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接修一台松下TC—230D彩电,据用户说一个月前曾因无光、无声故障请人修过,已换过一块电源膜块STR456A,但拿回家后开机不到二个小时即又发生无图、无声故障。检查发现行管Q_(551)已击穿。焊开行电源限流电阻R_(556)一端,在C_(808)两端接一只50W300Ω电阻做假负载,开机+113V电压正常。检查其他元件无异常后,重新换了一只行管D_(1439),取下假负载,在R_(556)处串接一只
To repair a Panasonic TC-230D color TV, according to the user that a month ago because of no light, silent fault please repair, has replaced a power membrane block STR456A, but took home after boot less than two hours that occurred No picture, silent failure. Inspection found that the tube Q_ (551) has breakdown. Welding open line current limiting resistor R_ (556) at one end, both ends of C_ (808) connected to a 50W300Ω resistor to make a false load, the boot + 113V voltage is normal. After checking that there is no abnormality in other components, a new tube D_ (1439) is replaced, the dummy load is removed, and one of R_ (556) is connected in series