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[例1]打开电源开关,仅有电源指示灯亮,显示屏无任何显示,按OPEN/CLOSE键不能出盘。分析检修:打开机壳观察,发现接通电源时,机芯无任何动作,激光头既不发光,也无上下运动的聚焦动作。由此判断机芯下面的伺服电路板根本没有工作。首先检查供伺服电路板的+9V电源,只有+2.4V左右。该+9V是由固定在机壳上的LM7809提供的,测LM7809①脚输入端电压,+12V正常,将其③脚与后面的负载断开,再测输出电压,仍然很低,说明LM7809已损坏,将LM7809更换后,+9V电压恢复正常,试机故障排除。
[Example 1] Turn on the power switch, only the power indicator light, the display without any display, press the OPEN / CLOSE button can not exit. Analysis and Maintenance: Open the case observation found that the power switch, the movement without any action, the laser head neither light, nor up and down movement of the focusing action. Judging from the movement below the servo circuit board does not work. First check for servo circuit board +9 V power supply, only about +2.4 V. The +9 V is provided by the LM7809 fixed in the chassis, measuring LM7809 pin input voltage, + 12V normal, the ③ pin and the load after the disconnect, retest output voltage is still low, indicating that the LM7809 is damaged , The LM7809 replacement, +9 V voltage back to normal, test troubleshooting.