Problems that are easily overlooked in assembling large LED screens


Assembling LED large screens is a problem that is easy to ignore. When many customers assemble LED large screens for the first time, they have no concept, and they don’t know much about material selection, technology, and connection methods. Therefore, some abnormalities of LED screens occur. As a senior person in the LED industry, we can give you some insights to avoid the waste of time and materials caused by some neglected problems of LED large screens. As an electronic product, LED large screens are understandable for some failures during normal use.

There are integrated circuits and chips on the LED screen, and the smoke and burnt phenomenon of the integrated circuit chip is a relatively common failure. What is the reason why the chip of the full-color LED large screen smokes and burns down? Let us explain in detail below. 1. The power supply voltage is too high: the rated operating voltage of the LED module is usually 4.5V-5V, the maximum limit operating voltage of the integrated chip on the module is generally not higher than 7V, and the maximum reverse voltage of the LED lamp beads is also 7V the following.

Therefore, the power supply voltage above 7V can damage the integrated chip and LED lamp. When the voltage reaches around 9V, conventional constant current/constant voltage driver chips tend to start to heat up rapidly and may smoke. Under normal circumstances, when the voltage is 10-11V, the chip will be burned to varying degrees if it is powered on for about 2 seconds.

Since the LED large screen is powered by a constant voltage switching power supply with an output voltage of 5V, the possibility of overvoltage is not very high. Even if the control circuit of the switching power supply fails, the possibility of its output voltage being abnormal and reaching more than 9V is very small (it does not mean that it is impossible!). It is worth mentioning that for some low-quality switching power supplies, even if the high output voltage ripple cannot cause the chip to smoke and burn, it is still enough to cause the chip to fail.

2. Abnormal control signal: It is also very common for a full-color LED large screen to have a row of constant and bright faults, which are often caused by abnormal contact of the cable or errors in debugging parameters. Strictly speaking, a well-designed LED large screen product should have a protection circuit to prevent the line from being bright and always on. For products without a protection circuit, if the line is bright and steady, if it is not eliminated in time, the temperature of the line driver chip (such as 4953) of the module may rise sharply due to continuous high-current operation and eventually burn out.

Of course, compared with previous products, the current full-color LED large-screen modules in the industry, the load power consumption of the row driver chip is relatively low (less than 2A), and the maximum operating current of most row driver chips is around 3A. It is less likely that the row driver chip will be smoked and burned because the row is always on. Therefore, most products on the market are no longer designed with protection circuits. 3. The positive and negative poles of the power supply are reversed: for electronic products designed according to the specifications, the positions of the power terminals will have"VCC"and"GND"ID (or"+","-"), indicating the wiring positions of the positive and negative poles, respectively.

However, for operators who lack the basic knowledge of electrical and electronics, it is still possible to reverse the positive and negative poles of the power supply unconsciously, and even qualified technicians may make operational mistakes. Reverse connection of the positive and negative poles of the power supply will often cause most of the constant current/constant voltage driver chips on the module to smoke and burn. Summary: In practical applications, most of the causes of chip smoking and burning are reversed positive and negative poles, followed by abnormal control signals, but this situation will become increasingly rare, and finally a very small number of power supply overvoltage conditions.

Some of these faults are caused by humans. Whether it is an LED large screen manufacturer or an end user, in order to reduce the occurrence of full-color LED large screen chip failures, it is very necessary to improve the technical level of operators. .

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