Fixed capacitor inspection

A Detecting small capacitors below 10pF Because the fixed capacitor capacity below 10pF is too small, use a multimeter to measure, and only qualitatively check for leakage, internal short circuit or breakdown. When measuring, you can use the multimeter R × 10k block, use two meter pens to connect the two pins of the capacitor, the resistance should be infinity. If the measured resistance value (the pointer swings to the right) is zero, the capacitor leakage is damaged or internal breakdown.

B Check if the 10PF~0 01μF fixed capacitor has a charging phenomenon, and then judge whether it is good or bad. The multimeter uses R × 1k block. The beta values ​​of the two triodes are all above 100, and the penetration current may be selected by a combination of 3DG6 and other types of silicon triodes. The red and black test leads of the multimeter are respectively connected to the emitter e and the collector c of the composite tube. Due to the amplification effect of the composite triode, the charging and discharging process of the measured capacitor is amplified, so that the multimeter pointer swing amplitude is increased, thereby facilitating observation. It should be noted that during the test operation, especially when measuring the capacitance of a small capacity, it is necessary to repeatedly exchange the two points of the measured capacitor pins to contact A and B to clearly see the swing of the multimeter pointer.

C For a fixed capacitance of 0 01μF or more, use the R × 10k block of the multimeter to directly test whether the capacitor has a charging process and whether there is an internal short circuit or leakage, and estimate the capacity of the capacitor according to the amplitude of the pointer swinging to the right.