servo won't stop spinning
 

It's on a Slo-V that had a fairly rough crash due to a nice gust of wind.
It broke a few teeth on one of the servos. Went to the more than helpful local hobby shop and got a gear set.
Put the gears on and the motor in the servo keeps spinning. There is reaction to controle input, but at center stick the motor spins.
The other servo had no damage and is operating normaly to controle input and is at rest when controler is at center stick.
I figure it must be a simple fix that I don't know about.
I prefer the fix it and find out how it works over replace the part route to trouble shooting.
I've been fixing electronics for over a dozen years so don't be shy with the technical terms.

Thanks Bob

RE: servo won't stop spinning
 

The place to look is the reference potmeter inside the servo. Either there have become slop on the axle between outputgear and pot (propably not) or the brush inside have become loose, dirty or lost tension against the contact surface.
I have done a lot of repairs on ref-pots, but some of the smaller servoes have pots that can`t be opened.
A cleaning and use of SMALL amounts of contact-lubrication have solved most of the problems I have seen. Tiny things inside, hope your eyes are good and you have good working-light and small screwdrivers ;)

RE: servo won't stop spinning
 

2 other things to look at.
When you reinstalled the very top gear, did you line it up correctly? The shaft has a tiny flat spot on it's side, so does the gear. If not correct, and you can force it on incorrect, it will play havoc with the settings.
#2, check the pins on the Rx, where the servo lead attatches,notorious for loose solder joints. As the PZ servos use the Rx for travel limits not the servo. They are a 5 wire instead of normal 3 wire, because of this.

RE: servo won't stop spinning
 

Problem solved Yehaa
I cleaned and lubricated the pot. Being a copier repair guy I have tones of stuff for noisy copiers. Put all the gears back on popped the housing back together. Plugged it back into the controller. Still trying to spin. >the last gear before the mechanical output has a stopper piece built in. I cycled the controller, and it stopped trying to spin the gear past it's stop. PROBLEM SOLVED Yee Freaking Haa. I did open the servo to check no further damage was done due to the motor trying to spin. All looked good, and the stopper part of the final gear was as far as I could eyball dead center. A good 10 min was enjoyed before a rain storm called an end to the test flight.
Thank You jooNorway and Glacier Girl for your help.
It seams the final fix was the Rx's need to receive command from the Tx to esablish a center point for the servo.
Thanks again for the help I had a wonderful all though short flight last night that I otherwise wouldn't have had.:D