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一合三洋牌79P型14英寸彩色电视机,开机后不到一分钟,亮度消失,但有噪音。关机后过一段时间再开机,又是如此。进一步观察发现开机后亮度比正常情况时强,图象扩大。因此估计是稳压电路有故障。查稳压输出电压达280V左右(正常应为220V),基本和整流输出电压相同。LA5112N(IC321)损坏。由于买不到LA5112N,也找不到合适的代用品,所以决定用晶体管代替。把原稳压电路进行了改装。改装后使用效果一直很满意。改装后的电路如图示。图中各元器件编号
A combination of Sanyo 79P 14-inch color TV, boot less than one minute, the brightness disappears, but there is noise. Shut down after a period of time before rebooting, and so on. Further observation found that the brightness after boot than normal, image expansion. Therefore, it is estimated that the regulator circuit is faulty. Check the voltage regulator output voltage up to 280V (normal should be 220V), the basic and rectified output voltage the same. LA5112N (IC321) damaged. Because can not buy LA5112N, can not find the suitable substitute, so decided to use the transistor instead. The original voltage regulator circuit was modified. Modified after using the effect has been very satisfied. The modified circuit as shown. The figure of the device number