I had a throtle servo failure the other day on my katana it was an 8911 and it fried the wires The way it is mounted mechanicaly is spot on nice and square short swb 4-40 push rod with ball joints at each end.I am not sure what has caused this to happen though ? Was it the viabration going through the push rod the heat or did I have the servo stalling any ways could any one who reads this send some pics of there throtle servo set up so I can compare CHEERS

Are you planning on sending the servo into Horizon to have them check it out?

sounds like 1 of 2 things


1. The servo broke and overheated.

2. One of your endpoints (either idle or full throttle) was overdriving the servo or the motor wouldn't allow the servo to go any further and it wanted to causing the servo to heat up. Typically happens during the setup process but you could have started the damage there and only noticed it later.


Send it in. New servo will be on the way.

Isn't a 8911 just a little overkill for the throttle control.

Yeah prob is but had it there so decided to use it and I dont think I would get anything if I sent it in as sherman89 said its an over kill so its not as if it was working hard lol it was more likely operator error I will put another one in and double check the end points and see what happens

Not saying it happened in this case but I have seen a very large number of throttle linkages that were too long for the amount of servo travel available. That ends up a stalled servo every time and can cook off a servo.

Originally Posted by yxlr8

Yeah prob is but had it there so decided to use it and I dont think I would get anything if I sent it in as sherman89 said its an over kill so its not as if it was working hard lol it was more likely operator error I will put another one in and double check the end points and see what happens

I would still send it in for repair.

How long was your linkage?

Originally Posted by STLAV8R

How long was your linkage?

just askin, what does that matter?

F.T.

I've run across a lot of throttle set ups where the servo linkage was too long for the available servo and throttle lever travels. When they were installed no consideration seemed to have been given to arc radii between the servo and the carb throttle lever. Then insult was added to injury by installing the linkage at the outer most holes on both the servo arm and the carb lever. Some didn't bother to reduce the servo travel from the default 100%.

One of them was so bad, using only bare 4-40 threaded rod, that at either end of the servo arc the load on the rod was so heavy it was bending the ply plate the servo was mounted on. Others were close to doing the same thing in pushing the servo hard to one side at full travels. Those are serious stalled servo conditions and the servos were drawing a whole lof of amps at end travels. Most were high torque digital servos.

That's the kind of stuff smoke and fire is made of, and I've witnessed servos going up in smoke. Both at the servo side and the plug ends. A plug end only goes up in smoke or melts the insulation when the amperage passing through it exceeds about 4.18 amps. That's a lot of current for a single servo and the only way a servo demands that much is through binding and stalling. It really is a very common error.

Now, where's Perth, WA? Perhaps I could take a look at the installation if we are close to each other. I'm in Hood River, OR and fly down at Woodburn, OR a lot. You could also look up Jedijody. He flies out of McKenna, WA much of the time.

Crikey, If that's Perth, Western Australia you're out of luck. edit: Never mind the above, I just saw you signed off with Cheers. You're in Ozzieland.

Crikey, If that's Perth, Western Australia you're out of luck. edit: Never mind the above, I just saw you signed off with Cheers. You're in Ozzieland.

Nah Mate - he's absolutley in Luck - This is the best place to live

Pat - you are welcome to come and visit us here to help us out any time mate. Your knowledge and honest down to earht attitude would be like a breath of fresh air amongst some here.

yxlr8
Was this the servo in the new Krill? (just curious because I have seen that setup and it looked fine at the time - could be end points though - as the others have mentioned)

Hey there Aussie steve yeah its in the Krill we had been playing around with trim and may have set it a bit low I am going to change a few little things and give it another go

Originally Posted by yxlr8

Hey there Aussie steve yeah its in the Krill we had been playing around with trim and may have set it a bit low I am going to change a few little things and give it another go

When you hear that servo screaming and it must have to do damage to itself you gotta' do something. As in all servo set ups you must go full travel and listen and look for binding or servo stall. In order to burn the wires this servo was severely stalled. I am surprised the motor did not burn up.

I use an amp meter and check the reading. It takes all the guess work out of the equation.

Has always been a bullet proof method.

Originally Posted by STLAV8R

I use an amp meter and check the reading. It takes all the guess work out of the equation.

Has always been a bullet proof method.

You took the words right out of my mouth, all my servos are installed and adjusted with the ameter, its 500ma meter . When I mention this to some they say , don't need it, if it buzzes its too much, but hey it will draw too much way before it buzzes...

Roger