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读2000年第6期许建荣的文章《HFC—2175彩电7812稳压块不佳为何屡烧TDA3653B?》,觉得该文确实提出了福日牌HFC—2175机型的一个通病,但对故障现象的描述和对故障根源的探讨都不太准确,特提出自己的见解,供许建荣及维修同行参考。本人曾检修多台同类故障的HFC—2175型机,发现屡烧TDA3653B的故障根源,其实不是“7812稳压块不佳”,而是印刷电路板上焊接7812的三个焊点发生焊点旋裂.使12 V电源时断时续所致。所谓焊点旋裂,是多年使用的旧彩电中常见的一种焊点劣变现象,其特征为焊点中部围绕被焊元件脚产生一道环形裂缝,这道裂缝造成了元件与电路的接触不良从而引发
Read the sixth issue of 2000 Xu Jianrong article “HFC-2175 color TV 7812 regulator block why burn repeatedly TDA3653B?”, I feel that the paper did put forward a common problem Horsepower HFC-2175 models, but the phenomenon of failure The description and the root cause of the fault are not very accurate, especially put forward their own opinions for Xu Jianrong and maintenance counterparts reference. I have overhaul more than one similar fault HFC-2175-type machine and found that the cause of the failure TDA3653B repeated burns, in fact, is not “poor 7812 regulator block”, but the printed circuit board soldering 7812 of three solder joints spin Cracked, causing intermittent 12 V power supply. The so-called solder joint spin-off, is used for many years old common in the old TV a spot of solder deterioration, which is characterized by solder joints around the central part of the foot to produce a ring-shaped cracks, cracks in this road caused by poor contact with the circuit components To trigger