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例1 机型:夏普C-3700DR型彩电故障现象:开机后无光无声,有“吱吱”声。分析与检修:由于开机后听到“吱吱”声,说明电源已经振荡,测量C_(635)两端电压,通电后电压升到115V后又降回30V左右。为区分是开关电源部分还是负载问题,断开负载(印制板上119跳线),然后在C_(635)两端并按一只60W的灯泡,开机后测C_(635)两端电压为70V稳定电压,灯泡发亮,说明故障部位为行负载部分。为区别是行输出级还是振荡级,测负载电流为40mA,说明故障部位不是输出级。在IC_(501)IX0065CE⑥脚加12V电源,测行振荡⑿脚无振荡波形,检查外围元件,
Example 1 Model: Sharp C-3700DR-type TV Fault phenomenon: boot soundless, “creak” sound. Analysis and Maintenance: As the boot heard “creak” sound, indicating that the power supply has oscillated to measure the voltage across C_ (635), after the voltage rose to 115V and then dropped back to about 30V. In order to distinguish whether it is part of switching power supply or load, disconnect the load (jumper 119 on the PCB), and then press a 60W bulb at both ends of C_ (635) and measure the voltage across C_ (635) 70V stable voltage, light bulb, indicating the fault part of the line load part. The difference is the line output level or oscillation level, the load current is 40mA, indicating that the fault is not the output stage. In the IC_ (501) IX0065CE ⑥ feet plus 12V power supply, the measured line oscillation ⑿ pin no oscillation waveform, check the external components,