Here are the TOP 10 most common malfunctions of LCD monitors that I have personally experienced. The rating of malfunctions was compiled according to the personal opinion of the author, based on his experience working in a service center. You can take this as a universal repair manual for almost any LCD monitor from Samsung, LG, BENQ, HP, Acer and others. Here we go.
I divided the malfunctions of LCD monitors into 10 points, but this does not mean that there are only 10 of them - there are many more of them, including combined and floating ones. Many of the breakdowns of LCD monitors can be repaired with your own hands and at home.
at all, although the power light may blink. In this case, the monitor lights up for a second and goes out, turns on and turns off immediately. In this case, tugging at the cable, dancing with a tambourine and other pranks do not help. The method of tapping the monitor with a nervous hand usually doesn’t help either, so don’t even try. The reason for this malfunction of LCD monitors is most often the failure of the power supply board, if it is built into the monitor.
Recently, monitors with an external power supply have become fashionable. This is good because the user can simply change the power source in case of breakdown. If there is no external power source, you will have to disassemble the monitor and look for a fault on the board. in most cases it is not difficult, but you need to remember about safety precautions.
Before fixing the poor guy, let him stand for 10 minutes, unplugged. During this time, the high-voltage capacitor will have time to discharge. ATTENTION! It is DANGEROUS TO LIFE if the PWM transistor also burns out! In this case, the high-voltage capacitor will not discharge in an acceptable time.
Therefore, EVERYONE check the voltage on it before repairing! If dangerous voltage remains, then you need to discharge the capacitor manually through an insulated one of about 10 kOhm for 10 seconds. If you suddenly decide to short-circuit the leads, then protect your eyes from sparks!
Next, we proceed to inspect the monitor’s power supply board and replace all burnt parts - these are usually swollen capacitors, blown fuses, transistors and other elements. It is also MANDATORY to solder the board or at least inspect the soldering under a microscope for microcracks.
From my own experience I will say that if the monitor is more than 2 years old, then 90% there will be microcracks in the soldering, especially for LG, BenQ, Acer and Samsung monitors. The cheaper the monitor, the worse it is made at the factory. To the extent that the active flux is not washed away - which leads to failure of the monitor after a year or two. Yes, yes, just when the warranty ends.
when you turn on the monitor. This miracle directly indicates to us that the power supply is faulty.
Of course, the first thing you need to do is check the power and signal cables - they must be securely fastened in the connectors. A flickering image on the monitor tells us that the monitor's backlight voltage source is constantly jumping out of operating mode.
after the time has elapsed or does not turn on immediately. In this case, again, there are three common malfunctions of LCD monitors in order of frequency of occurrence - swollen electrolytes, microcracks in the board, faulty microcircuit.
With this malfunction, a high-frequency squeak from the backlight transformer can also be heard. It typically operates at frequencies between 30 and 150 kHz. If its operating mode is disrupted, vibrations can occur in the audible frequency range.
but the image is visible under bright light. This immediately tells us that LCD monitors are faulty in terms of backlighting. In terms of frequency of occurrence, it could be placed in third place, but it is already taken.
There are two options - either the power supply and inverter board burned out, or the backlight lamps are faulty. The last reason is not common in modern monitors. If the LEDs in the backlight fail, then only in groups.
In this case, the image may darken in places at the edges of the monitor. It is better to start repairs by diagnosing the power supply and inverter. The inverter is that part of the board that is responsible for generating a high-voltage voltage of about 1000 Volts to power the lamps, so under no circumstances should you try to repair the monitor under voltage. You can read about it on my blog.
Most monitors are similar in design, so there shouldn't be any problems. At one time, monitors simply fell off due to poor contact near the tip of the backlight. This can be cured by carefully disassembling the matrix in order to get to the end of the lamp and solder the high-voltage wiring.
A simpler way out of this unpleasant situation can be found if your friend-brother-matchmaker has the same monitor lying around, but with faulty electronics. It won’t be difficult to make two monitors of similar series and the same diagonal.
Sometimes even the power supply from a monitor with a larger diagonal can be adapted for a monitor with a smaller diagonal, but such experiments are risky and I do not recommend starting a fire at home. But in someone else’s villa, that’s a different matter...
Their presence means that the day before you or your relatives had a fight with the monitor over something outrageous.
Unfortunately, household LCD monitors are not equipped with shockproof coatings, and anyone can offend the weak. Yes, any decent poke with a sharp or blunt object will make you regret it.
Even if there is a small trace or even one broken pixel left, the stain will still begin to grow over time under the influence of temperature and voltage applied to the liquid crystals. Unfortunately, it is not possible to restore dead monitor pixels.
That is, a white or gray screen appears on your face. First, you should check the cables and try connecting the monitor to another video source. Also check whether the monitor menu is displayed on the screen.
If everything remains the same, look carefully at the power supply board. The power supply of an LCD monitor usually generates voltages of 24, 12, 5, 3.3 and 2.5 Volts. You need to use a voltmeter to check if everything is okay with them.
If everything is in order, then carefully look at the video signal processing board - it is usually smaller than the power supply board. It contains a microcontroller and auxiliary elements. You need to check if they are getting food. Touch the contact of the common wire with one (usually along the outline of the board), and with the other, walk along the pins of the microcircuits. Usually the food is somewhere in the corner.
If everything is in order regarding the power supply, but there is no oscilloscope, then we check all the monitor cables. On their contacts. If you find something, clean it with isopropyl alcohol. In extreme cases, you can clean it with a needle or scalpel. Also check the board with the monitor control buttons.
If all else fails, then perhaps you are faced with a case of broken firmware or microcontroller failure. This usually happens from surges in the 220 V network or simply from aging of the elements. Usually in such cases you have to study special forums, but it’s easier to use them for spare parts, especially if you know a familiar karateka who fights against unwanted LCD monitors.
This case can be easily treated - you need to remove the frame or back cover of the monitor and pull out the board. Most often there you will see a crack in the board or in the solder.
Sometimes there are faulty or . A crack in the board violates the integrity of the conductors, so they need to be cleaned and soldered, and the board must be glued to strengthen the structure.
This occurs due to aging of the backlight bulbs. According to my data, LED backlight does not suffer from this. It is also possible that the parameters of the inverter may deteriorate, again due to the aging of the components.
This often happens due to a bad VGA cable without an EMI suppressor -. If replacing the cable does not help, then it is possible that power interference has penetrated into the imaging circuits.
Usually they are eliminated from the circuit design by using filter capacitors for power supply on the signal board. Try replacing them and write to me about the result.
This concludes my wonderful rating of the TOP 10 most common malfunctions of LCD monitors. The bulk of data on breakdowns was collected based on repairs of such popular monitors as Samsung, LG, BENQ, Acer, ViewSonic and Hewlett-Packard.
This rating, it seems to me, is also valid for and. What is your situation on the LCD monitor repair front? Write to and in the comments.
Sincerely, Master Pike.
The most common questions when disassembling LCD monitors and TVs are how to remove the frame? How to release the latches? How to remove the plastic case? etc.
One of the craftsmen made a good animation explaining how to remove the latches from engagement with the body, so I’ll leave it here - it will come in handy.
To view animation— click on the image.
Users do not have to wonder why the monitor does not turn on very often. But, if the problem has already arisen, it can be quite difficult to cope with it.
And in such a situation, when the computer is left without the main means of displaying information, you should take as many steps as possible to restore it.
And this can be helped by studying the signs accompanying a device that does not turn on - a blinking light, a system reboot, and even the behavior of the computer itself.
The check will help you find out exactly what problem has occurred and help you fix it yourself or by contacting service.
Despite the fact that it seems to the user that it is the monitor that is not working, and everything is in order with the system unit, most often the problem is in the computer.
In this case, even after submitting the device for repair, you can receive an answer that it works quite normally.
And buying a new monitor will generally lead to a waste of money.
So, the main reasons why nothing is displayed on the display after pressing the power button could be:
In each of these cases, determining the cause of the malfunction when starting the computer is quite difficult - especially for a less experienced user who has not encountered such situations.
And yet, there are several techniques that can help not only check what the problem is, but also the degree of its complexity.
As a result, you can determine what will be needed to resolve the issue - is it worth trying to do it on your own or can you not do without a service.
A fairly common reason for the lack of an image on the monitor is the computer not turning on for some reason.
This happens, for example, when the power supply of the system unit fails or its power is not enough to support the operation of all systems connected to it (including the video card).
It is worth noting that modern gaming graphics cards have power consumption of 150–180 Watts, and AMD processors – up to 70 Watts.
And, trying to start a PC with a 300-watt power supply (taking into account the need for energy consumption from the motherboard, hard drive and optical drive), the user overloads the system and the computer does not turn on.
Although the same power supply is perfect for a nettop with a regular built-in video card.
A problem with the main power supply is detected by a message that lights up on the monitor before it turns on, and it disappears after just a couple of seconds.
It can be solved by replacing this element - a fairly simple procedure that requires a few minutes and a new power supply.
If the PC still works, but when you turn on the computer the built-in speaker produces a signal in the form of a squeak, the memory is faulty.
Advice! After cleaning the contacts or, in rare cases, replacing the RAM sticks (for such a radical solution, it is worth conducting additional tests), the problem usually goes away.
You can find out that it is the motherboard that is faulty in the same way as with a faulty power supply - the computer simply does not turn on, and the indicator on the monitor continues to light.
Although to clarify the reasons, you will most likely have to contact the service. But it is not the monitor that should be given there, but the system unit.
Additionally, you can make sure that the fault for the lack of a signal from the monitor lies with the computer, and not with the device itself that does not turn on, by connecting the monitor to a laptop, second computer, or video player.
This test option is ideal in case of a faulty system unit or an incorrectly configured system.
Since both the player and another PC will work with it normally, but the problem will have to be solved with the computer itself.
If the user has recently taken apart the computer and made some moves of modules on the motherboard, it is possible that the problem with the monitor is actually the graphics card.
A video card that is moved when cleaning the computer from dust may not work and the monitor, accordingly, will not turn on.
To check the board, you will have to disassemble the system unit back.
The absence of a result does not necessarily mean that the video card is not related to the problem.
Additionally, you can check it by switching the connecting cable from the monitor to the connector of the second graphics card - modern PCs, especially gaming ones, have two of them - built-in and discrete.
A normally working display indicates the need to change the video card or temporarily use a second one.
If you have two video cards, the problem occurs when the drivers for these devices conflict. Disabling the built-in graphics card in the BIOS will help eliminate it.
When the button blinks but the monitor does not work, you can assume that the problem is in the computer. If the indicator does not light up at all, the problem is in the display.
In extreme cases, even the matrix may be broken. But most often the problem is nutrition.
You can find out if the cause of the breakdown is a problem with the cord after checking its connection to the power supply. It is recommended to check the operation of the monitor with a different cable.
If the lamp still does not light up, the power supply is faulty and should be replaced.
Another common reason, which is already characterized by a burning light, is the lack of communication between the monitor and the computer.
In this case, the processor is working normally (there are no signals, the power supply fan is running), and the indicator indicates that power is supplied to the display, but there is still no image.
The connecting cable should be switched to another video card and returned again.
If the problem is not with the hardware, but on the computer, it is much easier to fix it. You don’t have to contact either a service or a warranty workshop.
All that is required from the user is to reconfigure the system or update the drivers.
The reason why the display does not work may be due to incorrect image settings. For example, incorrectly set frequency or screen resolution.
You can determine the problem by trying to connect the monitor to another computer, and get rid of it by resetting the settings after logging into safe mode, which may require another display.
Incorrectly installed drivers also lead to no images.
Although the monitor will turn on for a while and show at least the operating system boot screen.
They deal with the problem by switching to safe mode and updating the drivers.
Displaying the BIOS loading when you turn on the computer, and the subsequent disappearance of the image can be caused by serious problems with the operating system.
This situation is caused by viruses that have entered the PC from the Internet or from removable storage media, and other problems with the operation of system files.
If safe mode or restoring the system to a previous working state does not help, the OS is reinstalled.
This will take no more than 20–30 minutes, and the monitor’s performance will be restored automatically.
Although to get some extensions you will still have to install new drivers.
Why might the monitor not turn on? - Common causes
The computer turns on, all the coolers are spinning, the LEDs and indicators are glowing, but there is no image on the monitor. There is no image not from the video card, not from the motherboard. The problem turned out to be a damaged RAM stick.
Today I will talk about what to do if The computer turns on but the monitor does not work. Actually, a couple of days ago, looking at the night, I thought: “What a wonderful monitor I have, it’s almost six years old, and it’s never broken.” In the morning the monitor did not turn on 🙁
Those. Even the power indicator on the monitor did not light up. Naturally, the first thing I did was check the power cable by connecting the monitor through a different cable. Alas, this did not produce results - the monitor showed no signs of power. Taking a screwdriver in my hands, I unscrewed a couple of screws on the back cover of the monitor, and, just in case, reconnected it to the power supply... The monitor worked! However, it refused to turn on again the next morning.
In principle, two versions have emerged that the monitor turns on every other time:
Actually, I had to disassemble the monitor, namely the LG Flatron L1917S (do not pay much attention to the brand and model of the monitor, since similar malfunctions occur with different monitors). Having unscrewed the five screws on the back cover, I carefully began to “unfasten” the case latches. I found a recommendation on the Internet that it is convenient to use a plastic card for this so as not to damage the monitor case. Since I didn’t dare use my Sberbank card, I used a screwdriver.
Actually, inside modern LCD monitors there are not so many spill boards, so finding a rogue with a power supply is not particularly difficult, because it contains a connector for connecting the power cable.
It took a couple of seconds to identify the cause of the malfunction; it was clearly visible that one of the electrolytic capacitors (1000 uF x 16 V) of the monitor’s power supply was swollen.
The slightest swelling of the electrolytic capacitor, as a rule, leads to the fact that its capacity decreases sharply, which leads to increased ripple of the rectified voltage. Since modern computer technology is very sensitive to deviations in the power supply, it simply does not turn on. In this way, protection is activated, which prevents more serious damage.
Conclusion: any swollen electrolytic capacitor must be replaced, be it a monitor power supply, or, for example, a computer motherboard.
When replacing capacitors, it is necessary to install a capacitor whose capacitance and voltage are no less than those of the original one. You don’t have to pay much attention to the manufacturer. I found a suitable capacitor in a faulty power supply from the system unit. In the photo below is a “native” capacitor from SAMXON, on top is a capacitor from HEC. The capacitance and voltage of both capacitors are the same.
Below is the “native” capacitor. The capacitance and voltage of both capacitors are the same
Well, actually, after resoldering the capacitor, all that remains is to assemble the monitor. It is desirable that after assembly there are no “extra” screws left :)
Evgeny Mukhutdinov
If your LG LCD monitor won't turn on, the problem is most likely with the capacitors, but that's assuming its lights are on when it's plugged in. Otherwise, there can be quite a lot of reasons, from elementary fuses to complete failure of the microcircuit or power supply. In the format of this article, we will try to consider all the most current malfunctions of such equipment.
The problem may be related to the PC itself, the simplest example being a faulty video card. Such cases are not uncommon; the image simply will not be transmitted, that is, the screen will be black. This may give the impression that the LG monitor does not turn on at all. You can check whether this is the case in a simple way: unplug the monitor cord from the video adapter, the message “check the cable” should appear on the panel, but if it doesn’t, then the problem is in the device itself.
The same applies to breakdowns associated with the PC power supply; voltage may simply not be supplied or supplied in insufficient quantities. This fact is checked quite simply; the functionality of the coolers indicates the serviceability of the unit.
Before you sound the alarm and take the monitor to an LG service center, check the power cord; there is a possibility that it is broken or simply stopped functioning. The best way to check its functionality is to connect an identical cable to the monitor; if the situation repeats, then power is supplied to the device. You can also check the voltage in the cord using an indicator, if available, of course.
The power supply can easily be called the most unstable part of any monitor, so if your LG monitor does not turn on, and the previous tips did not help, the next step is to check the power supply. Here you will need a special tool, at least a simple multimeter, although there are visible damages, they can be detected during inspection. If there are blackened areas on the board, then the unit needs repair.
Capacitors can fail in any working microcircuit of the device, including in the power supply mentioned above; if they are swollen, then this is definitely the problem. However, a capacitor failure may not be noticeable at all upon closer inspection, so each of them must be tested. The device for such tests is called ESR-micro, this is the best option for such diagnostics. By checking the contacts of each capacitor, you can identify which ones are faulty; you can compare the indicators using the table below.
Accordingly, if the discrepancies in the device readings are significant, then the part must be replaced.
If you hear a click when you press the monitor's power button, then its fuses are working, but if not, then you should check them too. You can ring the contacts, if the multimeter emits a characteristic signal, then everything is in order and you can move on to the next step. If not, then you can change the fuse yourself; you don’t even need any tools.
If you have already checked everything you can, but the lg LCD monitor still does not turn on, do not rush to buy a new one, maybe the whole point is that the power button is broken. Check the integrity of the contacts; if one of them comes loose, you just need to solder it in place.
These tips should help you cope with the problem, but if this is not the case, seek help from qualified specialists.
