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例1:三星DVC-650。 故障现象;无论是VCD及CD碟片均不能播放,显示屏显示“NO DISC”。 分析与检修:先打开机器上盖,通电后发现激光头聚焦,寻迹动作正常,但仔细观察激光头无激光射出,因此估计激光二极管可能损坏,再用万用表测量激光二极管的正反向电阻值,结果为:正向电阻14kΩ正常,反向电阻值为无穷大,说明二极管没有损坏,继续测量驱动三极管VQ_2,发现该管c极在光头聚焦时只有0.6V,且毫无变化,于是拆下VQ检测,该管e极断路,换新管后,机器恢复正常。
Example 1: Samsung DVC-650. Symptoms; neither VCD nor CD disc can play, the display shows “NO DISC”. Analysis and Overhaul: First open the machine cover, power and found the laser head focus, tracing normal, but careful observation of the laser head laser emission, it is estimated that the laser diode may be damaged, and then use a multimeter to measure the positive and negative resistance of the laser diode , The result is: forward resistance of 14kΩ normal, the reverse resistance is infinite, indicating that the diode is not damaged, continue to measure the drive transistor VQ_2 and found that the tube c-pole in the optical head focusing only 0.6V, and no change, then remove the VQ Detection, the tube e pole circuit, after the new tube, the machine returned to normal.