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[例一]故障现象:整机不工作,显示屏无任何显示。分析与检修:整机无显示,故障显然在电源部分,首先测PA插座的各脚电压发现M12V、AT5V、PC9V、PC5V分别为7.5V、0V、0V、0V,而其他各脚电压基本正常。由于PC5V和PC9V是受IC801的控制,只有IC801在正常工作状态时,⑧脚输出控制指令,PC5V、和PC9V电压才有输出。所以应首先检查AT5V电源支路有关原件,测IC903的输入电压为8V,正常,测输出电压为0V,不正常,断电测IC903(7805)输出端在路电阻为0Ω,怀疑IC903损坏,取下测量已击穿,更换后故障排除。
[Example 1] Symptom: The machine does not work, the display without any display. Analysis and Maintenance: The machine no display, the fault is clearly in the power supply section, first measure the voltage of each pin PA socket found M12V, AT5V, PC9V, PC5V were 7.5V, 0V, 0V, 0V, while the other pin voltage is normal. Because PC5V and PC9V are controlled by IC801, only IC801 is in normal working state, ⑧ foot output control command, PC5V, and PC9V voltage have output. Therefore, we should first check the AT5V power supply branch about the original test IC903 input voltage is 8V, normal, the measured output voltage is 0V, abnormal, power outage test IC903 (7805) output resistance in the road 0Ω, suspected IC903 damage, take Under the measured breakdown, replacement troubleshooting.