Special attention is detected when detecting the quartz chips .

1 ) In the case of air conditioners board is powered with a multimeter to measure the quartz crystal oscillator input pin , there will be 2 ~ 3V dc voltage , the absence of such a voltage is generally crystal damage.

2 ) Use a multimeter to measure electrical barrier resistance values ​​crystal legs , normal resistance value should be infinite , otherwise described crystal damage.

3 ) If the conditions used to measure crystal oscilloscope input, output waveform , if any waveform , indicating crystal normal ; otherwise crystal damage.