开机测量,5V、12V电压均正常,测量24V供电只有22V,且左右轻微抖动。拆下电路板,将排插XP812的STB与5V-S短路,测量发现24V供电仍为22V,且轻微抖动,说明【故障】部位在24V产生电路,试代换光电耦合器N806后【故障】依旧。将光电耦合器脚短路,证明【故障】部位在取样电路,试代换集成电路后,【故障】现象依旧。测量R882等电阻zuzhi阻值均正常,拆下电容供电电压正常,测量电容<发现该电容的容量已经变小,更换电容后,整机恢复正常,【故障】排除 |
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