In today's electronic technology era, we are inseparable from the smart products in our lives, especially mobile phones. In this fast-paced city of mobile payment, if we leave the mobile phone for one minute, I am afraid that there will be a lot of inconvenience. The mobile phone relies on it. A crystal oscillator smaller than a grain of rice determines the "life and death" of the entire circuit board. If it doesn't work, the entire system will be paralyzed, and people in the industry can be compared to the heart of the circuit board. So how to judge the quality of the crystal oscillator? Here is a brief introduction:
1. Appearance marking inspection
(1) Observation of the appearance of the crystal oscillator: from the case to the base and the leads, if possible, you can use a magnifying glass to inspect, check from different angles in different directions, whether the brightness is fuzzy, whether the case is clean, etc. The appearance of the new crystal is basic There are no obvious fingerprints and other incidental debris, and the pressure-sealed bonding part between the shell and the base is neat and not prominent and flawless.
(2) Observation of printing logo: The crystal oscillator produced by the original factory, the front of the shell will not enter the next process until the crystal oscillator has passed the inspection. Laser printing, the printing is done by laser printing, all after the laser machine debugging Printing, from the strength and angle of the laser, has strict specifications. The overall ratio of the printing size is appropriate, clear and tidy, and it looks very comfortable, highlighting the crystal oscillator manufacturer's logo.
(3) Packaging style: The crystal oscillators shipped from the original factory are all packaged according to the unified requirements. The packaging style is clean and generous. The outer box has a product label with the company trademark or company name. The package label contains the product model, specification and size. , Precision requirements, resistance, quantity, QC test confirmation, production date and other main crystal parameter information, which is convenient for customers to check warehousing, production, and verification. It is also an important part of the traceability of product production.
2. Use a multimeter (R×10k block) to measure the resistance value at both ends of the crystal oscillator. If it is infinite, it means that the crystal oscillator has no short circuit or leakage; then insert the test pencil into the mains socket, and pinch any pin of the crystal oscillator with your fingers. Touch the other pin to the metal part at the top of the test pencil. If the neon bulb of the test pencil turns red, it means the crystal oscillator is good; if the neon bulb does not light up, it means the crystal oscillator is damaged.
3. Test the output pin voltage. Normally, it is about half of the power supply voltage. Because the output is a sine wave (peak-to-peak value is close to the source voltage), when tested with a multimeter, it is almost half.
4. Use a digital capacitance meter (or the capacitance file of a digital multimeter) to measure its capacitance. Generally, the capacity of the damaged crystal is significantly reduced (different crystals have a certain range of normal capacity)
5. Close to the ear and shake gently, it must be bad if there is a sound (the internal crystal has been broken, and the frequency will change if it can be used)
6. Use substitution method or oscilloscope to measure.
The above is the method to check the quality of the crystal oscillator. There is also a small trick, which is to connect a 1.5V battery to the two ends of the crystal oscillator, put the crystal oscillator to your ear and listen carefully. When you hear a click, it means that It's vibrating, it's good.
Summarized by Easybom.
