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What Is A Crystal? And How To Test It


Crystal are use to keep the frequency of the clock from drifting. If the signal from this clock stops, or is weak, or the pulses begin to vary, the electronic equipments might show intermittent faults or might stop altogether. The microprocessor pins that hold the crystal are usually called OSC IN and OSC OUT as shown in Figure 1 and the frequency is marked on the crystal. Typical examples of crystal oscillator frequency are 3.58MHZ, 4MHZ, 8MHZ, 24MHZ etc.

Testing Crystal
Crystals are quite fragile components because of their construction. Unlike a resistor or capacitor, if you drop one on the ground from a decent height, its 50-50 bet whether it will work again. Testing the crystal is not a breeze either. You cannot just take out your trusty multimeter and plug the crystal in it. In fact, there are three right ways to test a crystal: -

(a) Using Oscilloscope
A crystal produces a sine wave when excited. It is appropriate then, to see a waveform representative of a sine wave on the clock pins. If the clock is not functioning properly, replace the crystal. In most cases this should solve the problem since microprocessors are usually very reliable. Check the crystal with power on.

(b) Frequency Counter
Frequency Counter can be use to check the frequency of the crystal. The reading must be taken when the equipment power is switch "on". Place the probe of frequency counter to the crystal pin and read the measurement. Be sure that your frequency counter meter has the range that is higher than the crystal frequency you are measuring.

(c) Crystal Checker
With this method, usually the crystal is placed in the feedback network of a transistor oscillator. If it oscillates and the LED is lighten up, this mean that the crystal is working. If the crystal doesn't work, the LED stays off. Instead of using LED, some other crystal checker uses a panel meter to indicate if the crystal is working or not.

Jestine Yong is a electronic repairer and writer. For more information about electronic repair please visit his website at http://www.noahtec.com







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