RC Servo Troubleshooting Guide
A servo motor in an RC car are small motors that are used to operate the throttle and steering on an RC car.
It works by control signals called pulsed signals, which tell the motor where to go and what to do. The signals go through its 3 wires and control the motor.
Servos come in two types – digital and analog.
In this post, we are going to tell you how to solve any problem with the servos of your RC car.
Ready? Let’s dive in.
What Are The Symptoms of RC Servo Failure
If your RC servo is going bad, you will notice the following symptoms:
- Overheating of the servo.
- The servo motor won’t turn.
- The servo twitches or shakes.
- The servo motor makes abnormal noises.
- The servo motor produces reduced torque.
- The servo motor produces smoke.
- Servo produces a funny smell.
- Servo motor dies after reaching a high or full speed.
How to Solve RC Car’s Servo Twitching Problem
The servo works by converting energy from one form to another in a part of the servo called the potentiometer.
When there is dirt or dust in your potentiometer (or ‘pot’), the servo can begin twitching.
How do you fix a twitching servo?
An RC car’s twitching servo can be fixed by two quick steps:
- First, find out what pot has the dirt. There are four pots and two in the servo. The other two are in the transmitter.
To find out what pot has the dust, simply remove the receiver and switch the wires on the receptacles labelled ‘CH 1’ and ‘CH 2’.
Whatever one still twitches is the one with the dirt.
- Second, clean out the dirt. If the issue is with a servo pot, remove the four screws on the bottom.
Be careful that you only remove the bottom section from the servo. Do not remove the whole section.
Remove the circuit board and clean out the dirt.
Whenever the twitching happens, just clean out the dirt. An easy fix.
The Steering Servo Locks Up? It Can Be One of Three Things
This happens when the steering servo does not turn and the steering locks up.
This may be a serious problem, But not necessarily.
How do you fix a steering servo that is locked up?
- check the controller’s Digital Analog Converter (DAC) output. If you find a DAC parameter value of 0 or almost, then the controller is the problem. You need to replace it.
If not, then move to the next option.
- Check the servo itself. Open the case and check that the gears are properly aligned. If they are not, you need a technician to fix it. It should work smoothly after that.
If the gears are properly aligned, then move on.
- Check the case top to see if there is wear. If there is, then you need to replace the case top.
Steering Servo Only Turns One Way, Left or Right
If the steering servo is only turning left or right, you will notice that the steering itself turns only that way.
This is most likely a problem with the servo horn or where the servo trim is centered.
Check the servo horn and all the links. If this is a problem, you need to:
- Make sure that the servo horn is set on the chassis at the correct angle for your car make and model
- Then, make sure all the links are the right size and respond smoothly to directions from the servo
However, fiddling with the servo so much may complicate the process, so changing the servo motor is the best and easiest bet.
My RC Car Go Forward When I Turn
A faulty servo is usually responsible for this problem if it happens.
But however, it does not always mean a faulty servo. It could be a problem with the transmitter. So you need to test it out.
Disconnect the steering servo from the receiver.
Then try to turn the steering again by twisting the wheel to any direction you want.
If everything turns okay without moving forward, then you have a faulty servo.
A technician can help you repair the servo, or you can replace the servo entirely.
What Can I Do If My RC Servo Is Not Centering
You can fix an RC servo that does not center with a servo tester.
A servo tester can be purchased easily online.
Once you have the servo tester, remove the servo.
Then, put the servo arm on as close to 90 degrees as possible. Then plug in your servo to your servo tester by plugging the wires to the appropriately named labels on the tester.
Then plug a battery (your RC car battery is best) into the tester through the positive and negative rails.
Then set the servo tester to neutral. This adjusts the servo arm to the center. Screw the arm into the servo to lock it in, and voila! Servo centered.
If this explanation seems too complicated, this video does a really good job of explaining it. It’s short and straight to the point.
How To Reset A Steering Servo
Resetting a steering servo on an RC car is fairly easy to do. Here’s how:
- Detach the servo from the steering system. You just need to remove one screw for most RC cars.
- Then, plug the car in and turn it on, making sure the servo is still connected.
- Ensure that the trim on the transmitter is centered.
- Then make sure the wheels are perfectly aligned. Make them as straight as possible.
- Test it out to see that the steering turns well in either direction.
- Then screw the servo back on.
RC Steering Servo Not Responding? Lets Find Out Why And Fix It
Where your RC steering servo is not responding at all, it is usually a sign that you need to change the servo.
However, you must be sure that it is not the receiver affecting the servo by testing out the receiver.
- First, unplug the servo that is not working from the receiver.
- Then unplug the throttle or brake servo
- Plug the servo that is not working into a different channel. Remember the CH 1 and 2 we earlier mentioned? That’s where you’ll plug the servo into. Plug it into CH 2 if it is 1 that isn’t working and vice versa.
- Operate the throttle trigger to test the steering servo.
If the servo still does not work, then it is bad and needs to be changed.
Top Tip: How Do I Clean an RC Servo?
Here’s how to clean an RC servo:
- Open up the servo motor. Detach if you can.
- Use a paper towel to CAREFULLY wipe off the different parts of the servo. Use ordinary alcohol as a cleaning solution. It works fine.
- Take extra care around the copper contacts and the wires so as not to damage them.
- When your servo is sufficiently clean, put it back in
Your servo is now clean and should work fine.
Do RC Servos Go Bad?
Yes, RC servos go bad. It can develop issues that can make it unusable or in need of repairs.
Also, a servo motor mostly has a shelf life of 20 years, although if an RC car goes through abuse, the problems may come much sooner.
The servo is one of the most delicate parts of the RC car’s internal components. It should be handled with care.
If you are not sure of what to do about a servo problem, we strongly advise that you contact a technician.