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三、检修实例例1 机型:长城画龙G8253MF彩电故障现象:电源指示灯亮,但不能开机,有时伴音有“咕咕”叫声。分析与检修:直观检查未见异常。测300V端对地和输出端对地电阻均无明显短路现象。接上假负载通电检测,发现D904输出电压为35V,D907输出为3.2V,CPU(IC601)供电(52)脚为1.8V。有电压输出,说明电源已起振,输出电压偏低,故障点主要在稳压和开/关机控制电路。测开/关机控制电路Q903b极为0V,测D906反偏而截止,说明开关机电路无故障,且处于开
Third, overhaul Example Example 1 Model: Great Wall painting Dragon G8253MF TV Fault phenomenon: power indicator light, but can not boot, sometimes accompanied by “Cuckoo” cry. Analysis and Maintenance: No abnormal visual inspection. Measured 300V end to ground and output resistance to ground no significant short-circuit phenomenon. Connected to the false load power detection and found D904 output voltage of 35V, D907 output of 3.2V, CPU (IC601) power supply (52) pin 1.8V. A voltage output, indicating that the power supply has started, the output voltage is low, the main point of failure in the regulator and on / off control circuit. Test on / off control circuit Q903b very 0V, measuring D906 reverse bias and cut-off, indicating that the switch circuit is faultless, and in the open