior? Am I better off using a 2 cell li-ion and go for the reliability with less torque? I am ready to dump this servo/battery and go a different route.

Thanks

[Kiwi]

BDSBOB,

I run them in my PITTS and my 3.1. Once you get it flying the airloads will stop that from happening. The servo is so dang fast with no load on it that there is not enough stopping power when it hits the end point.

I am no IMAC pilot nor 3D guru but I have let C Hyde and a few other top pilots go with these two and the rudder is not an issue once it is loaded up.

Flyit and you will see what I mean.

Kiwi

[BDSBob]

Thanks Kiwi. I guess it is kind of like when big digital servos get the jitters when you have a freshly charged NimH 5 cell pack. The jitters go away once the servo is loaded.

I agree that this servo is wicked fast on a 3 cell li-ion. - Almost scary!! I will give it a try.

[Kiwi]

You wont regret it, it is an awesome beast and you better beleive there is lack of rudder authority with it. Just dont get your fingers in the way. That thing can cut fingers OFF without any problems at all.

Kiwi

[BDSBob]

I have hear from folks on other boards that have the same symptoms and from those that don't. I really don't know what to make of this!

[BDSBob]

Does anyone know where I can get parts (amplifier/pot assembly) here in the US?

[DarcyWingo]

Basically what I said on the other boards...its a good servo but the precision just is not there, its managable though...

Send it back for a New one...

[BDSBob]

I spoke with a tech out in California that sells/services the servo. He stated basically what Kiwi was saying.
I will finish the installation and fly it.

Thanks everyone.

[adrian]

have run the seiko in my 46% ulti for one year - only servo for rudders from now on - fact

[snap a saurus]

Have this servo on my rudder in my 3.3M Yak, 3 cell Lithium for power, plenty of torque, no precision as many have said but it does the job and I will use it again, simple installation and cost effective.

[BDSBob]

Well, I decided to run the servo on the bench with my JR Matchmaker at different speeds to check the servo out. After about 2 minutes, running at a moderate to slow speed the servo began to exhibit erratic behavior. I this point I am sure that the servo needs a new potentiometer.

I called around and found that the only place that had a potentiomter in stock was tokyo-hobbies in Japan. The pot was only available as a unit combined with the servo amplifier. The cost was around $63 US. I never was able to get a total from them including shipping so I didn't order one.

Hmm - I took a look around my shop and dissected a Futaba 3004 servo and removed the potentiometer. To my pleasant surprise, it was an EXACT match! Can you belive this?

It took about 15 minutes to solder in the new pot. The servo now operates very smoothly but still overshoots the end point with no load.

I am confident that this servo will perform nicely once it is in the air, under load.

Thanks everyone!