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1.STAR(星)牌TCH-8520型20英寸彩电,开始工作时一切正常,过一段时间后出现“吱吱”响声,随着开机时间的延长,响声逐渐增强,但伴音、图象、色彩均正常。根据现象估计可能是行输出及显象管电路有软故障,随着开机时间的延长。使行输出变压器T_(444)负载加重。但是经检查行输出管Q_(404)及行输出变压器T_(444)温升均正常,查行输出电路及显象管电路的元器件也都没有问题,又考虑是否因其他部分元器件不好使电源负载增加而使开关变压器T_(801)磁芯抖动发出声响,查电源开关集成电路Q_(801)及开关变压器T_(801)温升也正常。由此可基本排除电路上的故障。又考虑
1.STAR (Tstar) brand TCH-8520 20-inch color TV, everything started to work properly, after a period of time, “creak” sound, with the boot time, the sound gradually increased, but the sound, image, color All normal. According to the phenomenon may be estimated line output and CRT circuit has a soft fault, with the extension of the boot time. Make the line output transformer T_ (444) load heavier. However, the output of the inspection line Q_ (404) and the line output transformer T_ (444) temperature rise are normal, check the line output circuit and the picture tube circuit components are also no problem, but also consider whether other parts of the bad So that the increase of power supply load makes the switching transformer T_ (801) core jitter sound, check the power switch IC Q_ (801) and the switching transformer T_ (801) temperature rise is also normal. This can basically rule out the circuit fault. Consider again