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故障现象:打开电源开关,待机指示灯亮,无光栅,扬声器有微弱的“噗噗”声,按遥控器待机键无任何反应。分析与检修:从现象看故障范围应在电源、扫描或系统控制电路,打开机盖,给机器加电,测电源电压,B_1115V;B_219V;B_3180V正常,而B_424V;B_612V无输出,B_515V只有9V,有关电路如图1所示。V_(551)的b、e极均有27V的直流电压,与V_(552)基极连接的系统控制(30)脚POWER L ON/H OFF实测电压为3.5V,按遥控器待机键该脚电压无变化,由此看出故障是由(30)脚的高电平所致。
Symptoms: Turn on the power switch, the standby indicator light, no grating, the speaker has a weak “pop” sound, press the remote control standby button without any reaction. Analysis and Overhaul: From the phenomenon to see the fault range should be in the power, scanning or system control circuit, open the cover, power the machine to measure the power supply voltage, B_1115V; B_219V; B_3180V normal, and B_424V; B_612V no output, B_515V only 9V, The circuit shown in Figure 1. V_ (551) of the b, e are the most 27V DC voltage, and V_ (552) connected to the base of the system control (30) POWER L ON / H OFF measured voltage 3.5V, press the remote standby button No voltage change, which shows that the fault is caused by (30) feet high.