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三、维修实例例1 开机时声、光、图正常,各项遥控和电视机面板上的按键均正常,但遥控关机后,不能再遥控开机。分析与检修:开机时声、光、图和各项控制功能正常,说明电源及功能电路都正常。开机时测量开关电源电压果然正常,但遥控关机后,开关电源输出电压只有CN403的③脚电压偏低(仅3.5V),判断故障在副电源转换电路,检查副电源转换电路,Q902内部开路,换之,故障排除。此故障系因Q902开路,故关机后,CPU失去工作电压,开/关机控制端(37)脚始终为低电
Third, the maintenance instance Example 1 boot sound, light, map normal, the remote control and the buttons on the TV panel are normal, but the remote control shutdown, you can no longer boot remotely. Analysis and Maintenance: boot sound, light, maps and various control functions are normal, indicating that the power and functional circuits are normal. Power switch to measure the power supply voltage is really normal, but the remote control shutdown, the switching power supply output voltage only CN403 pin voltage is low (only 3.5V), determine the fault in the secondary power conversion circuit, check the secondary power conversion circuit, Q902 internal open circuit, In other words, troubleshooting. This fault is due to Q902 open circuit, so shutdown, the CPU loses operating voltage, on / off control terminal (37) pin is always low