实例9 机型:长城JTC471—2F彩电故障现象:开机通电无光栅、无图像,但调节音量电位器时喇叭内噪声发生相应变化。分析与检修:出现无光无图现象,故障部位一般在开关电源或行扫描电路。由于喇叭噪声随音量电位器旋动而发生相应变化,估计开关电源可能正常,因为伴 Example 9 Model: Great Wall JTC471-2F color TV Fault phenomenon: power on no grating, no image, but adjust the volume potentiometer when the speaker noise changes accordingly. Analysis and overhaul: there is no light without map phenomenon, the fault location is generally in the switching power supply or line scan circuit. As the speaker noise with the volume potentiometer rotation corresponding changes occur, it is estimated that the switching power supply may be normal, because with