Fault judgment and detection method of circuit board components

Date：2022-02-23 16:35:42Views：1176

The core of electronic equipment is the circuit board, which is welded and assembled by various types of electronic components. If the equipment fails or has a short circuit, most of the reasons will be caused by the failure or damage of electronic components. Next, the third-party testing organization will introduce you to the fault judgment and testing methods of circuit board components. You may wish to continue reading.

1. Measure the polarity of each pin of rectifier bridge

Multimeter setting R × 1K gear, the black lead is connected to any pin of the bridge pile, and the red lead successively measures the other three pins. If the readings are infinite, the black lead is connected to the output positive pole of the bridge pile. If the readings are 4 ~ 10K Ω, the pin connected to the black lead is the output negative pole of the bridge pile, and the other two pins are the AC input end of the bridge pile.

2. Judge the quality of crystal oscillator

First use a multimeter (R × 10K block) measure the resistance value at both ends of the crystal oscillator. If the resistance value is infinite, it indicates that the crystal oscillator has no short circuit or leakage; Then insert the test pen into the power test socket, hold any pin of the crystal oscillator with your fingers, and touch the other pin with the metal part at the top of the test pen. If the neon bubble of the test pen is red, it indicates that the crystal oscillator is good; If the neon bubble is not bright, the crystal oscillator is damaged.

3. Unidirectional thyristor detection

R of available multimeter × 1K or R × Measure the forward and reverse resistance between any two poles at gear 100. If the resistance of a pair of poles is found to be low (100 Ω ~ LK Ω), then the black probe is connected to the control pole, the red probe is connected to the cathode and the other pole is the anode. The thyristor has three PN junctions. We can judge whether it is good or bad by measuring the forward and reverse resistance of PN junction. When measuring the resistance between control electrode (g) and cathode [C), if the forward and reverse resistance are zero or infinite, it indicates that the control electrode is short circuited or open circuit; when measuring the resistance between control electrode (g) and anode (a), the forward and reverse resistance readings should be large; when measuring the resistance between anode (a) and cathode (c), the forward and reverse resistance should be large.

4. Polarity identification of bidirectional thyristor

The bidirectional thyristor has main electrode 1, main electrode 2 and control electrode. If a multimeter R is used × 1K gear measures the resistance between two main electrodes, and the reading should be approximately infinite, while the forward and reverse resistance readings between the control electrode and any main electrode are only tens of ohms. According to this characteristic, we can easily identify the control electrode of the bidirectional thyristor by measuring the resistance between the electrodes. When the black probe is connected to the main electrode 1. When the red probe is connected to the control electrode, the measured forward resistance is always smaller than the reverse resistance. Therefore, it is easy to identify the main electrode 1 and main electrode 2 by measuring the resistance.

5. Check the quality of LED

Set the multimeter to r first × 10K or R × L00k block, and then connect the red probe with the "ground" leading out end of the nixie tube (taking the common cathode nixie tube as an example), and the black probe is connected with other leading out ends of the nixie tube in turn. The seven sections should emit light respectively, otherwise it indicates that the nixie tube is damaged.

The above is all about the fault judgment and detection methods of circuit board components. I hope you can help. Components are used in a wide range of fields, such as industrial frequency converter, servo and industrial electronic equipment. The medical industry is a big demand industry. Mobile phones, computers and many other electronic products around people's lives. The development of modern science and technology almost needs hardware equipment to meet the needs.