Testing of fixed capacitors

    a. Detecting small capacitors below 10pF
    The capacity of fixed capacitors below 10pF is too small. Using the multimeter E-TDA7386 to measure can only check whether it has leakage, internal short circuit or breakdown. When measuring, use the multimeter R×10k block, as shown in Figure 3-18. Use two test leads to connect the two pins of the capacitor at random, and the resistance should be infinite.
    If the measured resistance (pointer swings to the right) is zero, it means that the capacitor is leaking or damaged or has internal breakdown.

    b. To check whether the 10pF-0.01F fixed capacitor
    is charged, the quality of the capacitor should be determined. The multimeter is set to R×lok position, and the test circuit is shown in Figure 3-19. Since the composite triode composed of VT1 and VT2 has an amplifying effect, the charging and discharging process of the capacitor under test can be amplified, so that the swing amplitude of the multimeter pointer is increased, which makes it easier to observe the swing amplitude of the pointer, thereby confirming whether the fixed capacitor is charged well. The test process is shown in Figure 3-20.

Figure 3-19 Capacitor test circuit

    When testing a capacitor with a small capacitance, you need to repeatedly switch the capacitor pins to clearly see the swing of the multimeter pointer.