Servo Repair
Depending on where you sail (fresh or
saltwater) you may run into problems with your servos. The primary problem is
that water gets into the servos and can cause a number of problems; the most
common is the fouling of the potentiometer witch can be seen as a twitching of
the servo or a failure of the servo all together.
Without getting too technical, the
potentiometer is the device directly connected to the output arm of the servo
that tells the servo where the arm is, compared to where the transmitter is
telling it to be. If this device becomes fouled and communication breaks down
or becomes intermittent, then the servo bounces back and fourth trying to agree
with the transmitter, or it stops completely.
BEFORE you try to repair your
servo, make sure you have made every effort to check that the problem you are
having is not one of the following:
 |
 |
 |
 |
| 1. Remove the bottom
case screws |
2. Remove the top case cover |
3. Remove the gears and shafts
- Take note of the placement of each gear.
This exposes the Pot nut. |
4. Remove the potentiometer
nut and washer |
 |
 |
 |
 |
| 5. Gently
loosen the circuit board and move out of the way exposing the pot. Take
note of the orientation of the pot. |
6. Press the shaft (top) of
the pot. down, forcing the pot into the case. |
7. Carefully
lift the pot. out of the case. Mark the pot. top and
bottom for orientation. |
8. There are three "hold
down" tabs, carefully pry each tab up. |
 |
 |
 |
 |
| 9. Separate the two halves of
the Pot. exposing the contact brushes |
10. Using a soft cloth lightly
wipe the surface of the disk. Do not touch the
brushes. |
11. Put the Pot back together checking
the orientation marks and bend the three tabs back into place |
12. Insert the pot back into
the case, reset the orientation (see#5) and
insert the washer and tighten down the pot nut. |
 |
 |
 |
 |
| 13. Carefully reinsert the
circuit board, align the servo wires and reseat the case bottom. |
14. Turn the case upright |
15. Carefully
reinstall the gears making sure they are seated and turn freely. |
16. Screw in the bottom case
screws. |
Plug the servo back into your receiver and give it a try.
Not all problems with servos can be fixed with this method but
I have found that it has cleared up a number of twitchy servos.
If all else fails give your hobby shop a call and purchase a
new servo.
I hope this page was of some help.
Copyright © 1999 [C.P.M.]. All rights
reserved.
Revised: September 18, 2007