Detection methods and steps for LED display maintenance

　　1. Detection method for LED display maintenance

　　1. Short circuit detection method: adjust the multimeter to the short circuit detection position (usually with an alarm function, such as a beep if it is connected), and detect whether there is a short circuit. If a short circuit is found, it should be solved immediately. Short circuit is also the most common LED display module failure. Some can be found by observing the IC pins and the pin header pins. Short circuit detection should be performed when the circuit is powered off to avoid damaging the multimeter. This method is the most commonly used method, simple and efficient. 90% of the faults can be detected and judged by this method.

　　2. Resistance detection method: adjust the multimeter to the resistance range, detect the resistance value to ground of a certain point on a normal circuit board, and then test the same point on another identical circuit board to see if the resistance value is different from the normal one. If they are different, the scope of the problem is determined.

　　3. Voltage detection method: adjust the multimeter to the voltage range, detect the voltage to ground at a certain point in the circuit suspected of having problems, and compare whether it is similar to the normal value. This can easily determine the scope of the problem.

　　4. Voltage drop detection method: Set the multimeter to the diode voltage drop detection mode. Because all ICs are composed of many basic units, but they are miniaturized, when current passes through a certain pin, there will be a voltage drop on the pin. Generally, the voltage drop on the same pin of the same model of IC is similar. The voltage drop value on the pin is compared, and the operation must be performed when the circuit is powered off.

　　2. Essential tools for LED display maintenance

　　1. Electric soldering iron + suction gun 1 each, some solder

　　2. A 5V regulated power supply to power the receiving card and the module or unit board to be repaired

　　3. 1 electric screwdriver, used for quick disassembly of modules or unit boards

　　4. Computer + sending card, used to send program to receiving card

　　5. Receiving card + HUB board, used to observe module or unit board failure phenomena

　　6. A multimeter to detect specific faults of the module or unit board

　　7. 1 pair of tweezers, scissors, and pliers

　　3. Basic steps for LED display maintenance

　　1. Determine the type of HUB board used by the module or unit board so that the interface definition of the cable can be the same

　　2. According to different models of modules or unit boards, send the corresponding program to the receiving card to ensure that the module and unit board are displayed under the correct program. This is the premise for finding the cause of the fault. Generally, the model of the module or unit board will be printed on the PCB board.

　　3. Observe the module or unit board phenomenon and determine the preliminary fault, such as common blind lights, string points, small squares, etc.

　　4. Use a multimeter to find the fault, mainly by using the short-circuit detection method mentioned above to detect between the chip and the lamp pin.

　　5. Retest