How many do you know about the 9 small knowledge of PCB board proofing? The following knowledge is included in detail, and you can learn about it with PCB board proofing manufacturers in detail.
1. Pay attention to the insulation function of the electric soldering iron when testing the PCB board
It is not allowed to use a soldering iron to weld with electricity. It must be admitted that the soldering iron is not charged, and the shell of the soldering iron should be grounded. Be careful with the MOS circuit. It is safer to use a low-voltage circuit iron of 6~8V.
2. Before testing the PCB board, you must understand the working principle of the integrated circuit and its related circuits. Before checking and repairing the integrated circuit, you must first understand the function, internal circuit, main electrical parameters, function of each pin, and the normal voltage of the pin. The working principle of a circuit composed of waveforms and peripheral components. If the above conditions are met, the analysis and inspection will be much simpler.
3. It is strictly forbidden to use grounded test equipment to touch the live TV, audio, video and other equipment on the bottom plate to test the PCB board without an isolation transformer. It is strictly forbidden to directly test the TV, Audio and video equipment. Although general tape recorders have power transformers, when you come into contact with special TVs or audio equipment, especially those with large output power or do not know the nature of the select power supply, you must first clarify whether the chassis of the recorder is charged, otherwise it is very easy to contact with it. The TV, audio and other equipment with electricity on the bottom board cause a short circuit of the power supply, involving integrated circuits, causing further expansion of the fault.
4. The internal resistance of the PCB board test instrument should be large
When measuring the DC voltage of the pins of an integrated circuit, a multimeter with an internal resistance of the meter head greater than 20KO/V should be used, otherwise there will be a large measurement error for some pin voltages.
5. Pay attention to the heat dissipation of the power integrated circuit when testing the PCB board. The power integrated circuit should have good heat dissipation, and it is not allowed to work under high power without a radiator.
6. Check the PCB board to ensure the welding quality. The welding is indeed firm during welding, and the accumulation of solder and pores are easy to cause false welding. The welding time generally does not exceed 3 seconds, and the power of the soldering iron should be about 25W with internal heating. The integrated circuit that has been soldered should be carefully inspected, use an ohmmeter to measure whether there is a short circuit between the pins, and confirm that there is no solder adhesion before turning on the power.
