source:Other information release time:2023-04-19 Hits: Popular:PCB Assembly company
1. It is strictly forbidden to use the ground -to -ground testing equipment without an isolated transformer to contact the TV, audio, video and other equipment to detect the PCB board
It is strictly forbidden to use the instrument equipment that has been grounded to directly test the TV, audio, video and other equipment without power isolation transformers. Although the general conclusion machine has a power transformer, when it comes to contact with a special TV or audio equipment that is more special, especially the larger output power or the nature of the power supply. Television, audio and other equipment with the bottom plate causes short circuits of power supply, which affects integrated circuits, and further expands the fault.
2. Pay attention to the insulation performance of the electric soldering iron for detecting the PCB board
The use of soldering iron welding is not allowed to be used to confirm that the soldering iron is not charged. It is best to ground the shell of the soldering iron. It should be more careful about the MOS circuit. It can be safer to use a low -voltage circuit iron of 6-8V.
3. To understand the working principle of integrated circuits and its related circuits before detecting the PCB board
Before checking and repairing integrated circuits, you must first be familiar with the functions of the integrated circuit used, internal circuits, main electrical parameters, the role of each pin, and the normal voltage of the pins, waveforms, and peripheral components. If you have the above conditions, analysis and inspection will be much easier.
4. Test the PCB board and do not cause short circuit between pins
When the voltage measurement or testing waveform with a oscilloscope probe, the surface pen or probe should not be short circuit between the pins of the integrated circuit due to sliding. It is best to measure on the peripheral printing circuit directly connected to the pin. Any short circuit at any moment is easy to damage the integrated circuit. When testing the CMOS integrated circuit that is packaged flat -type packaging, be more careful.
5. Detect the internal resistance of the PCB board test instrument.
When measuring the DC voltage of the pins of the integrated circuit, a universal meter with an internal resistance of the header should be greater than 20kΩ/V, otherwise there will be a large measurement error on certain pins voltage.
6. Pay attention to the power integration circuit of the PCB board
The power integrated circuit should be well dissipated, and it is not allowed to work in a high power state without a heat sink.
7. Detecting the pcb board quotation is reasonable
If you need to add peripheral components instead of the damaged part inside the integrated circuit, a small component should be selected, and the wiring should be reasonable to avoid unnecessary parasitic coupling, especially to handle the grounding between the audio function and the front amplifier circuit. end.
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