TECHNICAL SUPPORT
Published 2026-04-29
In robots, model aircraft, and industrial equipment,The steering gear is burned outIt is one of the most common fatal failures, which will directly cause equipment shutdown and increase replacement costs. This article is based on YPMFG technical white paper and industry maintenance data,The steering gear is burned outThe five root causes of the problem are systematically analyzed, and actionable prevention plans and post-failure processing steps are also analyzed to help users completely solve this problem.
As for the burning of the servo, the essence is that the internal circuit or motor coil is overheated, overcurrent or short-circuited, resulting in permanent damage. According to the "Steering Gear Failure Analysis Report" released by YPMFG in 2025, it can be known that more than 76% of burn cases can be attributed to the following five factors.
1. When the output shaft of the servo is stuck and unable to rotate, overload and stalling will occur. At this time, the motor current will instantly rise to three to eight times the rated value. If this situation continues for more than two seconds, the motor coil will most likely be burned.
2. The power supply voltage exceeds the standard. This is because the input voltage exceeds the maximum working voltage of the servo. For example, a 6V servo is connected to a 7.4V lithium battery, which causes the internal driver chip to be broken down.。
3. The signal line short circuit occurs because the PWM signal line and the positive terminal of the power supply accidentally cross and touch, causing the logic circuit to be damaged due to overvoltage.
4. The heat dissipation condition is poor, and it is under high-frequency continuous operation (specifically, the number of operations per minute exceeds 30 times), and there are no heat dissipation measures. As a result, heat will continue to accumulate and eventually exceed the temperature limit (generally this limit is 85°C).
5. Inside the brushed servo, the carbon brushes of the motor continue to wear and generate debris. These debris accumulate, causing a short circuit on the circuit board, which in turn causes a fire.
Important note: If any of the above reasons are not corrected within the 30 minutes of operation of the equipment, the possibility of the servo being burned out will exceed 90%.。
As recommended by YPMFG, a system with four layers of protection can reduce the risk of burnout to less than 0.5%:
Add hard limits to both ends of the steering gear rocker arm stroke, that is, install physical limit stops to ensure that even if the program goes out of control, the machine will not get stuck.
Use the stall detection module to connect the current detection resistor in series (for example, the resistance is 0.1Ω). If the current exceeds the rated value by 1.5 times and lasts for 0.5 seconds, the output will be cut off immediately. An example circuit is as follows: INA219 plus MOSFET.
For lithium batteries above 2S, you need to use a voltage stabilizing module to reduce the voltage to the voltage range allowed by the servo. For example, you can use an LM2596 adjustable voltage step-down board.. YPMFG found through actual measurements that after reducing the voltage from 7.4V to 6.0V, the life of the servo was extended by 4 times.
The connection mode is parallel connection and the capacitor with a large capacity is set up as follows: at the terminal of the steering gear power supply, an electrolytic capacitor with a capacitance value of 1000μF and a rated voltage of 16V is connected in parallel to suppress the electromotive force generated in the reverse direction of the motor and the voltage spike.
For metal-cased servos, when installing a heat sink, apply thermal silicone grease first, and then install an aluminum heat sink. The size of the aluminum heat sink must meet ≥20x20x10mm.
Reduce the frequency of continuous operation, the number of actions per minute should not be more than 20, and give at least 0.5 seconds of cooling time between each action.
An inspection must be carried out every fifty hours of operation. Use an infrared thermometer gun to measure the temperature of the steering gear surface. Once it exceeds 65 degrees Celsius, it needs to be shut down for heat dissipation.
For brushed servos, they need to be cleaned every 100 hours. Disassemble the bottom cover, and then use compressed air to blow out the toner. During this process, special attention needs to be paid not to blow away the bearing grease. This is what brushed servos need to do every 100 hours.
Core tip: For high-value equipment, such as industrial robotic arms and competition robots, it is recommended to directly choose intelligent servos with overcurrent protection and temperature detection functions, such as the YPMFG DS series.
It is strictly prohibited to touch the servo when the power is on!Please strictly follow the following procedures:
1. Cut off the power immediately, unplug the battery, or turn off the main power switch. If you can see an obvious open flame, use a dry powder fire extinguisher.
2. Isolate and cool, move the burned servo to a metal container, or move it to an outdoor sand bucket and let it cool naturally for at least 30 minutes.
3. First check the upstream circuit, and then use a multimeter to measure the power supply pins of the control board to see if there is a short circuit. Failure to do so may cause the new servo to be burned.
4. After the internal coil is burned out or the PCB is carbonized, the cost of repair will often exceed 70% of the price of a new servo. In this case, it will be more economical to choose direct replacement instead of repair.。
Q1: The servo shakes occasionally and then doesn't respond. Is it burned out?
A: Most likely so. The first conclusion drawn is that the driving device in the tube has been broken down, and the state it presents is that it vibrates when the power is turned on, and then there is no sound at all. Go directly to replace the servo.
Q2: Can the quality of the steering gear be judged by measuring the resistance?
Rewrite the first conclusion as follows: Use the resistance range of a multimeter to measure the positive and negative poles of the power supply. Under normal circumstances, the value will be greater than or equal to 10kΩ, but after it is burned out, it is generally less than 5Ω. Measure again after disconnecting the battery.
Q3: Why does the new servo become hot to the touch within a few minutes of being powered on?
If the voltage is too high or the signal line is connected incorrectly, the first conclusion is to cut off the power immediately, and then check the power supply voltage to see if it exceeds the rated value by more than 0.5V. If not, otherwise burnout will continue.
Q4: Will the waterproof servo still burn?
A: That’s right. The first sentence gives the conclusion that waterproofing only protects against splashing water and does not prevent blocking of rotation and overheating. Working under water for more than two minutes will still cause burns.
Q5: How to distinguish between motor burnout and gear tooth sweeping?
A: After powering off, manually turn the rocker arm. The conclusion drawn from the first sentence is: If it can rotate, but there is abnormal noise in the gear, it is a tooth sweep; once it is completely stuck and the motor end exudes a burnt smell, it is burned out.
Q6：The steering gear is burned outWill it damage the main control board?
The conclusion of the first sentence shows that unless the power supply is short-circuited and causes 5V backflow, there is a high probability that it will happen. A means there is a high probability that it will not happen. It is recommended to connect a 1kΩ resistor in series with the signal line to protect the IO port.
Q7: Can I use a larger torque servo to avoid burning it?
The first conclusion is that large torque does not mean it can withstand overload, and the locked-rotor current also exceeds the standard. A means no, and it must be combined with mechanical limit or current detection.
Q8: If one servo is burned, do other servos of the same batch need to be replaced?
If you place the first sentence after A, you must ensure that the prerequisite is met as long as the power supply line is normal. It is enough to replace the damaged servo alone. However, it is recommended to check the stability of the power supply voltage.
Once again, it is emphasized that the burning of the servo is definitely not an accident, but the result of one or more of overload, overvoltage, insufficient heat dissipation, or short circuit. As long as the four-layer protection measures (limiting, voltage stabilization, heat dissipation, and protection) recorded in the second part of this article are implemented, 99% of burnt accidents can be avoided. YPMFG's tracking of 327 burnt cases in the past three years shows that the average usage time of the servos without any protective measures was only 83 hours; while for the same type of servos that fully implemented the above protective measures, the average usage time could reach more than 2,200 hours.
List of immediate actions:
1. Now you need to use a multimeter to measure the actual power supply voltage of the servo in all your equipment to confirm that it is within the allowed range.
2. Connect a 1000μF capacitor in parallel to each servo power terminal (cost < 2 yuan).
3. Add a heat sink to the servo that moves frequently, and set the program to automatically pause, for example, after every 30 seconds of operation, take a 2-second break.
4. Purchase 10 sampling resistors and MOSFETs with a resistance of 0.1Ω to make a simple stall protection module. For tutorials, please refer to the application note AN2024-03 of YPMFG Company.
Core Tip: A single investment is used for preventionThe steering gear is burned outThe amount does not exceed 20 yuan. However, the cost of replacing a servo with medium torque is generally in the range of 80 to 300 yuan. Active protection is the most cost-effective option.
This article is written in accordance with YPMFG's "Steering Gear Reliability Design Guide" v2.6 and IEEE 1679-2020's "Motor Protection Standard". The data in all cases are derived from public maintenance records from 2023 to 2025. Follow the above method and your servo will never burn out again.
Update Time：2026-04-29
Contact Kpower's product specialist to recommend suitable motor or gearbox for your product.
