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例74 康佳 T2512A 型彩电故障现象:开机无反应.分析与检修:断开电源,将一只1.5 kΩ电阻焊在光电耦合器 N902③、④脚两端后通电,故障依旧,说明故障部位在 V906、V902、V903、R907等元件,检查相关元件,发现 V903击穿。更换同型号 V903后,故障排除。例75 康佳 T2512A 型彩电故障现象:开机无反应。分析与检修:接上假负载,通电后灯泡不发光,说明开关电源未启动或待机控制电路不良。将“光耦”N903的③脚用针头悬空后通电,故障依旧,说明开关电源电路的启动电路或正反馈电路不良。测开
Example 74 Konka T2512A color TV failure phenomenon: boot no response. Analysis and maintenance: disconnect the power supply, a 1.5 kΩ resistance welding in the optocoupler N902 ③, ④ both ends of the power after the fault remains the same, indicating the fault location in the V906, V902, V903, R907 and other components, check related components and found V903 breakdown. After replacing the same model V903, troubleshooting. Example 75 Konka T2512A color TV failure phenomenon: boot no response. Analysis and Maintenance: Connect the dummy load, the lamp does not light after power, indicating that the switching power supply is not started or standby control circuit is not good. The “optocoupler” N903 ③ pin vacant after the power supply, the fault still shows that the switching power supply circuit or the positive feedback circuit bad start. Open test