First, LED display maintenance testing methods
1, short circuit detection method, the multimeter to short-circuit detection block (usually has an alarm function, such as conduction will be issued a chirp), the detection of whether there is a short circuit phenomenon, found that short-circuit should be resolved immediately, short-circuit phenomenon is the most common LED Display module failure. Some can be found by looking at the IC pin and the pin header. Short-circuit detection should be performed with the circuit powered down to avoid damage to the multimeter. This method is the most commonly used method, simple and efficient. 90% of the faults can be detected by this method.
2. Resistance detection method: Adjust the multimeter to the resistance file, detect the resistance value of a certain point of a normal circuit board to the ground, and then test whether the resistance of the same point of another circuit board is different from the normal resistance value. If it is different then the scope of the problem is determined.
3, voltage detection method, the multimeter to the voltage file, to detect a problem in the circuit of a point of the voltage to the ground, whether compared with the normal value, you can easily determine the scope of the problem.
4, pressure drop detection method, the multimeter to the diode drop detection file, because all of the IC is composed of many basic units, but miniaturized, so when there is a current through a pin, There will be a voltage drop on the pin. Generally, the voltage drop on the same pin of the same type of IC is similar, and the voltage drop on the pin is better or worse, and the circuit must be operated under the condition of power off.
Second, LED display maintenance necessary tools
1、1 soldering iron and 1 sniffer, some solder
One or two 5V power supply, powering the receiving card and maintenance module or unit board
3、One electric batch for quick disassembly of module or cell board
4, computer + send card, used to send the program to the receiving card
5, receiving card + HUB board, used to observe the module or unit board failure phenomenon
6, a multimeter, used to detect the specific failure of the module or unit board
7. One each for rake, scissors and pliers
Third, the basic steps of LED display maintenance
1, determine the type of HUB board used by the module or unit board, so that the cable interface definition can be the same
2. According to different models of modules or cell boards, send the corresponding program to the receiving card to ensure that the module and the cell board are displayed under the correct program. This is the premise to find the cause of the fault. The model of the module or cell board is printed on the general PCB board.
3. Observe the phenomenon of module or cell board to determine the initial failure. For example, common Xenon lamps, strings, small boxes, etc.
4, using a multimeter to identify the fault, mainly using the above short-circuit detection method to detect between the chip and the lamp foot.
5. Test again.