The flow of charged particles through wires is known as electricity. The constant flow of electricity through circuits can be desirable for appliances that need constant power. However sometimes it is necessary to produce electrical signals that change with time, in order to produce timing circuits. A crystal oscillator is a simple electrical component that has an oscillatory dependence of voltage with time. The devices are used in various applications including timing circuits within computers. A crystal oscillator can be tested using a digital multimeter.
Locate the position of the crystal oscillator. If the crystal oscillator is within an electrical circuit, it needs to be located. If it is connected to a computer motherboard, the crystal oscillator will normally be labelled "XTAL", and the frequency of oscillation will be written on top of the device.
Plug the measurement probes into the multimeter. The red probe should be plugged into the positive terminal and the black probe should be plugged into the negative terminal. Switch on the multimeter and select the frequency function.
Switch on the device which powers the crystal monitor. The test will only work when the crystal monitor is powered. Bring the measurement probes of the multimeter into contact with the metallic legs of the crystal oscillator. One probe should touch each leg. The multimeter should now read a frequency that corresponds to the one written on the crystal oscillator casing. If no oscillation frequency is measured, it is fluctuating strongly with time, or it is at a different to the stated value, then the crystal oscillator is likely to be faulty.