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Sep 17,2021| LED Knowledge
LED display has become one of the most important display devices in modern times, and it plays a very important role in the display field. When the full-color LED display fails, how should we deal with it? Here to share with you what are the methods in the process of overhauling the full-color LED display, I hope it will be helpful to you.
Through naked eye observation, open circuit is one of the problems often found in observation methods. It can be seen by eyes. For example, the PCB circuit is broken due to scratching, or the open circuit is caused by accidental breaking of an electric drill.
We can't tell whether the IC is burnt out with the naked eye, and we can replace it with a good IC; if the signal does not remember whether it was originally connected, we can use the unit board to measure the corresponding position to judge. The contrast method is often used in the process of overhaul. It is very important to master this method. It allows you to quickly find out where the fault is.
A failure of the full-color LED display may be caused by a variety of reasons. We need to accurately determine each cause of the display failure, and then deal with it one by one, but it must be noted that it must be processed according to the priority level.
Resistance detection method
Adjust the multimeter to the resistance position, check the resistance value of a certain point of a normal circuit board to ground, and then check the same point of another same circuit board to test whether the resistance value is different from the normal resistance value, if it is different, it is determined The scope of the problem.
Voltage detection method
Adjust the multimeter to the voltage range, check the ground voltage at a certain point of the circuit suspected to be problematic, and compare whether it is similar to the normal value, otherwise the fault range of the display screen problem will be determined.
Short circuit detection method
Set the multimeter to the short-circuit detection block to detect whether there is a short-circuit phenomenon in the LED display. After a short-circuit is found, it must be solved first to ensure that other devices are not burned out. Note: The short-circuit detection method must be operated when the circuit is powered off to avoid damage to the meter.
Pressure drop detection method
Adjust the multimeter to the diode voltage drop detection gear, because all ICs are composed of many basic single components, but are miniaturized, so when there is a current passing through one of its pins, there will be a voltage on the pin. drop. Generally, the voltage drop on the same pin of the same type of IC is similar, and it is better or worse according to the voltage drop value on the pin. Note: The voltage drop detection method must be operated when the circuit is powered off. This method has certain limitations. For example, if the tested device is high-impedance, it cannot be detected.
There are three main reasons for LED display failures: open circuit, short circuit, and IC damage. If it is an open circuit, it can be solved by connecting the signal interrupted line; if it is a short circuit, we only need to deal with the short circuit; the last problem is that the IC is damaged, just replace it with a new one.