Radio Control Systems - Modification of Protech/Ripmax SD150/200 Servo

The following shows how to modify this type of servo for 360 degree rotation. In this case, we are using an SD150 servo. It is not exactly the same as an SD200, but certainly the approach is similar.

Step-by-step - Antweight servo modification

Follow steps exactly, taking care and time over the job. Click on any picture to magnify and study carefully. Job should take between 10 and 30 minutes. Tx - Transmitter, Rx - Receiver, Creep refers to servo movement when it should be stationary. A certain amount of creep is to be expected on modified servos.

1. Remove 4 fixing screws from base to release top and bottom sections. 2. Remove the bas and take all the bits out. (For SD200, only remove the gears.) 3. Connect the servo to an Rx and with the Tx on and all trims set to neutral, turn the pot (yellow in picture) until motor stops turning.

3a. In the case of the SD200, the yellow cap sits under the main output gear. Simply remove the yellow cap (its only pushed on) and turn the pot with a small screwdriver. 4. Once set in place, remove the yellow cap and the board can be returned into the casing (SD150 only). 5. Check the top for any physical 'stops' and remove as needed. On the SD200, the stop is on the output gear. This can be cut off with a scalpel or Dremel.

6. Replace the gearset into the top of the case. The top should then be carefully replaced on the servo body. 7. Replace all screws and fittings. The job is complete. Check that there is no major creep when connected. If necessary go back and reset the pot.