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例1 主机通电后,显示器上无光标,系统死机,但重复通电若干次,偶尔能启动,一旦启动,系统运行一切正常。检修:出现死机这类故障,应首先从电源开始检查。换一个新电源试机,一切正常,这说明原电源有故障,接上假负载(16Ω/20W),用万用表测±5V、±12V四组输出电压均正常。上述故障可能是PG(即电源好)信号失效所致。打开电源盒,检查PG信号产生电路,电路如图1
Example 1 After the host is powered on, there is no cursor on the display, the system crashes, but the power is repeatedly applied for several times, and can be started occasionally. Once started, the system runs normally. Overhaul: In the event of such failure, you should start with the power supply. For a new power test machine, everything is normal, indicating that the original power failure, connected to the fake load (16Ω / 20W), measured with a multimeter ± 5V, ± 12V four groups of output voltage are normal. The above fault may be due to PG (power good) signal failure. Open the power box, check PG signal generation circuit, the circuit shown in Figure 1