Computer-activated black screen solution

When the computer starts to appear black screen, mostly because of bad contact or hardware damage caused. New installed or replacement hardware is more prone to black screen, if the replacement of hardware after the black screen, may be hard disk or optical drive data cable reverse, the system detects CPU error (excess is more likely to occur), the board of oblique plug caused by short circuit and bad contact, the expansion of the memory bar does not meet the requirements of the motherboard, and other reasons, Professional title computer experts told the computer to start black screen can be divided into power system failure caused by black screen, not self-test black screen failure and self-test failed three types of failure, the following we look at its phenomenon and reasons.

1. Power supply system failure causes black screen failure phenomenon

After the boot of the host panel LED is not lit, not hear the host power supply fan rotation and hard drive self-test sound, the entire system is silent. This is the phenomenon that the equipment in the host does not have normal power supply. Inspection and Treatment methods: power supply failure can be caused by AC power line circuit breaker, AC power supply voltage abnormality, microcomputer power failure or short circuit phenomenon in the host. Power supply failure is not necessarily the main engine damage caused by AC power supply voltage anomalies (overpressure or undervoltage), the host power supply no-load and the machine has short circuit phenomenon, the host power supply inside the protection circuit to start, automatically cut off the power output to protect the equipment inside the host.

(1) When the power supply system fails, first check whether the AC power supply is a host.

(2) Confirm the AC power supply access to the host, close the ear to the switching power supply, a short time to turn on the power switch power and pay attention to listen, if you hear the power of the internal issue of "HIV ..." the noise, indicating that the power supply in the "self-protection" working state, the reason is that the AC power supply is not normal or the Causes the protection circuitry inside the power supply to start. Use the following procedure to check the processing:

First, using a multimeter ac voltage file 250V Check the AC power supply voltage of the host power plug, if the AC voltage is more than 240V or less than 150V, the host power supply of overpressure and Undervoltage protection circuit will start, stop on the machine power supply, please switch to the power supply or UPS power supply for the host. If the AC power supply voltage is normal, unplug the internal interface card and other equipment power cord, signal line, and then power test machine, such as the removal of a device when the host power to restore work, it is just pulled out of the equipment damaged or improperly installed lead to short circuit, so that the power supply short-circuit protection circuit to start, stop to power the machine equipment.

If the power cord of all devices is unplugged, the power supply is still in no output state, which indicates a power failure, please repair the power supply. Note: The overhaul of the power supply should be connected to at least one load (such as optical drive or hard disk), such as no-load connected to the microcomputer power supply, computer power no-load protection circuit will start, stop output.

(3) If the host power supply is not working, please check the chassis installed on the front panel of the host power switch is normal, such as the power switch intact, is generally a power failure.

2. Non-Self test black screen fault failure phenomenon

The host panel indicator light is on and the fan is rotated normally, but the monitor is not displayed. At startup, the three LEDs in the upper-right corner of the keyboard are not shiny, and the "click ..." Sound and PC speaker alarm sound are not heard from the self-test memory. Check the processing method: By the phenomenon can be seen, the host power supply basic normal (do not exclude the host power failure), but failed to boot in the BIOS in the Self-Test program occurred a panic. The monitor, display card, memory, CPU and main plate should be checked primarily. Since there is no information about the failure of self-test black screen, the "Minimal system method" is usually used to check the processing. "Minimum system method" means to retain only the motherboard, memory, CPU, display cards, monitors and power supplies and other basic equipment, the first power to check the minimum system composed of these basic equipment, after checking to confirm the retention of the minimum system can work, and then further check other equipment. When using the minimum system method, it is recommended that you check the display to see if the monitor works correctly before you open the chassis to remove other devices. If only the smallest system is retained, the computer will not function properly after powerup, generally use the replacement method to check the memory bar, display card and CPU. Confirm that the monitor, memory, display card and CPU can work, the fault source only left the motherboard and power supply, distinguish between the motherboard failure or power failure is the easiest way to change a good power to try.

3. Self-Test failed black screen fault symptom

After the boot of the host panel LED light, fan normal rotation, can hear the hard disk disc rotation, self-test memory issued "Kabul ..." Sound and PC speaker alarm sound. I see three LEDs flashing in the upper right corner of the keyboard at startup, but no display on the monitor. Check the processing method: By the fault phenomenon that the main power supply basic normal, the motherboard most of the circuit is not faulty, and the memory of the first 64KB can be normal reading and writing, BIOS troubleshooting program began to run, and can be issued through the PC speaker alarm signal. This failure is primarily due to problems with hardware such as monitors, display cards, memory, motherboards, and power supplies. Most of these failures can be judged by the sound of the horn alarm to determine the approximate location of the fault.