1. Fault caused by host power supply

Black screen failure caused by damaged or poor quality of host power supply is very common. For example, if some new devices are added, the display will have a black screen failure. After eliminating the quality and compatibility problems of accessories, poor power quality and insufficient power are the main reasons for the failure. At this time, you may still hear the continuous alarm sound of 12 from the internal speaker. Replacing high-power and high-quality power supply is the best solution to this kind of fault. In addition, some motherboards have dual power interfaces of AT/ATX, and the wrong jumper setting can also lead to such failures.

2. Faults caused by the quality of accessories

Poor quality or damage of computer accessories is the main reason for the failure of the black screen of the display. For example, the motherboard (and the motherboard BIOS), memory, graphics cards and other issues. It will definitely cause a black screen failure. If the display light is orange, it is the fastest solution to replace the lower graphics card, memory and even the motherboard and cpu by replacement.

3. Connection quality between fittings

Poor contact caused by incorrect or loose connection between the memory graphics card and the motherboard is the main cause of black screen failure. Moreover, the connection problem between the graphics card and the monitor may also lead to this failure, until the AT power supply is plugged in incorrectly, or even the data cable of your hard disk or CD-ROM drive is connected backwards, which may also lead to the failure of starting the black screen.

4. Black screen failure caused by overclocking

Overclocking or overclocking components that are not suitable for overclocking will not only cause black screen failure, but also damage accessories in serious cases. In addition, overclocking or overclocking components are not suitable for overclocking, which will lead to poor heat dissipation, or the cooling fan is damaged or does not turn at all during normal use, which will lead to the collapse of system self-protection.

5. Black screen caused by other reasons

Others, such as the incorrect setting of the motherboard CMOS and the incorrect clearing of the motherboard BIOS jumper, will lead to black screen failure. At this time, you can change its settings according to the instructions of the motherboard. In addition, software conflicts, such as improper driver installation and DIY, such as BIOS refresh error, incorrect power management settings, hardware damage caused by malignant viruses (such as CIH), etc. , may cause the display black screen failure. When you encounter this kind of fault, you might as well think more and consider the cause of the fault, so as to know yourself and know yourself and get twice the result with half the effort.

The second is the black screen failure caused by the failure of the display itself.

According to the author's usual experience, the black screen failure caused by the failure of the display itself mainly has the following reasons:

1. The AC power supply is insufficient.

Insufficient external power supply causes some old monitors or some monitors with high power consumption to fail to start normally, which is also one of the reasons why the monitor itself fails to cause black screen. Or the external power supply voltage is unstable, too high or too low may cause the display to fail to work.

2. The power switch circuit is damaged

The failure of display switch circuit is the main reason for the failure of display black screen. Simple as power switch damage or internal short circuit; Common such as switch tube damage or its peripheral circuit components damage and so on.

3. The line output circuit is damaged

The failure of line output circuit or picture tube and its power supply circuit is also the main reason for the failure of display black screen. Especially for some inferior brand monitors that have been used for many years, it is more common that the high voltage package is damaged and the black screen is not displayed.

Third, the solution to the failure of the display black screen

How to repair the black screen failure of the display, we will put forward some ideas for your reference.

First of all, we can solve the display black screen failure caused by computer host failure from the following ideas:

1. Check the installation quality of accessories.

When you have a black screen failure when assembling a computer or replacing accessories, you should first check the installation quality of your accessories. For example, whether the memory module is installed correctly, whether it is in good contact with the motherboard slot, whether the graphics card and other plug-in cards are installed in place, and whether the relevant settings in BIOS and jumper selection on the motherboard are correct can be carefully set with reference to the instructions of the relevant cards. It is also necessary to focus on the quality of check card itself, and whether the relevant slots on the motherboard and the "golden finger" part on the card are contaminated by foreign objects and dirt.

In addition, whether the CPU is overclocked or "mistakenly overclocked" (especially some motherboards with soft jumpers, the "automatic" wrong setting of the system is more likely to cause such failures), whether the data cable of the hard disk or CD-ROM drive is connected backwards, etc. Need your consideration. Moreover, for this kind of problems, it is best to give priority to the "minimum system method" and "replacement method" for diagnosis, leaving only the motherboard, graphics card, memory and CPU for the host to try, especially the failure rate caused by the quality problems of memory chips is relatively high. If there is no problem, you can focus on checking the quality of other accessories. If the screen is still blank, you can focus on carefully installing and connecting these accessories and try again. If the problem cannot be solved, you can use related components.

In addition, it is very important that you also need to know the quality of the host power supply and power switch and whether they are connected normally, which may lead to a black screen of the whole machine, so you need to pay attention to it. If there is something wrong with the power supply, after you turn on the computer, you can see that the indicator light on the main chassis panel is not lit, and you can't hear the rotation sound of the power supply fan and the self-check sound of the hard disk in the host. This shows that your host system has no normal power supply at all. For this kind of problem, you should first check whether there is alternating current outside and use a pencil to see if there is electricity in the power socket. Next, test whether there is electricity on the side of the power cord connected to the host power supply. If necessary, use a multimeter to test whether the voltage is enough. If the voltage is too high or too low, it may lead to the automatic shutdown protection of the host power supply overvoltage or undervoltage circuit. If there are no problems above, you should first focus on the maintenance of the host and power switch and reset key, and also use the minimum system method and replacement method to unplug the power cord and signal cord of the host card and other equipment one by one, and then power on for debugging. If the power supply of the host computer resumes working when a device is unplugged, the newly unplugged device is damaged or improperly installed, resulting in a short circuit, which starts the short circuit protection circuit in the power supply and stops supplying power to the internal devices. Then you can focus on its connection, replace it first, and try again when necessary; In addition, it is also very important to check the quality of the power switch and reset key, and whether they are correctly connected with the motherboard, because the power switch and reset key on many inferior chassis often disconnect the internal metal contacts after being used for several times, resulting in a short circuit of the power supply, resulting in a black screen and no display. If the above inspection fails to solve the problem, please try to replace the power supply.

2. Listen to the sound and see the color to identify the fault

When the computer has a black screen fault, it is more often shown that the indicator light on the host panel lights up after the computer is turned on, and the fan in the machine rotates normally, but the PC speaker has an alarm sound; Or the related equipment inside the chassis, such as hard disk, performs normal self-check, but the display screen does not display. At this time, in addition to the maintenance according to the above methods, it is more important to learn to identify faults by identifying the error reporting law of PC speakers. In addition, it is also very useful to observe the lights on and off of the host or display to judge the fault when there is a fault.

For example, if the host performs a normal self-test, the display has a "black screen" failure. For this fault, we can focus on the idea of motherboard-graphics card-display card line-monitor. First of all, you can check whether the power indicator of the monitor is on. If it is normal, you can adjust the brightness and contrast buttons to eliminate such "common" false black screen failures. If there is no problem, you can focus on checking whether there is a problem with the connecting cable between the host graphics card and the monitor, whether the pointer in the plug on the cable is skewed or broken, and whether it is closely connected with the graphics card. In addition, you can remove this cable connector to see if the monitor can light up normally or try to connect the monitor to other hosts, so as to judge whether the failure is caused by the host or the monitor itself.

For another example, the display screen is black, and the speaker in the host computer emits a long, two or three short beeps or continuous beeps, indicating that there is a problem with the connection between the graphics card and the motherboard or between the graphics card and the monitor. You can focus on checking whether the slot contact is good or not, and try to replace the graphics card. If there is no improvement, you can initially explain that it is a problem with the motherboard, and you can try to take the graphics card to other motherboards. For another example, if there is a continuous long tone, it probably means that there is something wrong with the memory stick, so it is very important to check the installation contact between the memory and the memory stick. If there is a continuous short beep in the machine, it indicates a slight short circuit in the machine. The minimum system method and elimination method can be used to solve the problem until the short circuit position is found. In addition, if you hear two short beeps, it means that there may be something wrong with the motherboard, graphics card or monitor. If the monitor is not connected, there is something wrong with the video card. If it turns into a short beep, there is something wrong with the display terminal.

For the black screen failure caused by the monitor itself, we mainly provide you with more specific maintenance ideas from the following points.

1. Quick maintenance of black screen of display

If the monitor does not display after being turned on, the host can check whether the protection circuit of the monitor works due to too high or too low voltage, and whether the voltage of the accelerating electrode is normal. In addition, it is also important to check the following parts that are prone to problems, such as whether the fuse is blown, whether the rectifier bridge switch tube is broken, and whether the current limiting protection resistor is blown. Sometimes, you can see from the appearance that these parts are burnt black and other faults. Then focus on checking whether the key parts such as line output tube, transformer, low-frequency rectifier tube and high-frequency rectifier tube are damaged or their performance is degraded or virtual welding. As long as you start, you can quickly get rid of the general black screen failure of the display.

2. Fault judgment of line scanning circuit

The fault of line scanning circuit is an important reason for no grating and no screen after the display is powered on. For this kind of fault, we can focus on maintaining the line scanning circuit. First of all, we can check whether there is a problem with the line oscillation circuit. In my spare time, in addition to checking whether the components around the linear oscillator chip are damaged, I can try to replace the linear oscillator chip first. In addition, the above faults may be caused by the damage of the push tube or its abnormal operation, the damage of the output tube or the problem of the output line load. At this time, you can try to repair and replace these parts. But if there is anything wrong with the output circuit, it will return to normal after this overhaul and replacement.

3. Fault judgment of 3.CRT and its power supply circuit

Abnormal picture tube and its power supply circuit will also lead to the failure of grating black screen when the display is powered on. At this time, we can first check whether the filament of the kinescope is bright, and measure its filament power supply circuit with a meter to see if its filament voltage is normal. In addition, if it is found that the filament resistor is broken, it is enough to replace the filament current limiting resistor. If the filament of the kinescope is found to be broken, the kinescope needs to be replaced. If the above is normal, it is important to check whether the accelerating electrode voltage of the kinescope is normal, especially whether the connecting wire of the accelerating electrode voltage is broken and can be replaced. If there is high voltage, the line output transformer (high voltage package) can be replaced. The damage of this part is one of the main reasons for the failure of the black screen of the display. In addition, we can also check whether the cathode voltage and the video amplifier voltage are normal while overhauling the above. If the video amplifier voltage is not added or it is not normal at all, it is also one of the important reasons for the display to power on the black screen without grating.