The PCBA Manufacture repairs PCB boards,The first step is to observe whether the circuit board has been damaged by humans. This is mainly from the following aspects:
1 See if the board is dropped, causing the board corner to be deformed, or the chip on the board being broken or broken. 2 Observe the socket of the chip to see if it is forced to be damaged because there is no special tool.
3 Observe the chip on the circuit board. If it is with a socket, first observe whether the chip is inserted incorrectly. This is mainly to prevent the operator from inserting the wrong position or direction of the chip when repairing the circuit board. If the error is not corrected in time, when the board is energized, the chip may be burned out, causing unnecessary losses.
4 If there is a shorting terminal on the board, observe if the shorting terminal is inserted incorrectly.
The maintenance of the circuit board requires a solid foundation in theory, careful work, and careful observation by the maintainer, sometimes at this step can determine the cause of the problem. The second step is to observe whether the components on the board are burned out. For example, resistors, capacitors, and diodes are not black or smeared. Under normal circumstances, even if the resistance is burnt, its resistance will not change, the performance will not change, and it will not affect the normal use. In this case, a multimeter is needed to assist the measurement. However, if the capacitors and diodes are burnt, their performance will change, and they will not play their due role in the circuit, which will affect the normal operation of the entire circuit. At this time, new components must be replaced. The third step is to observe the integrated circuit on the circuit board, such as 74 series, CPU, coprocessor, AD and other chips, there are no drums, cracks, burnt, black. If this happens, it is basically OK that the chip has been burned out and must be replaced. The fourth step is to observe whether the traces on the circuit board are peeled or burned. The copper hole is not separated from the pad. Step 5: Observe the fuses on the board (including the fuse and the thermistor) to see if the fuse is blown. Sometimes the fuse is too thin and can’t be seen clearly. You can use the auxiliary tool-multimeter to judge whether the fuse is damaged.
The above four cases are the method for the circuit board factory to repair the PCB board, which is basically due to the consequences of excessive current in the circuit. However, the specific cause of the current is too large, it is necessary to analyze the specific problem. But the general idea of finding the problem is to first carefully analyze the schematic diagram of the board, and then find out its superior circuit according to the circuit where the burnt component is located, and derive it step by step, and then rely on some experience accumulated in the work to analyze the easiest. Where the problem occurred, find out the cause of the failure.