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长虹C2592AV采用的是改进型东芝X56P开关电源,属并联自激式调宽型开关电源,其电源部分只设有过压保护电路(局部电路见图1所示)。其原理是:当输出电压过高时(含市电输入过高和稳压系统有故障导致),取样绕组经V817整流后的电压也将升高,被R818、R819分压后的取样电压也必升高,当超过6.2 V时,该电压将通过R822加至稳压管V820(6.2 V)负极并使之击穿,使可控硅V819被触发导通,通过C815、C814等将开关管V806基极电位拉低,使V806处于截
Changhong C2592AV using a modified Toshiba X56P switching power supply, is a parallel self-excited widened switching power supply, the power part of only over-voltage protection circuit (partial circuit shown in Figure 1). The principle is: when the output voltage is too high (including mains input is too high and the regulator system is faulty), the sampling winding voltage V817 rectifier will also be increased after the R818, R819 partial pressure sampling voltage Will be increased, when more than 6.2 V, the voltage will be added to the regulator through the R822 V820 (6.2 V) negative and make it breakdown, the SCR V819 is triggered to turn on, through the C815, C814, etc. will switch V806 base low potential, so V806 at the cut