1This tutorial explain how to modify BlueBird 660MG+HS servo to work with Antenna Tracker (180 degree rotation)
BlueBird 660MG+HST is strong and robust servo, but need modification to achieve full 180 degree rotation necessary for antenna tracker.
Note: other servos may be modified similar way, but may need other resistor values to obtain full 180 degree rotation.
Prerequisites:
- 2pcs resistors 1kOhm (between 910 Ohm and 1,500 Ohm) 1/4W
- small imbus screwdriver
- Soldering iron, solder, resin etc.
- 3 short, thin wires
- small thermal shrink tube
- tweezers
- small pliers
Unscrew 4 screws at the bottom of servo and remove bottom cap. Take care of thin o-ring when removing cap (it makes servo water proof).
PCB with electronics inside servo case is soldered directly to 3 potentiometer wires, so it is almost impossible to unsolder them, or simply take PCB from case.
Unsolder two wires (red and black) from motor and gently pulling this wires rotate board as on the next pictures. Edges of PCB may be loosely glued to case with drops of glue – you may remove glue with tweezers.
Note: servo case has several parts tied together. You may try to remove two bottom parts as well, to make potentiometer wires more accessible.
After rotating board wou’ll see three wires from potentiometer soldered directly to the PCB. You need to cut this wires using small pliers.
Now solder 2 resistors to two small wires, and solder 3-rd wire directly to middle wire of potentiometer (this wire may be a little longer than others)
Next solder resistors to the side wires of potentiometer.
Put insulating tubes on the wires (and resistors) to avoid shortcuts
Now solder other ends of wires into board. To do it properly first solder motor wires, and then solder 3 wires from potentiometer. Do not cross or mismatch wires!
Put PCB inside case and then put bottom cap. After that put o-ring on its place and tighten all screws.
With 1 kOhm resistors serwo will rotate 180 degree with pulse length range from 950 to 2080 microseconds.
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