SG90 Servo Has No Signal But Still Buzzes? Don’t Panic, I’ll Teach You How To Solve The Noise Problem

Friends who play Maker must have encountered this situation: there is no signal, or the program has stopped, but the little SG90servoin your hand is still making a "sizzling" sound. The sound may not be loud, but it is really annoying when heard in a quiet environment. More importantly, many friends will worry: Is it broken? Will it burn? Today we are going to talk about this annoying “sizzling sound” and see where it comes from and how to solve it.

Why is the signal still ringing after it stopped?

This is actually not that theservo"does not listen to instructions", but that it is desperately executing instructions. Microservos such as SG90 have a small motor and control circuit inside, which will constantly compare the "target position" and the "current position". When the signal tells it to turn to a certain angle, but it is stuck due to external force, or the internal gear is worn, or even its own strength is not enough, and it cannot reach that point, it will continue to be energized and try to "push" over. This "pushing" action produces the high-frequency current sound we hear.

Will the servo be broken if it makes a sizzling sound?

If this sound occurs for a short period of time, the problem is usually not serious. However, if it is allowed to be in this "hard resistance" state for a long time, the subsequent consequences will be more difficult. This is because when power is continuously supplied, the motor is always in a locked-rotor state, and the current will be relatively large at this time, causing both the control chip and the motor to heat up quickly. Small servos like the SG90 have relatively ordinary heat dissipation conditions. As time goes by, if the situation is mild, the performance of the servos will decrease and the centering will deviate; if it is serious, the internal driver chip will be directly burned out, and the motor will even be "suffocated". Therefore, this sound can actually be regarded as a "distress signal" it sends out.

From another perspective, if you let it "resist hard" with such a sound for a long time, the damage to the steering gear will gradually accumulate. There may be only a slight sound abnormality at first, which seems to be nothing serious, but as time continues, the large current caused by motor stalling has an increasingly obvious impact on the heating of the control chip and motor. Due to the poor heat dissipation of the SG90 servo, this effect continues to intensify. First, the performance of the servo began to decline, and the centering became inaccurate, which was already affecting its normal operation. If it is not dealt with and continues to develop, more serious consequences will occur, such as the driver chip being burned or the motor being damaged. Therefore, this voice is undoubtedly sending a "distress signal" to us, reminding us to pay attention to the situation it is currently facing.

How to judge whether it is a steering gear problem or a program problem?

There is a very simple troubleshooting method. You can first disconnect the signal wire of the servo, leaving only the power and ground wires. If the sound disappears immediately at this time, it is probably because there is something wrong with the PWM signal given in the program. For example, the signal has been jittering, or the given pulse width happens to fall in the critical area between the two angles. If it still sounds after disconnecting the signal line, it may be that there is a foreign object stuck in the internal gear of the servo itself, or the potentiometer is worn, causing inaccurate feedback, causing it to compete with itself.

How to solve the sizzling sound through code

A lot of noise is actually "written" by code. When you give a command to turn the servo to a specific angle, if the pulse width corresponding to the angle value happens to be at the boundary of the "blind zone" of the servo control, then the servo will fine-tune back and forth. To solve this problem, the solution is to directly cut off the signal pin of the servo after it completes its rotation. For example, when using it, add a sentence(, LOW);after executing the.write(angle);statement. In this way, after the servo loses its signal, its internal circuit will stop driving the motor. This not only saves power, but also makes the servo run quieter. When the servo needs to rotate again, just give the signal again.

In addition, in actual operation, this processing method has remarkable effects. After the steering gear loses its signal, the internal circuit stops driving the motor, which indeed achieves the purpose of saving power and being quiet. And when there is a need for rotation later, giving the signal again will allow the servo to work normally. In this way, the back-and-forth fine-tuning phenomenon of the steering gear caused by being at the boundary of the "blind zone" is effectively avoided, making the entire steering gear control system more stable and efficient.

Structural installation will also produce abnormal noise

In addition to electrical problems, improper mechanical installation is also a major source of noise. If you tighten the servo arm too tightly, or the connecting mechanism itself has relatively large resistance, or even if the servo output bearing is subject to lateral force during installation, the internal gears of the servo will not mesh smoothly and the motor will not move. At this time, it will also make a "sizzling" struggling sound. The solution is simple: Loosen the fixing screw, check whether the transmission mechanism is smooth, and try to make the output direction of the steering gear pull or push in a straight line instead of forcefully breaking it.

When is it time to replace the steering gear?

If you have optimized the program and carefully checked and adjusted the mechanical structure, but it still makes a sizzling sound, and you can clearly feel the servo shell is hot when you touch it with your hand, then you can basically judge that there is wear inside the servo or the components are aging. The SG90 itself is an entry-level micro servo. Its metal gears are actually "gold-plated" or made of alloy. It is normal for wear to occur after long-term high-load use.

Faced with this situation, there is no need to worry anymore. Just replace it with a more suitable servo. For example, if you replace it with a servo that uses all-metal gears like the MG90S, its durability will be much better.

Have you ever "overturned the car" in a project due to steering gear noise? Or do you have any unique noise reduction tips? Welcome to leave a message and share in the comment area. If you think this article is helpful to you, don’t forget to give it a like so that more friends can see it!