Nếu có không có video và không có tiếng bíp hệ thống trong quá trình khởi động (và nếu đó là riêng biệt - bạn chắc chắn loa được cắm vào bo mạch chủ), kiểm tra để xem nếu có sức mạnh từ việc cung cấp điện. Nếu bạn có thể nghe thấy các ổ đĩa và người hâm mộ bắt đầu quay và có thể nhìn thấy đèn LED thắp sáng trên bảng điều khiển phía trước, | Chapter 24 Diagnosis and Repair 383 System unresponsive If there s no video and no beep from the system during boot and if it s separate you re sure the speaker is plugged into the motherboard check to see if there s power from the power supply. If you can hear the disk drives and fans start to spin and can see LEDs lit on the front panel it s likely that the power supply is working. If you re skilled with a multimeter you can check this at the connectors where the power cables come into the motherboard. Relative to any of the black wires the red wire should be at 5 V the yellow at 12 the blue at -12 and the white at -5. You can do a simpler check on a disk drive connector Relative to either of the two middle ones the yellow wire should be 12 V while the red one should be 5 V. You have to have a load such as the motherboard or a disk connected to the power supply to do these measurements with the power supply connected to the motherboard or a hard disk. If there s no output from the power supply and you know the power line is feeding power to the system check these items Fuse Some power supplies have externally replaceable fuses accessible from the back of the computer. After unplugging the computer check if the fuse has blown and replace it if so. If the replacement fuse blows something s drawing too much power inside the computer. You might need to replace the power supply but you equally well might have a short circuit in the power wiring within the computer. Power switch A signal from the motherboard turns on an ATX power supply. That signal in turn derives from the power switch connected to the motherboard but is also conditioned by tests for processor and memory compatibility on the motherboard. Check the connection to the power switch. Check for additional power switches too some power supplies have a power switch on the back in addition to the system power switch on the front. Memory and processor The power supply won t start up without the processor seated
