Troubleshooting RC Helicopter Transmitters & Servos

Written by larry simmons
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Troubleshooting RC Helicopter Transmitters & Servos
Keep your helicopter in the air by troubleshooting problems as they occur. (rc helicopter image by Greg Pickens from

RC helicopters can be difficult machines to control. Advanced models are capable of the same flight characteristics as their life-size counterparts, meaning that instant reaction is necessary to prevent disastrous flight endings. To achieve these instant reactions the helicopter transmitter and servos must act in accord. When the transmitter signal appears not to make it to the model, or when the model only reacts to certain control commands, methodical troubleshooting is in order to correct the problem areas. Through checking the various ways the problem can develop, you can locate and repair the difficulty, returning your model to flight as soon as possible.

Skill level:

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Things you need

  • Working RC helicopter and transmitter
  • Replacement RC frequency crystals

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  1. 1

    Check the power switches on the RC transmitter and the receiver on the helicopter to ensure that both are in the "on" position. Flip the switch on the receiver and check the transmission using both the "on" and "off" positions to make sure the power switch hasn't been wired backwards.

  2. 2

    Turn off the transmitter and receiver. Remove the batteries from both and charge them completely before replacing them and trying the connection again.

  3. 3

    Check that the frequency setting for the transmitter is set the same as the frequency used by the receiver. Examine the frequency crystals inside the transmitter and radio receiver to ensure they have a matching set. You can locate the crystals by looking for small tabs attached labelled RX for the receiver and TX for the transmitter. The crystals have the frequency used stamped onto them. If different, purchase a matching pair and replace the originals. Make sure you've plugged the crystals into the radio securely.

  4. 4

    Find another RC helicopter user flying with the same transmitter frequency as you. Test your transmitter with his helicopter to determine if the problem in yours is within the receiver. Test your receiver with his transmitter to determine if the problem lies with the transmitter. Replace the problem part if one of the combinations works.

  5. 5

    Check the servos for the helicopter if some movements with the transmitter result in a response from the helicopter while others don't. The right stick should change the elevator and aileron, tilting the main rotor blade in the same direction you move the control. The left stick should change the rotor, moving the tailpiece of your helicopter right and left as you move the stick right and left. If one of the controls fails to work, turn off the helicopter and check the servo connected to that helicopter part.

  6. 6

    Examine the physical connection of the troubled servo, make sure the servo connects with the receiver and that the wires aren't broken or frayed. Replace damaged parts and try the connection again.

  7. 7

    Remove the trouble servo with a screwdriver and connect it to a different, working receiver. Turn on the power for the transmitter for the working receiver, and the receiver, then move the transmitter to move your problem servo. If it moves the problem area is with your helicopter's receiver, if it doesn't the servo is bad. Replace the problem part to fix the issue.

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