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As a decade-long veteran in the power supply sector, our company has recently sparked significant industry attention through the exceptional performance of our core products. Rooted in technological innovation, we specialize in delivering high-quality power solutions that combine reliability, efficiency, and cutting-edge design. Our diverse portfolio—including Power Adapters, AC DC Adapters, DC Adapters, and Fast Chargers—has earned widespread acclaim in global markets for driving seamless connectivity and energy efficiency across devices.   Core Product Lineup: Redefining Power Supply Standards Power Adapter: The Industry Benchmark Our Power Adapter stands as a testament to engineering precision. Leveraging advanced circuit design and premium components, it achieves ultra-high energy conversion efficiency (up to 95%) and stable voltage output, even under fluctuating loads. Equipped with multi-layer safety protections—overvoltage, overcurrent, short-circuit, and thermal shutdown—it acts as a "smart guardian" for devices ranging from LED lighting to IT equipment. Its compact form factor and universal input (100-240V) make it an ideal choice for global applications, ensuring safe, low-noise operation in any environment. AC DC Adapter: Compact Powerhouse for Diverse Industries The AC DC Adapter embodies "big power in a small package." With a high power density of up to 50W/in³ and a wide input voltage range (90-264V AC), it seamlessly adapts to industrial control systems, communication networks, and smart home devices. Its ruggedized design withstands harsh conditions, while advanced EMI suppression technology ensures compliance with global EMC standards. For manufacturers seeking reliable power "heartbeats" for their equipment, this module delivers consistent performance across temperature ranges (-20°C to +70°C), making it a trusted backbone in critical applications. DC Adapter: Versatility Meets Stability Designed for precision-driven systems, our DC Adapter offers customizable voltage outputs (5V-48V DC) with tight regulation (±1%). Whether powering medical devices, industrial automation equipment, or outdoor surveillance systems, its low ripple and noise characteristics guarantee stable operation. The adapter’s intelligent thermal management system prevents overheating, while its plug-and-play compatibility reduces integration complexity for OEM partners. It’s not just a power supply—it’s a reliable foundation for device longevity. Fast Charger: Accelerating the Future of Charging Our Fast Charger combines speed and smarts to revolutionize charging experiences. Supporting protocols like PD 3.0 and QC 4.0, it delivers up to 100W of power, reducing charging time for laptops and electric vehicles by 50% compared to traditional chargers. The built-in intelligent IC identifies device types in real time, optimizing current output to prevent overcharging and battery degradation. Whether for smartphones, drones, or e-bikes, this charger balances efficiency with safety, making it an indispensable companion in the era of smart mobility. Innovation-Driven R&D and Automated Manufacturing At the core of our success is a world-class R&D team comprising senior power supply engineers with over a decade of industry experience. Collaborating with leading universities and research institutions, we continuously innovate in areas like GaN-based high-frequency conversion and energy storage systems. This enables us to launch 3–5 new products quarterly, ensuring our Power Adapters, AC DC Adapters, and Fast Chargers always incorporate the latest breakthroughs—from ultra-compact GaN designs to solar-powered charging solutions. Our automated manufacturing ecosystem further reinforces quality and scalability. With 6 fully automated production lines and AI-driven quality control systems, we achieve a 99.8% first-pass yield while reducing production costs by 30%. Every product undergoes rigorous testing—including 48-hour burn-in, surge protection, and environmental stress screening—ensuring compliance with UL, CE, FCC, and RoHS standards. Global Market Presence and Customer Trust Our commitment to excellence has propelled our products into 80+ countries across Europe, North America, Asia, and Africa. At international exhibitions like the Consumer Electronics Show (CES) and Electronica, we showcase how our AC DC Adapters power smart cities, our DC Adapters enable industrial IoT, and our Fast Chargers support electric mobility ecosystems. This has forged long-term partnerships with Fortune 500 companies and leading SMEs alike, who rely on our solutions to enhance their product competitiveness. In overseas markets, our localized service teams provide pre-sales technical support and post-sales maintenance, ensuring seamless integration and customer satisfaction. Whether powering a European smart home or an African renewable energy project, our adapters and chargers are trusted to deliver consistent, efficient performance.   We look forward to jointly shaping the next generation of power innovation. Together, we can advance progress.

Detecting the output voltage of an AC-DC power adapter using a multimeter Detecting the output voltage of an AC-DC power adapter using a multimeter is a common and effective method.   First, plug the power adapter into an outlet and connect the output end of the adapter to the multimeter. When selecting the DC voltage (DCV) measurement function, choose a higher range to ensure that it can accommodate possible higher voltage values. For example, if the nominal output of the adapter is 12 volts, a 20-volt range can be selected. Connect the black test lead to the COM port (common ground) on the multimeter and the red test lead to the VΩmA port (DC voltage/resistance/milliampere). After the plug is correctly connected, wait for a few seconds before disconnecting the connector to ensure stable operation. Use the red test lead to touch the positive terminal on the output terminal of the adapter and use the black test lead to touch the negative terminal. During this process, pay attention to maintaining good contact and stability. Hold the two test leads for a few seconds and record the reading.   If it is in DC mode, a specific number will be displayed; if it is in AC mode, a waveform or average value will be displayed. Compare it with the reading that should be within the nominal voltage range of the adapter model as you know. If the reading is close to the nominal voltage, it indicates that the adapter is working well; if the reading deviates too much, it may indicate that there is a problem with the adapter. In addition, the following method can also be used for detection. Set the multimeter to voltage test mode, select the output voltage range of the adapter, and then connect the red and black test leads to the positive and negative poles of the adapter respectively. Read the displayed voltage value to ensure that it is within the nominal voltage range of the adapter. If it is necessary to test the current, set the multimeter to current test mode and connect it in series to the output circuit of the adapter. Read the displayed current value to ensure that it is within the nominal current range of the adapter. When testing, be sure to ensure that the power adapter is powered off to prevent short circuits and equipment damage. Observe fault phenomena to determine the cause of abnormal output voltage When the output voltage of an AC-DC power adapter is abnormal, some fault phenomena can be observed to preliminarily determine the cause. If the power adapter cannot output the required power, it may be due to a failure of the power adapter itself, such as damage to internal components, loose line connections, etc.; it may also be due to the disconnection or damage of the connection between the power adapter plug and the battery; or the input voltage of the power adapter is unstable or exceeds the limit. If the output voltage is unstable, it may be due to damage or aging of the capacitor of the power adapter, or poor contact of the transformer winding of the power adapter. If the output voltage is too high or too low, it may be due to aging or damage of circuit components of the power adapter, or too large a load current of the power adapter, or a failure of the output voltage regulator of the power adapter. If the power adapter overheats, it may be due to poor internal heat dissipation of the power adapter, or a short circuit or heavy load of the power adapter.

How can we judge the heat dissipation performance of an AC-DC power adapter? We can start from the following aspects: 1. Check product parameters and specifications Observe the thermal resistance index: Thermal resistance is an important parameter for measuring the heat dissipation capacity of a power adapter. The lower the thermal resistance, the stronger the adapter's ability to conduct heat from the inside to the external environment during operation, and the better the heat dissipation performance. For example, some high-quality AC-DC power adapters may clearly mark the thermal resistance value in the product manual. If the thermal resistance is within a relatively low range, such as several tens of degrees Celsius per watt or even lower, it usually means that the adapter has better heat dissipation performance. Pay attention to the operating temperature range: The operating temperature range reflects the ability of the power adapter to operate normally under different environmental temperatures. A power adapter with good heat dissipation performance usually has a relatively wide operating temperature range. For example, the operating temperature range of some adapters can be from -20°C to +70°C or even wider. This indicates that under relatively extreme temperature conditions, the adapter can still maintain stable performance, indirectly indicating its stronger heat dissipation ability. 2. Check product design and structure Shell material and design: High-quality shell materials are helpful for heat dissipation. Metal shells usually have better thermal conductivity than plastic shells. For example, an aluminum shell can quickly conduct the heat generated inside to the outside, thereby improving heat dissipation efficiency. In addition, the design of the shell is also very important. Some adapters may have design elements such as heat sinks and ventilation holes on the shell. Heat sinks can increase the heat dissipation surface area, and ventilation holes help air circulation and take away heat. Internal layout and component arrangement: A reasonable internal layout can reduce heat concentration and improve heat dissipation effect. For example, distribute components with large heat generation to avoid being too concentrated in one area. At the same time, the spacing between components will also affect heat dissipation. Sufficient spacing can allow air to circulate better and take away heat. If the internal components are arranged closely, it may lead to heat accumulation and a decrease in heat dissipation performance. 3. Observation and testing in actual use Touch to feel the temperature: After the adapter has been working for a period of time, touch its shell with your hand. If the shell is only slightly warm, it indicates good heat dissipation performance; if the shell is very hot and even makes it impossible to touch for a long time, then there may be a problem with heat dissipation. However, it should be noted that when touching, ensure safety and avoid the risk of electric shock. Use professional equipment for testing: Professional equipment such as infrared thermometers can be used to measure the surface temperature of the adapter during operation. By comparing the surface temperatures of different adapters under the same working conditions, the heat dissipation performance can be intuitively judged. In addition, equipment such as power meters can be used to monitor the input power and output power of the adapter and calculate its efficiency. Adapters with high efficiency usually generate less heat and have relatively less heat dissipation pressure. 4. Refer to user evaluations and professional evaluations Check user evaluations: Before purchasing an AC-DC power adapter, you can check the evaluations of other users on e-commerce platforms, forums and other channels. The feedback of users in actual use can often provide important information about the heat dissipation performance of the adapter. If most users report that the adapter does not heat up significantly during use or give positive evaluations of its heat dissipation performance, then the heat dissipation performance of the adapter is likely to be relatively reliable. Refer to professional evaluations: Professional electronic product evaluation agencies will conduct detailed tests and evaluations on various power adapters, including tests of heat dissipation performance. You can refer to these evaluation reports to understand the heat dissipation performance of different brands and models of adapters. Evaluation reports usually provide objective data and analysis to help you make more accurate judgments. How can we choose a power adapter with an appropriate output power according to the power requirements of the device? What will happen if the output voltage of the power adapter does not match the input voltage of the device? Which brands of AC-DC power adapters have better heat dissipation performance?

For low-power AC-DC power adapters, the selection of control IC is crucial. Different control ICs have different characteristics and performances, and need to be selected according to specific application requirements. For example, some control ICs have a built-in soft start function, which can reduce the stress on the MOSFET and improve the reliability of the power adapter. At the same time, the built-in slope compensation circuit can improve the stability of the power adapter. In addition, the switching frequency is also an important consideration. A higher switching frequency can reduce the volume and weight of the power adapter, but it will also bring some problems, such as increased electromagnetic interference. Therefore, a trade-off needs to be made between volume, weight and electromagnetic interference. Some control ICs have a frequency jitter function, which can give it good EMI characteristics. When selecting a control IC, its protection functions also need to be considered. For example, protection functions such as over-temperature, over-current, over-voltage, and under-voltage can ensure the safe operation of the power adapter under abnormal conditions. At the same time, the cost and availability of the control IC also need to be considered. Some well-known brand control ICs may have higher performance and reliability, but the price is also relatively high. When selecting a control IC, comprehensive consideration can be made according to actual needs. To sum up, choosing a suitable AC-DC power adapter needs to consider multiple factors, including equipment power requirements, voltage and current matching, efficiency and other indicators, output connector selection, and control IC selection for low-power AC-DC power adapters. During the selection process, you can refer to the equipment's instruction manual, consult professionals or consult relevant technical materials to ensure that you choose a power adapter that meets your needs. For example, if the equipment requires a large current output, then an output connector that can withstand a large current should be selected. At the same time, the quality and durability of the output connector also need to be considered. Some output connectors of poor quality may have problems such as poor contact and loosening, which will affect the normal use of the equipment. In addition, you can also consider choosing an output connector with some special functions, such as a connector with a locking function, which can prevent accidental disconnection; a connector with an indicator light can conveniently determine whether the power adapter is working properly. When choosing an output connector, you can refer to the equipment's instruction manual or consult a professional to ensure that you choose the right output connector. Brand and quality considerations Choosing an AC-DC power adapter from a well-known brand is often more guaranteed. Well-known brands usually invest more resources in research and development, production and quality control, and their products have undergone strict testing and certification. For example, some international well-known brands will conduct a large number of reliability tests in the product design stage, including performance tests in environments such as high temperature, high humidity, and vibration to ensure that the product can work normally under various harsh conditions.

In the realm of electronics, power adapters play a crucial role in converting AC power to DC power, enabling the operation of various devices. However, a common challenge associated with power adapters is noise generation, which can interfere with the performance of other electronic components and create unpleasant sounds. YHYadapter, a leading provider of high-quality power solutions, is committed to addressing this issue by implementing innovative noise reduction techniques, ensuring a quieter and more harmonious electronic environment. Combating Noise Pollution with Advanced Filtering YHYadapter employs a multi-stage filtering approach to effectively eliminate noise across a wide range of frequencies. These filters, meticulously constructed using capacitors, inductors, and resistors, act as barriers, preventing unwanted frequencies from disrupting the power supply. This sophisticated filtering mechanism ensures that only clean, noise-free power reaches the connected devices. Shielding: A Barrier Against Electromagnetic Interference To further combat noise pollution, YHYadapter utilizes a robust metal shielding enclosure. This protective barrier effectively blocks electromagnetic interference (EMI), preventing external noise from infiltrating the power supply and causing disruptions. The meticulous shielding design ensures that the power adapter operates in a quiet and interference-free environment. Grounding: Establishing a Common Reference Point Proper grounding plays a pivotal role in minimizing noise levels within power adapters. YHYadapter features a well-designed grounding system that connects the power supply to a common reference point. This grounding mechanism effectively eliminates noise currents, ensuring that only clean and stable power is delivered to the connected devices. Soft-Start Circuits: A Gentle Approach to Power Delivery To further reduce noise generation, YHYadapter incorporates soft-start circuits. These circuits gradually increase the voltage to the power supply's output, effectively eliminating inrush current, a common source of noise. This gentle approach to power delivery ensures a smooth and quiet operation, minimizing any potential disruptions. Optimized Switching Frequency: Striking the Balance The switching frequency of a power adapter significantly impacts noise levels. YHYadapter power adapters carefully optimizes the switching frequency, selecting a value that effectively reduces noise without compromising overall efficiency. This meticulous optimization ensures that the power adapter operates at a level that is both quiet and efficient. YHYadapter: A Commitment to Noise Reduction YHYadapter is unwavering in its commitment to providing high-quality, efficient, and reliable power solutions. The company's dedication to noise reduction is evident in its innovative filtering techniques, shielding mechanisms, grounding systems, soft-start circuits, and optimized switching frequencies. These advancements ensure that YHYadapter not only deliver clean and stable power but also contribute to a quieter and more harmonious electronic environment.

As a leading player in the power adapter industry, YHYadapter has been committed to continuously improving supply chain efficiency and cost management to ensure robust business development and a firm market position. Below, we will explore the key initiatives of YHYadapter in supply chain and cost management, empowering the company to achieve greater accomplishments. YHYadapter constantly introduces new equipment to achieve the mechanization and intelligence of the production process, enhancing production efficiency and reducing production costs. Moreover, the company focuses on enhancing employee professionalism through training and skills enhancement programs to ensure smooth production processes. YHYadapter continuously optimizes cost management, focusing on enhancing research and development capabilities and technological innovation to provide more competitive products. By reducing production costs and management expenses, YHYadapter ensures the reasonableness of product prices and market competitiveness. YHYadapter is committed to building an efficient and stable supply chain and excellent cost management system to continuously improve product quality, enhance customer satisfaction, and achieve sustainable development goals. In the future, the company will continue to uphold the spirit of innovation, constantly driving progress in supply chain and cost management to create greater value for customers.

1, no output, safe tube normal This phenomenon indicates that the switching power supply is not working or entering a maintenance condition. First, it is necessary to measure whether the starting pin of the power control chip has a starting voltage. If there is no starting voltage or the starting voltage is too low, it is necessary to check whether the starting resistance and the components connected to the starting pin are leaking. At this time, if the power control chip is normal, the fault can be quickly detected by the above check. If there is starting voltage, measure whether the output end of the control chip has high or low level jumps at the moment of starting up. If there is no jump, it indicates that the control chip is bad, the peripheral oscillating circuit element or the maintenance circuit is faulty. You can replace the control chip first, and then check the peripheral component. If there is a jump, generally bad or damaged switch tube. 2, safely burn or fry Mainly check the large filter capacitor on 300V, rectifier bridge diode and switch tube and other parts, anti-interference circuit problems will also lead to safe burning, black. The need to note that: due to the breakdown of the switching tube caused by safe burning will generally burn the current detection resistor and power control chip. Negative temperature coefficient thermistors are also easily burned out with safety. 3. There is output voltage, but the output voltage is too high This kind of fault generally comes from the stable voltage sampling and the stable voltage control circuit. In the DC output, sampling resistance, error sampling amplifier such as TL431, optical coupler, power control chip and other circuits together to form a closed control loop, any problem will lead to the output voltage rise. 4. The output voltage is too low In addition to the voltage regulator control circuit will cause the output voltage low, there are the following reasons will also cause the output voltage low: a, the switching power supply load has short circuit fault (especially DC/DC converter short circuit or poor function, etc.), at this time, should disconnect all the load of the switching power supply circuit, in order to distinguish the switching power supply circuit is still the load circuit fault. If the voltage output of the disconnected load circuit is normal, it indicates that the load is too heavy; Or still not normally clarify the switching power supply circuit is faulty. b. Failure of rectifier diode and filter capacitor at output voltage end can be judged by substitution method. c, the function of the switch tube decline, inevitably lead to the switch tube can not be normally switched on, so that the internal resistance of the power supply is added, can be reduced with load. The above 4 small failures are relatively easy to occur, we will continue to share for you in the future, to help you save resources, better use of switching power!

I. The superthermal efficiency or over AC current limit of pulse width by pulse width In the new product research and development process of the knob power adapter, the superthermal efficiency and over AC current limit one pulse width by one pulse width are indispensable, and this kind of superthermal efficiency or over AC current limit one pulse width by one is a very reasonable way to output overvoltage protection in the specific application. This process is often used in the extra sub-side current limiting maintenance. In practical application, it is a very reasonable way of output overvoltage protection, which is often used in the maintenance of additional subside current limiting. In the previous switchgear, the AC input was monitored in real time. If this alternating current exceeds the required limit current value, the on-pulse width will stop. In the continuous flyback converter, its larger alternating current determines the thermal efficiency of integrated operational amplifier, and this kind of maintenance integrated operational amplifier becomes a true thermal efficience-limited maintenance integrated operational amplifier. Two, the super thermal efficiency of the time off maintenance As a very reasonable output overvoltage protection technology, super thermal efficiency time-off maintenance has been widely promoted in China's power adapter products. In a time-hopping system, the provision of temporary transient alternating current is permitted, and the alternating current can only be turned off when the shear force exceeds the safe value for a long period of time. The presentation of short transient alternating current will not easily harm the credibility of the generator, nor will it easily harm the profit of the generator. Only the requirement of continuous AC power for a long time will jeopardize the profit and volume of integrated operational amps. 3. Flyback superthermal efficiency limit Protection Law In addition to the two methods described above, flyback ultra-thermal efficiency limit protection law is also a key strategy to reasonably ensure the safety of knob power adapter production work, currently in China's adapter development and manufacturers in the process of processing is more common. This type of maintenance process is an extension of the up-speed approach. In adaptor integrated operational amps with this protection, a specialized integrated operational amp monitors the primary AC and secondary side currents, reducing thermal efficiency as the output current decreases. According to this way, when the load resistance drops, the output alternating current is reduced to avoid the side electronic devices suffer from too strong shear force harm, its defect is used to discrete the system load when the locking condition. Iv. Constant thermal efficiency limit protection Law Uniform motion typing thermal efficiency limit protection law is the fourth kind of knob power adapter maintenance technology that people will introduce today. It is the output maintenance technology that is more practical in the world at this stage. It is unavoidable in the development process of the laptop adapter and its computer adapter. The maintenance mechanism of this type of mode depends on maintaining the primary integrated operational amp according to the limited large transfer heat efficiency. However, in flyback converter, this kind of process basically can not maintain the side output components. For example, in a continuous flyback converter, the original edge value AC is already limited, and the transfer heat efficiency is also limited.

The power adapter is an indispensable electronic product in our life, we will charge it almost every day, although it looks like the design is very simple, but in fact the power adapter is also composed of many precise electronic components, simple division, there should be four major components, today the charger manufacturers and you talk about the power adapter what components? What problems should be paid attention to potting glue? The four components of a power adapter 1. Main circuit: mainly includes the following parts (1) Impulse current limiting: limit the impulse current of the input side at the moment when the power is switched on. (2) Input filter: its function is to filter the clutter of the power grid and prevent the clutter generated by the machine from being fed back to the power grid. (3) Rectification and filtering: the AC power supply of the power grid is directly rectified into smooth direct current. (4), inverter: the direct current after rectification into high frequency alternating current, which is the core part of high frequency switching power supply. (5) Output rectification and filtering: provide stable and reliable DC power supply according to load needs. 2, control circuit: on the one hand from the output end of the sample, compared with the set value, and then to control the inverter, change its pulse width or pulse frequency, so that the output stability, on the other hand according to the data provided by the test circuit, through the protection circuit identification, to provide a variety of protection measures for the power supply control circuit. 3, detection circuit: provide protection circuit in operation of various parameters and various instrument data. 4. Auxiliary power supply: realize the software (remote) startup of the power supply, and supply power to the protection circuit and control circuit (PWM chip). Power adapter potting glue need to pay attention to what problems? 1, waterproof, potting glue will be the electrical part of the power adapter tightly wrapped, completely isolated from the outside world; What water, water, acid, alkali and salt can not get to the circuit element, can improve the ability of waterproof, moisture-proof and anti-corrosion. So you choose the glue to good liquidity, liquidity is not good how can deep penetration completely sealed; Moreover, the bonding force should also be available, otherwise, after sealing for a long time, the alternating hot and cold and component separation is useless, and the service life performance of the power adapter is also affected. 2, thermal conductivity, power adapter is a work rate product, that is, conversion, control, output energy. Adaptor work to heat, such as switch tube, transformer, electrolytic capacitor, inductance, which is not heating devices and are afraid of heat devices. What to do? We must transmit the heat as quickly and as much as possible. So the glue must have good thermal conductivity, it can be said that the higher the thermal conductivity of the expected glue, the better. The life of the electrolytic capacitor in the power supply shrinks by half with every increase of ten degrees of temperature, but you can't add heat sink to it; Transformer, inductance temperature a high many parameters are changing the whole design is difficult to improve, you are not good to add a heat sink to him. 3, insulation strength, basically all glue is not conductive, but pay attention to, like epoxy class AB glue curing reaction is not completely may be a little local conductive. And in order to save the sand in it, that is hard to say. First, your sand is not dehydrated processing, but also your sand will some other elements interfere with the curing; Whether the ratio of AB agent is reasonable, whether the mixture is sufficiently uniform, and whether other conditions are met. 4, environmental protection requirements, adapters are generally certified. It depends on whether the products provided are consistent with the certification. The price difference between environmental protection and non-environmental protection materials is still quite a lot. 5, flame retardant requirements, generally look at the flame retardant test in UL. General requirement 94-V0 above.

Laptop power adapter is a common tool, but do you know its construction? What is the construction of the notebook power adapter? What are the pieces after you disassemble them? Let's take a look today! What is the construction of the notebook power adapter? What are the pieces after you disassemble them? 1. Varistor, its function is that when the external voltage is too high, the varistor resistance value becomes very small rapidly, and the fuse in series with the varistor is blown, so as to protect other circuits from being burned out. 2. Fuse, specification is 2.5A/250V, when the current in the circuit is too large, the fuse will be blown to protect other components. 3, inductance coil (also known as choke coil), the main function is to reduce electromagnetic interference. 4, the rectifier bridge, the specification is D3SB, the role is to change 220V alternating current into direct current. 5, filter capacitor, the specification is 180μF/400V, the role is to filter the AC ripple in DC, so that the circuit work more reliable. 6, operation amplifier IC(integrated circuit), an important part of the protection circuit, voltage regulation. 7, the temperature probe, used to detect the internal temperature of the power adapter, when the temperature is higher than a certain set value (different brands of power adapters, the set temperature threshold is slightly different), the protection circuit will cut off the voltage output of the adapter, so as to protect the adapter from damage. 8, high power switching tube, is one of the core components of switching power supply, switching power supply can "open and close" to work, the switching tube is indispensable. 9. Switching transformer, one of the core components of switching power supply. 10, secondary rectifier tube, function is to change low voltage alternating current into low voltage direct current. In IBM's power adapter, the rectifier tube is often operated in parallel by two large power units to obtain a large current output. 11. There are two secondary filtering capacitors, 820μF/ 25V, which can filter the ripple in low-voltage DC. In addition to the above components, the power adapter circuit board also has adjustable potentiometer and other resistance and tolerance components.

Before choosing a charger, we should first judge whether the charger is suitable, and then consider its quality and so on. So how do you know if the charger will charge your phone quickly? How to choose? First, how to judge the charger can give the phone fast charge? 1, check whether there is a common fast charge agreement between the charging device and the mobile phone, if there is generally can use the fast charge function. 2. Common fast charge protocols include Qualcomm QC3.0/QC2.0, USB PD, Huawei FCP, Huawei SCP(SuperCharge), Mediatek MTK PE(Meizu mCharge), Samsung AFC, DASH(VOOC) flash charge, etc. Common non-fast charge protocols include Apple 2.4A, USB DCP, BC 1.2 and so on. 3, fast charge agreement as a product selling point, manufacturers will generally be marked on the packaging, if not found, you can go to the charging head network official website, search for the model and other keywords, that is, you can also find the answer in the mass of original evaluation dismantling. 4. If you are a geek, you can also use the instrument tool (ChargerLab power-z KT001 portable USB PD tester) to quickly identify which charging protocols are supported by the charger/POWER bank. Two, how to choose the charger? 1. Charger voltage: At present, there are two types of indoor voltage used in the world, which are 100V ~ 130V(low voltage input) and 220 ~ 240V(high voltage input). 100V: Japan and Korea. 110 ~ 130V: 30 countries including Taiwan, the United States, Canada, Mexico, Panama, Cuba, and Lebanon. 220 ~ 230V: China, Hong Kong (200V), the United Kingdom, Germany, France, Italy, Australia, India, Singapore, Thailand, the Netherlands, Spain, Greece, Austria, Philippines, Norway about 120 countries. 2. Charger plug: The GB plug is used in China, Australia, New Zealand and Argentina and features two flat heads. The American standard plug is used in the United States, Canada, Japan, Brazil, the Philippines, Thailand and other countries and Taiwan, characterized by two flat inserts with holes, similar to the national standard, can also be used in China. The British standard plug is used in Hong Kong and the United Kingdom, India, Pakistan, Singapore, Malaysia, Vietnam, Indonesia, Maldives, Qatar and other countries and regions, featuring three square heads. European standard (German standard) plug in Germany, France, the Netherlands, Denmark, Finland, Norway, Poland, Portugal, Austria, Belgium, Hungary, Spain, Sweden and other European Union countries and South Korea, Russia and other countries used, characterized by two round heads. South African standard plug is mainly used in South Africa, India, Russia, features three round heads. There are Italian standard (Italian standard) plug, Swiss standard (Swiss standard) plug. The same country or region also uses a variety of standards. 3. Reasonable selection of product schemes: If you don't have a charging indicator on your product, you can choose a charger with a turn light, which is red when charging and full of turn green light. If the product itself has a charging indicator function, choose the charger of the ordinary indicator light can be, do not have to worry about overcharging. Because today's phones and chargers have automatic protection features, a full charge will only have a small current to trickle the battery charge. The selection of the scheme because there are too many products involved, here is not a list, the specific situation please contact our business specialist to choose for you. 4. Output mode Basically there are two kinds, one is USB interface, this is the most commonly used, with the output interface specifications of the same computer. The other is the output of the line, the line joint depends on the interface of the product you want to support, generally are standard parts, the line joint is customized according to customer requirements. Correct judgment and choice of charger can effectively prolong the service life of equipment, but also better guarantee the quality of charger, to ensure the normal charging of mobile phone!

Mobile phone, computer, tablet, battery car, flashlight and so on these need switching power supply, and in life switching power supply everywhere, its model is more, and different power, although some can be universal, but under normal circumstances or according to the situation to use a special switching power supply. There are many types and brands of this kind of products in the market. Consumers generally need to select according to their own needs when choosing, or let businesses directly help us to recommend, so that they can quickly complete the purchase and will not affect our daily use. But if the quality of the selected switching power supply is not good, it is not only a waste of switching power costs, and may allow other electronic products to be damaged. So we must carefully choose the right brand, but also to understand some selection skills. First, be clear about your needs. Under normal circumstances, we only think of buying switching power when the products we use fail. We can directly take the previous adapter to the corresponding store to buy. Basically selling electronic products or repair shops will have this kind of switching power supply, the price is about dozens of yuan to one hundred yuan, is not a very high price. And if you do not know what type of switching power supply you used before, then it is best to directly take their own use of products to the store to buy, try switching, switching power really meet our requirements after the purchase, so that you can avoid unnecessary trouble. Second, choose the right brand. The brand of switching power supply is still more, and its service life is also relatively long, like the mobile phone power supply may be used several times a day, if its quality is not high, it is easy to have problems. I believe you are more willing to buy high-quality products, although the price of switching power supply on the market is about dozens of yuan, but because we want to compare the pros and cons of the product is still a certain difficulty, so we must choose brand products. The products of big brands or big manufacturers are tested by the authority department. The quality of their products is better. Although the unit price is slightly higher, there will not be much difference in price, which is more suitable for us to choose. Third, determine the after-sales service. Switching power supply can basically be used for a few years, of course, this is to buy the product is a regular product on the basis of the long service life can be guaranteed. However, when we buy such products, it is best to confirm the after-sales service with the merchants. If there is a problem within a month of use, the merchants should provide unconditional replacement of the new products or help us carry out maintenance. It is not recommended to choose non-brand three no products, this kind of product quality is likely to have problems, and may even threaten our safety, and can provide better after-sales service business products are more quality assurance. Personal purchase of switching power must choose professional products, brand products are about twice as expensive, but such products are more worthy of our trust, its use effect is better, but also more secure. And some high quality products produced by large manufacturers will not be too much higher prices, but also can ensure the use of products, more worthy of our trust. If you want to wholesale this kind of product, you must choose a variety of types of models, through professional manufacturers to wholesale products, so that it can also ensure its quality.

With more and more varieties of power adapters, now more and more manufacturers, as long as the quality of the product is guaranteed, the working parameters and output joint and the original consistency, then different brands can be completely universal, but also for the working parameters are not strictly the same, can have a certain range of allowable changes. What are the main operating parameters of the power adapter? How to choose? First, the main working parameters of the power adapter: 1, input voltage and input current; 2, output current and output current; 3, output connection head (interface) and output polarity (basically different brands have their own standards); Generally, notebook adapters are 110-240V input, in line with global international standards. Two, the purchase of power adapter refer to the following principles: 1, the principle is to choose the same brand of the same type, if not, it can only find other brands; 2, the output voltage of the adapter is best equal to the voltage required by the notebook, if different, then as close as possible to the required voltage of the notebook, controlled within the error of ±5%, this is because the notebook inside the voltage regulator circuit generally has a margin design, in a certain range of input voltage changes, can work normally and stably; Beyond this range, the voltage is too low, the computer may not work steadily or even light up the machine; If the voltage is too high, it may burn out the voltage regulating circuit inside the computer. An Acer laptop, for example, requires a 15V, 3.36A input, but with an IBM16V, a 3.36A adapter will work perfectly with it. 3, the maximum output current of the adapter should be consistent with the maximum current required by the notebook as far as possible, if different, it should be equal to or greater than the required current of the notebook; Note: As long as the current is large, you don't have to worry about how big, no matter how big, don't be afraid, don't worry about burning the machine! But the current should not be too small, because the screen flashing and other unstable conditions may occur. For example, the IBMT30 adapter (16V, 4.5A), although it works safely with the IBMThinkPad 20(16V, 3.36A), it can also work with the ThinkPadX31(16V, 3.5A). The principle is: the power adapter is based on the load to adjust the output current, not static. Like the IBM16V, 4.5A adapter above, it can provide up to 4.5A operating current, but with the T20, it can only output up to 3.36A current. In fact, due to the different working conditions of the laptop, the current it needs is also in constant change, the adapter according to the working conditions of the notebook at any time to adjust the output power, to meet the needs of the computer. The adapter with a higher output current is more flexible, which is a bit of a "kill a chicken with a knife". However, the reverse is not good. Although the T20 adaptor can light up the T30, the T30 screen sometimes flickers because the T20 adaptor cannot provide the consistent operating current required by the T30. 4, the last point should have been in the first place, that is the adapter output interface and output polarity (pay attention to the positive and negative poles) problem, you have to ensure that the purchase of the adapter can be inserted into your laptop, otherwise even if the working parameters are exactly the same, but not plugged in, you have what use. Due to the independence of the major notebook manufacturers, the adapter adapters of different brands are different. The adapters of different series of notebook adapters of the same brand generally have the same specifications, but sometimes different brands may also use the same interface. For the power adapter main working parameters and selection principles are introduced here, I hope everyone can buy the right products!

Nowadays, every aspect of life and all walks of life can not be separated from the use of switching power adapter. With the rapid development of switching power supply, switching power supply has been widely used in human applications with the characteristics of high efficiency, small size and convenience. However, the structure of switching power supply is not so simple. It is still difficult for beginners to develop switching power supply. There are many types of components used in switching power supply. The following is an introduction to the functions of components designed for switching power supply. Switching power components are divided into you two classes, one is a general component, one is a special component! One. Resistor: 1. Sampling resistance - constitutes the output voltage of the sampling circuit, the sampling voltage to the feedback circuit. 2. Voltage balancing resistance - plays a voltage balancing role in the symmetrical DC input circuit of the switching power supply, also known as balance resistance. 3. Voltage divider - constitute resistance voltage divider. 4. Drain resistance - when the power can be electromagnetic interference (EMI) filter capacitor stored charge discharge. 5. Current limiting resistance - plays the role of current limiting protection, such as used as a voltage regulator, optical coupler and input filter capacitor current limiting resistance. 6. Current detection resistor - Used with overcurrent protection circuit to limit the output current limit of switching power supply. 7. Shunt resistor - provides a bypass for current. 8. Load resistance: Load resistance (including equivalent load resistance) of the switching power supply. 9. Minimum load resistance - Minimum load resistance required to maintain the normal operation of the switching power supply to prevent the output voltage from being too high due to the open load. 10. False load - temporary load (such as resistance wire, cement resistance) when testing the performance indicators of the switching power supply. 11. Filter resistance - Used as filter resistance in LC filter, RC filter, π filter. 12. Bias resistance - provides bias to the control end of the switching power supply, or used to stabilize the operating point of the transistor. 13. Protection resistance - often used in RC type absorption circuit or VD, R, C clamp protection circuit. 14. Frequency compensation resistors - such as RC-type frequency compensation networks that make up error amplifiers. 15. Damping resistance -- prevents resonance in the circuit. Two, inductor: 1. Filter inductance - constitute LC filter. 2. Energy storage inductor - often used in step-down or boost DC/DC converter circuit. 3. Oscillation inductance - constitute LC type oscillator. 4. Common-mode inductance, also known as common-mode choke, is often used in EMI filters to inhibit common-mode interference. 5. Series mode inductor - also known as series mode choke, it adopts single winding structure, generally in series in the input circuit of the switching power supply. 6. Frequency compensation inductance - constitute LC type, LCR type frequency compensation network.

1. Single end exciting type Single end: Drive the pulse transformer through a single switching device. Forward excitation: the phase relationship between the original and the paying side of the pulse transformer ensures that when the switch tube is on and the original side of the pulse transformer is driven, the paying side of the transformer supplies power to the load at the same time. The biggest problem of this circuit is that the switching tube T works alternately in the on/off state. When the switching tube is off, the pulse transformer is in the "no-load" state, in which the stored magnetic energy will be accumulated to the next cycle until the inductor is saturated, so that the switching device is burned. The magnetic flux reset circuit constituted by D3 and N3 in the figure provides a channel for releasing excess magnetic energy. 2, single end flyback Flyback circuit and forward circuit in contrast, the pulse transformer original/pay side phase relationship, to ensure that when the switch tube is on, driving the pulse transformer original side, the transformer pay side does not supply power to the load, that is, the original/pay side staggered off. It is easy to solve the problem of magnetic energy accumulation in the pulse transformer. However, due to leakage of the transformer, voltage spikes will be formed on the primary side, which may breakdown the switching device. Therefore, voltage clamp circuit needs to be set to protect the circuit composed of D3 and N3. From the schematic diagram of the circuit, flyback and forward are very similar, the surface is only the transformer with the same name of the difference, but the circuit is different, D3, N3 function is different. 3, push-pull (transformer center tap) type The characteristics of this circuit structure are: symmetrical structure, pulse transformer original side is two symmetric coil, two switch tube connected into a symmetric relationship, wheel flow is broken, the working process is similar to the linear amplifier circuit in class B push-pull power amplifier. Main advantages: high utilization rate of magnetic core of high-frequency transformer (compared with single-ended circuit), high utilization rate of power supply voltage (compared with the half-bridge circuit described later), large output power, low level of both tube bases, simple driving circuit. Main disadvantages: low utilization rate of transformer winding, high voltage requirement of switching tube (at least twice of the supply voltage). 4. Full bridge type This circuit structure is characterized by four identical switching tubes connected into a bridge structure to drive the original side of the pulse transformer. In the figure, T1 and T4 are a pair, driven by the same set of signals, and at the same time switch on/off terminal; T2 and T3 are another pair, driven by another set of signals, and turn on/off terminals at the same time. Two pairs of switching tubewheel flow/break, forming a positive/negative alternating pulse current in the primary side coil of the transformer. Main advantages: Compared with push-pull structure, the primary side winding is reduced by half, and the switching tube voltage is reduced by half. Main disadvantages: the number of switch tubes used is large, and the required parameter consistency is good, the drive circuit is complex, and it is difficult to achieve synchronization. This kind of circuit structure is usually used in the super large power switching power supply circuit above 1KW. 5. Half bridge type The structure of the circuit is similar to the full bridge type, but the two switch tubes (T3, T4) are replaced by two equivalent large capacitors C1 and C2. Main advantages: It has certain anti-unbalance ability, and the requirement of symmetry of the circuit is not very strict; Adaptable power range is large, from tens of watts to kilowatts can be; Low pressure requirement of switching tube; Circuit cost is lower than full bridge circuit. This circuit is often used in a variety of unregulated output DC converter, such as electronic fluorescent lamp drive circuit.

1. Know what you want. Under normal circumstances, we only think of buying switching power when the products we use fail. We can directly take the previous adapter to the corresponding store to buy. Basically selling electronic products or repair shops will have this kind of switching power supply, the price is about dozens of yuan to one hundred yuan, is not a very high price. And if you do not know what type of switching power supply you used before, then it is best to directly take their own use of products to the store to buy, try switching, switching power really meet our requirements after the purchase, so that you can avoid unnecessary trouble. 2. Choose the right brand. The brand of switching power supply is still more, and its service life is also relatively long, like the mobile phone power supply may be used several times a day, if its quality is not high, it is easy to have problems. I believe you are more willing to buy high-quality products, although the price of switching power supply on the market is about dozens of yuan, but because we want to compare the pros and cons of the product is still a certain difficulty, so we must choose brand products. The products of big brands or big manufacturers are tested by the authority department. The quality of their products is better. Although the unit price is slightly higher, there will not be much difference in price, which is more suitable for us to choose. 3. Determine after-sales service. Switching power supply can basically be used for a few years, of course, this is to buy the product is a regular product on the basis of the long service life can be guaranteed. However, when we buy such products, it is best to confirm the after-sales service with the merchants. If there is a problem within a month of use, the merchants should provide unconditional replacement of the new products or help us carry out maintenance. It is not recommended to choose non-brand three no products, this kind of product quality is likely to have problems, and may even threaten our safety, and can provide better after-sales service business products are more quality assurance. Personal purchase of switching power must choose professional products, brand products are about twice as expensive, but such products are more worthy of our trust, its use effect is better, but also more secure.

The power adapter is a tool used in many electrical appliances, but in recent years, it is not uncommon for the power adapter to cause fires. How to ensure the safety of the temperature of the power adapter? How to ensure the safety of the power adapter temperature? 1. Non-standard power plug We rule the household single-phase power supply plug pole ground and pole and ground two ways, the use of the power plug shown in should be able to avoid unipolar stabbing, when a latch plug socket live plug sleeve cooperation of other bolts is not accessible. Viewing found that the appearance of the latch is long, the latch is too long and the danger of electric shock is added in the cooperative process by the presence of the user. In addition, the shape of the power plug does not conform to the more common in our country use of plug socket demand is incomplete, it very simple leads to electric shock. 2. Commodity symbols are incomplete or non-standard Labels should include the correct installation, the correct guidance of the user's important information to indicate the commodity symbol, in order to ensure the user's personal and industrial safety of one of the fundamental ways. After use, eye-catching, identification requirements label should not fall, after normal use, should be cleaned and the content is clear. Goods for sale need a simplified Chinese symbol, which should contain less information such as manufacturer's or distributor's title, trademark or identification symbol, type code or standard type, power supply nature, additional power supply voltage size. If the information is incomplete and does not guide consumers to use it correctly, some will even misuse and endanger their cooperative electronic equipment, a question together, the symbol of our country, title or trademark, type code or type standard. 3. Heating under normal operating conditions does not meet the demand The role of the power adapter is to transform the voltage needs to consume some of the power, this is due to the loss of the voltage transformation process, by radiation, convection, conduction, three cooling mode of electric energy is converted into heat energy, some of the heat will be distributed to the surrounding environment, self-absorption of the other some of the heat, so the temperature of the power adapter rises. Heat insulation material method, the internal temperature of the equipment increases to a certain temperature will cause the rapid aging of the insulation material, shorten the life of the test, and then cause the function to decline safety. Such a power adapter, the normal operating temperature can only be controlled in a reasonable scale, in order to ensure its safety, ability to work normally. It is found that under normal operation conditions, the temperature of printed circuit boards and transformer windings of some commodities is too high, which poses great safety risks. As consumers, we should pay close attention to the temperature rise of the product. A simple way is to use the temperature rise of the test housing of the product. In the case of the power adapter, the temperature difference between the ambient temperatures does not exceed 60°C. We should stop using it in time. 4, in short circuit and overload safety function of dangerous goods Under the condition of short-circuit fault, the output short-circuit, capacitors or other diodes, the internal loss of the power adapter increases sharply, resulting in the rise of temperature in each. Electronic circuit design and use, should ensure that in abnormal operation and fault conditions, the temperature of the product can not exceed the requirements of the rules, and even can not make the surrounding items fire risk, power adapters may be damaged under the fault condition, but you can not reduce the function of the safety equipment. The key component of a power transformer is a safe barrier between the main circuit and the auxiliary circuit of the power adapter. Therefore, the transformer skeleton material and the thickness of the insulation layer have strict requirements to meet the needs of strengthening insulation between primary and secondary. The temperature rise of transformer winding of a single commodity is too high in the fault condition, resulting in bone ablation.

1, input low pressure point cycle test Test specification The setting back difference of the input undervoltage point protection of the primary power module usually occurs in the following situations: The input voltage is low and close to the undervoltage point of the primary power module. When the load is loaded, the voltage will rise after the load is removed due to the internal resistance of the power supply. As a result, the primary power module may be in the state of repeated development at low voltage. Test method The power module runs with full load, and the input voltage changes slowly from (input undervoltage point -3v) to (input undervoltage point +3v). The time is set to 5 ~ 8 minutes, and the power module runs repeatedly. The power module should work normally and stably. Decision criteria The primary power module runs normally and continuously, and the performance does not change significantly after at least 0.5 hours. Qualified; Otherwise, it is not qualified. 2, input transient high voltage test Test specification The pfc circuit uses the average value circuit for over and under voltage protection. Therefore, when the input transient high voltage, the pfc circuit may realize protection quickly and cause damage. Test the stable operation ability of the primary power module under the transient condition to evaluate the reliability. Test method a. For rated voltage input, use the dual-trace oscilloscope to test the input voltage waveform and the overvoltage protection signal, and the input voltage jumps from the power limit point to 300v by adding 5v. Read the 300v cycle number n before the overvoltage protection from the oscilloscope as the basis for the following tests. b. Rated input voltage: The power module runs with full load and superimpose 300v voltage jump on the input. The stacking period is (n-1), the stacking frequency is 1 time /30s, and the operation lasts for 3 hours. Decision criteria The primary power module can run stably under the above conditions without damage or other abnormal phenomena. Qualified. Otherwise, it is not qualified. 3, input voltage drop and output dynamic load Test specification When the input voltage drops during the actual use of the primary module, the limit condition of sudden load on the power module may occur. At this time, the power components and magnetic components work in the maximum transient current state. The test can verify the rationality of the control timing sequence, current limiting protection and other circuits and software design. Test method a. Adjust the input voltage to jump between undervoltage point +5v(duration: 5s) and overvoltage point -5v(duration: 5s); adjust the output voltage to jump between maximum load (maximum rated capacity, duration: 500ms) and no-load (duration: 500ms), and run for 1 hour; b. Adjust the input voltage to jump between undervoltage point +5v(duration: 5s) and overvoltage point -5v(duration: 5s). Adjust the output voltage to jump between maximum load (maximum rated capacity, duration: 1s) and no-load (duration: 500ms), and run for 1 hour. Decision criteria Under the above conditions, it should be able to operate stably, without damage or other abnormal phenomena, qualified; Otherwise, it is not qualified. If damage occurs, record the fault to provide a basis for analyzing the cause of damage.

1, repeated short-circuit test Test specification If the output of the module is shorted in various input and output states, the module should be able to realize protection or retraction. If the module is shorted repeatedly, it should automatically resume normal operation after the fault is removed. Test method A. No load to short circuit: within the full range of input voltage, switch the module from no load to short circuit. The module should be able to realize output current limiting or retraction normally. After the short circuit is removed, the module should be able to resume normal operation. Let the module repeatedly work from no-load to short circuit, short circuit time is 1s, release time is 1s, the duration is 2 hours. After this, short circuit release, judge whether the module can work normally. B. Full load to short circuit: in the full range of input voltage, the module from full load to short circuit, the module should be able to realize output current limiting or retraction normally, after the short circuit is removed, the module should be able to resume normal operation. Let the module go from full load to short circuit and then stay short for 2 hours. Then short circuit release, judge whether the module can work normally. c. Short-circuit startup: the output of the module is shorted first, then powered on, and then powered on within the input voltage range of the module. The module should be able to achieve normal current limiting or retraction, and after the short-circuit fault is removed, the module should be able to resume normal operation. Decision criteria After the above test, the power module can work normally after starting; Open the case to check that there is no abnormal phenomenon in the circuit board and other parts (such as whether the input relay is stuck in the process of short circuit, etc.), qualified; Otherwise, it is not qualified. 2, repeated switch machine test Test specification When the output power module has the maximum load, the input voltage is 220v (input overvoltage point -5 V) and (input undervoltage point +5v), the input is switched on and off repeatedly to test the performance of the power module on and off repeatedly. Test method a, the input voltage is 220v, the power module fast with the maximum load, use contactor to control the voltage input, close 15s, disconnect 5s(or can use ac source for simulation), continuous operation for 2 hours, the power module should be able to work normally; b. The input voltage is the overvoltage point -5v, and the power module has the maximum load. Use contactor to control the voltage input, and turn off for 15s (or you can use ac source to simulate). c, the input voltage is undervoltage point -5v, the power module has the maximum load, use contactor to control the voltage input, close 15s, disconnect 5s(or can use ac source to simulate), run continuously for 2 hours, the power module should be able to work normally. Decision criteria In the above test, the power module works normally. After the test, the power module can work normally with no obvious change in performance, qualified; Otherwise, it is not qualified.

Nowadays, many failures in electronic circuits are caused by the failure of switching power supply, and most of the common failures of switching power supply are caused by the damage of some spare parts. For example, the switching tube in the switching power supply, habitual damage, but the switching transformer, damage probability is very small! Basically be able to ignore. Therefore, switching power supply manufacturers share a summary of some easily damaged components in switching power supply, and what failure conditions occur after damage, and share with everyone. 1. Fuse tube Burn commercial insurance is mostly caused by the large current flow of the power supply circuit, in other words, the power circuit behind the short circuit fault, such as the switch tube, current limiting resistance, bridge pile burn short circuit fault, integrated ic damage, large filter capacitor damage these are caused by burn commercial insurance, the fault condition is no reflection of the power supply. (Warm reminder: if you change the fuse tube, do not need to connect the power supply detection, must find the fault or adopt certain countermeasures before connecting the power supply) 2, filter capacitor damage (300V capacitor) When the filter capacitor is powered off or the volume is reduced, it will lead to stuck or no response when starting. The damage of the filter capacitor is generally visible from the appearance of the capacitor pack. (Of course, you can't afford it.) 3. Output filter capacitor: The fault condition is similar to the bad filter capacitor. 4. Switch tube The first point said, after the switch is damaged, it will generally burn commercial insurance, current limiting resistance will also follow the damage, and in some cases even PWM integrated ic will also follow the burn (but this is rarely the case). Even though the fuse tube is burned, the fault situation is no doubt connected to the power supply. 5, voltage regulator diode. In the diode bearing the opposite direction of the voltage exceeds its tolerance of the regulator value, the regulator will reverse direction of thermal breakdown, but this kind of thermal breakdown can be repaired, that is, after the voltage value is reduced, the regulator will get rid of the thermal breakdown situation, equal to the lead. If it is a short circuit fault, then the regulator has already been damaged, and the current flow exceeds the voltage regulator to bear the current flow, which is a breakdown and cannot be repaired. 6. Lotus root and TL431 The damage of these two components will generally lead to unstable output voltage or no voltage output. How to check it has been introduced in professional detail in my previous article (the damage of sampling resistance will also lead to similar problems). 7. Starting resistor: The starting resistor is connected to the 300V switching power supply and the base of the switching tube. The damage of the starting resistor will lead to 300V, but there is no voltage output, and the whole equipment has no reaction. 8. Current limiting resistance: To put it bluntly, the resistor damage overcurrent protection circuit work, and starting resistor 300V no output voltage. 9, PWM control integrated ic: PWM damage will lead to 300V, but no output voltage will also repeatedly burn switch tube and commercial insurance, inspection can be hit to distinguish the merits of the ground resistance value, all normal ground resistance value apart from its foot, the other foot is often several hundred ohm.