DIY repair monitors

Until 2004-2005, CRT monitors and televisions, or, in other words, having a kinescope in their composition were distributed in mass use. They are also, like televisions, called monitors and CRT (cathode ray tube) type monitors. But progress does not stand still, and at one time LCD TVs were released, which included an LCD (liquid crystal) matrix. Such a matrix must be well illuminated by 4 CCFL lamps located on both sides, top and bottom.

This applies to 17 - 19 inch monitors and TVs. Larger TVs and monitors may have six or more lamps. Such lamps in appearance resemble ordinary fluorescent lamps, but, in contrast, are much smaller in size. Of the differences, such lamps will not have 4 contacts, as in fluorescent lamps, but only two, and their operation requires a high voltage - over a kilovolt.

Monitor backlight connector

So, after 5-7 years of operation, these lamps often become unusable, malfunctions are typical for ordinary fluorescent lamps. Here is some additional information. First, reddish tints appear in the image, a slow start, in order for the lamp to light up, it needs to blink several times. In severe cases, the lamp does not light up at all. The question may arise: well, one lamp has gone out, they are standing above and below the matrix, usually two pieces installed parallel to each other, let only three of them burn and the image will only be dimmer. But not everything is so simple.

The fact is that when one of the lamps goes out, the protection on the PWM controller of the inverter will work, and the backlight, and most often the entire monitor, will turn off. Therefore, when repairing LCD monitors and televisions, if there is a suspicion of an inverter or lamps, it is necessary to check each of the lamps with a test inverter. I purchased such a test inverter on Aliexpress as in the photo below:

Test inverter with Ali express

This test inverter has a connector for connecting an external power supply, wires with crocodiles at the output, and connectors for connecting plugs, monitor lamps. There is information on the network that such lamps can be checked for operability using an electronic ballast from energy-saving lamps, with a burned-out lamp spiral, but having working electronics.

Electronic ballast from an energy-saving lamp

What if, using a test inverter or electronic ballast from an energy-saving lamp, you found out that one of the lamps has become unusable and does not light up at all when connected? You can, of course, order lamps on Aliexpress, by the piece, but given that these lamps are very fragile, and knowing the Russian Post, you can easily assume that the lamp will come broken.

Broken Matrix LCD Monitor

You can also remove the lamp from a donor, such as a monitor with a broken matrix. But it is not a fact that such lamps will last a long time, since they have already partially exhausted their resource. But there is another option, a non-standard solution to the problem. You can load one of the outputs from transformers, and there are usually 4 of them, according to the number of lamps on 17 inch monitors, resistive or capacitive load.

Power supply and monitor inverter board

If everything is clear with a resistive one, it can be an ordinary powerful resistor, or several connected in series or in parallel, in order to gain the required rating and power.But this solution has a significant drawback - resistors will generate heat when the monitor is operating, and given that it is usually hot inside the monitor case, additional heating may not please electrolytic capacitors, which, as you know, do not like prolonged overheating and swell.

Swollen capacitors monitor power supply

As a result, if it were, for example, a 400-volt network electrolytic capacitor, that same big barrel known to everyone from the photo, we could get a burnt-out mosfet or a PWM controller microcircuit with a built-in power element. So, there is another way out: to extinguish the required power using a capacitive load, a capacitor 27 - 68 PicoFarad and an operating voltage of 3 Kilovolts.

This solution has some advantages: there is no need to place bulky heating resistors in the case, but it is enough to solder this small capacitor to the contacts of the connector to which the lamp is connected. When choosing the rating of the capacitor, be careful not to solder any ratings, but strictly according to the list at the end of the article, in accordance with the diagonal of your monitor.

We solder the capacitor instead of the backlight lamp

If you solder a smaller capacitor, your monitor will turn off as the inverter will still go into protection due to the fact that the load is small. If you solder a larger capacitor, the inverter will work with overload, which will negatively affect the service life of the mosfets at the output from the PWM controller.

If the mosfets are broken, the backlight, and possibly the entire monitor, will also not be able to turn on, since the inverter will go into protection. One of the signs of overloading the inverter will be extraneous sounds coming from the inverter board, such as hiss. But with the VGA cable disconnected, sometimes a slight hiss coming from the inverter board is normal.

Selection of capacitor ratings for the monitor

The photo above shows imported capacitors, there are also their domestic counterparts, which usually have a slightly larger size. I once soldered ours, domestic at 6 KiloVolts - it all worked. If your radio store does not have capacitors for the required operating voltage, but there are, for example, 2 KiloVolts, you can solder 2 capacitors 2 times larger in series, while their total operating voltage will increase and allow them to be used for our purposes.

Likewise, if you have capacitors 2 times smaller, 3 Kilovolts, but not at the required rating, you can solder them in parallel. Everyone knows that series and parallel connection of capacitors are considered according to the inverse formula of series and parallel connection of resistors.

Parallel connection of capacitors

In other words, when capacitors are connected in parallel, we use the formula for the series connection of resistors or their capacitance is simply added, with a series connection, the total capacitance is calculated using a formula similar to the parallel connection of resistors. Both formulas can be seen in the figure.

DIY monitor repair

Many monitors were already directed in a similar way, the backlight brightness dropped slightly, due to the fact that the second lamp on top or bottom of the monitor or TV matrix still functions and gives, albeit less, but sufficient illumination so that the image remains quite bright.

Condensers in the online store

Such a solution for home use may well suit a novice radio amateur, as a way out of this situation, if the alternative is to repair in a service costing one and a half to two thousand, or buy a new monitor. These capacitors cost only 5-15 rubles per piece in radio stores in your city, and any person who knows how to hold a soldering iron in their hands can perform such repairs. Successful repairs to everyone! Especially for Radioskot.ru - AKV.

In the previous articles devoted to the repair of computer power supplies, we learned how to find and fix simple breakdowns. Let's take a simple look at how switching power supplies differ from conventional transformer ones? The switching power supply unit is capable of delivering significant power to the load with a rather modest size. For this reason, almost all modern technology, with the exception of audio technology (it’s taboo there), is powered by impulses.

Oh yeah, what's all this about? The fact is that a switching power supply is installed in the monitors. And the knowledge that we gained from previous articles on the repair of power supplies is fully applicable to the repair of power supplies for monitors. The difference is purely in the dimensions and layout of radio components.

The giblets of a power supply for a computer look something like this:

And the power supply for the monitor is something like this:

But there is also a significant difference. In power supplies for monitors with LCD backlight, you can see the high-voltage part. He's an inverter. His presence is indicated by inscriptions such as "High Voltage" and terminals for connecting lamps. Please note that the voltage supplied to the lamps is over 1000 volts! Therefore, it is better not to touch and even more so not to lick this part when you turn on the Monica in the network.

By the way, what is the difference between LCD backlit monitors and LED backlit monitors? In LCD monitors, we use fluorescent lamps for backlighting. This is almost the same as fluorescent lamps, just reduced several times.

These lamps are located at the top and bottom of the display and illuminate the image.

If you turn them off, the image will be so dim that you think the display is off altogether. Only a close inspection under lighting can show that there is still an image on the display. This trick will be useful to us to determine lamp malfunctions.

LED monitors use LEDs for backlighting, which are located either on the sides of the display, or behind it.

Now all manufacturers of monitors and TVs have switched to LED backlighting, since it cuts power consumption by almost half and is much more durable than LCD.

A modern LCD monitor consists of only two boards: a scaler and a power supply

Scaler Is a monitor control board. His brain. Here the monik converts the digital signal into colors on the display, and also contains various settings. It contains the processor, flash-memory, where the monitor's firmware is written, and EEPROM-memory, in which the current settings are saved.

Power Supply, in fact, provides power to the monitor circuit. As I said, it can contain an inverter for monics with LCD backlight. In monitors with LED backlighting, there is no inverter.

So, what are the most common monitor breakdowns and what causes them? These are, of course, electrolytic capacitors in the power supply filter.

This is one of the most common LCD monitor breakdowns. Conder can be re-soldered easily and easily. Sometimes the boards do not have a standard capacitor rating, for example 680 or 820 microfarad x 25 volts. If you are faced with swollen capacitors of this denomination and they were not in your radio store, do not rush to go around all the radio stores in your city in search of the exact same denomination. This is exactly the case when "a lot is not harmful." Any electronics engineer will tell you this. Feel free to put 1000 microfarads x 25 volts and everything will work fine. Even more is possible.

Due to the fact that the power supply emits heat during operation, which adversely affects the life of the capacitors, be sure to put capacitors with the designation "105C" on the case. Also, after re-soldering the capacitors, it does not hurt to check the secondary circuit fuse, which is often a simple SMD resistor with zero resistance, frame size 0805, located on the back of the board from the routing side.

And one more nuance, at the output of the power supply, in front of the power connector itself going to the scaler, an SMD zener diode is often placed

If the voltage on it exceeds the nominal, it goes into a short circuit and thereby disconnects our monitor through the protection circuits. You can replace it with any one that is suitable for the voltage rating. Can even be used with pins

After everything is done and repaired, we check with a multimeter the voltage at the power connector, which goes to the scaler. All tensions are signed there. Make sure they match the readings of the multimeter

Problems in the high-voltage part of the power supply (inverter).

If possible, then first of all, always look for the schematics of the device being repaired. Let's take a look at the high voltage part of one of the monitors.

If you see that the monitor power supply fuse is blown, it means that the resistance between the power wires of the monitor cord (input resistance) has become very low at some point (short circuit). Somewhere around 50 ohms or less, which in turn, according to Ohm's law, caused an increase in the current in the circuit. Because of the high current, the fuse wires burned out.

If the fuse is in a metal-glass case, we can insert absolutely any fuse into the mount and ring the resistance between the pins of the plug with a multimeter in 200 Ohm Ohmmeter mode. If our resistance is zero and up to 50 ohms, which is most often the case, then we are looking for a broken radio element that rings to zero or to ground.

Insert the fuse, switch the multimeter to 200 ohms and connect it to the power plug. We make sure that the resistance is very small. Further, we are in no hurry to remove the fuse. So let's see, according to the diagram, which radio components can be short-circuited with us. In the photo, the parts that need to be checked in case of a short circuit in the high-voltage part are highlighted in colored frames

All these procedures for measuring resistance are done in order to call the listed parts one by one. That is, we solder and again measure the resistance through the plug. As soon as we get a high resistance at the input of the plug, replacing the defective radio element, then we can safely plug the plug into the outlet.

Monitor backlight disappears

The problem is this: our monitor turns on, it works for 5-10 seconds and goes out. This indicates that one of the display backlight lamps has become unusable. Before that, part of the screen may blink a little. In this case, the inverter will go into protection, which will manifest itself in the automatic shutdown of the monitor backlight.

In order for us to check the lamps and exclude the defective one, we buy a high-voltage capacitor 27 picofarads x 3 kilovolts for 17 "monitors, 47 pF for 19" monitors and 68 pF for 22 "monitors from a radio store.

This capacitor must be soldered to the pins of the connector to which the backlight is connected. The lamp itself, of course, must be turned off. By connecting the capacitor in turn to each connector, we ensure that the inverter stops going into protection.

The monitor will work, although it will be a little dim. This is useful as a temporary solution while the lamp is expected to be delivered, for example from China, or as a permanent solution if it is impossible for one reason or another to replace the backlight.

Of course, rarely does anyone do that. The very trick is to turn off the protection on the PWM chip itself))). To do this, google "remove the protection of the inverter xxxxxxx" Instead of "xxxxxx" we put the brand of our PWM microcircuit. Somehow I turned off the protection on the monitor with the TL494 PWM microcircuit according to the diagram below by soldering a 10 Kiloohm resistor. Monique has been working for the second year now. No complaints).

Today I want to share with you the experience of repairing a monitor with my own hands. I repaired my old one LG Flatron 1730s... Like this:

This is a 17 "LCD monitor.I must say right away that when there is no image on the monitor, we (at work) immediately refer such copies to our electronics engineer and he deals with them, but there was an opportunity to practice 🙂

To begin with, let's understand the terminology a little: earlier, CRT monitors (CRT - Cathode Ray Tube) were in use. As the name implies, they are based on a cathode ray tube, but this is a literal translation, it is technically correct to talk about a cathode ray tube (CRT).

Here is a disassembled sample of such a "dinosaur":

Nowadays the LCD type of monitors (Liquid Crystal Display) or simply LCD is in vogue. These designs are often referred to as TFT monitors.

Although, again, if we speak correctly, then it should be like this: LCD TFT (Thin Film Transistor - screens based on thin-film transistors). TFT is simply the most common variety, more precisely, LCD (liquid crystal) display technology.

So, before we start repairing the monitor ourselves, let's consider what “symptoms” did our “patient” have? In short: there is no image on the screen... But if you look a little more closely, then various interesting details began to emerge! 🙂 When turned on, the monitor showed an image for a split second, which immediately disappeared. At the same time (judging by the sounds), the system unit of the computer itself worked properly and the operating system was loaded successfully.

After waiting for a while (sometimes 10-15 minutes), I found that the image appeared spontaneously. Repeating the experiment several times, I was convinced of this. Sometimes for this, however, you had to turn off and turn on the monitor with the "power" button on the front panel. After resuming the picture, everything worked without interruptions until the computer was turned off. The next day, history and the whole procedure were repeated again.

Moreover, I noticed an interesting feature: when the room was warm enough (the season is no longer summer) and the batteries were heated fairly, the idle time of the monitor without an image was reduced by five minutes. There was a feeling that it warms up, reaching the desired temperature regime and then works without problems.

This became especially noticeable after one day the parents (the monitor was with them) turned off the heating and the room became quite fresh. In such conditions, the image on the monitor was absent for about 20-25 minutes, and only then, when it got hot enough, did it appear.

According to my observations, the monitor behaved exactly the same as a computer with certain problems of the motherboard (capacitors that have lost capacity). If it is enough to warm up such a board (let it run or direct a heater towards it), it normally “starts up” and, quite often, works without interruptions until the computer is turned off. Naturally, this is - until a certain moment!

But at the early stage of diagnosis (before opening the patient's case), it is highly desirable for us to make the most complete picture of what is happening. According to it, we can roughly navigate in which node or element the problem is? In my case, after analyzing all of the above, I thought about the capacitors located in the power supply circuit of my monitor: we turn on - there is no image, the capacitors are warming up - it appears.

Well, it's time to test this assumption!

Let's disassemble! First, using a screwdriver, unscrew the screw that secures the bottom of the stand:

Then, - remove the corresponding screws and remove the base of the stand attachment:

Next, using a flat-tipped screwdriver, we pry the front panel of our monitor and in the direction indicated by the arrow, we begin to carefully separate it.

Slowly, we move along the perimeter of the entire matrix, gradually removing the plastic latches holding the front panel from their seats with a screwdriver.

After we disassembled the monitor (separated its front and rear parts), we see the following picture:

If the “insides” of the monitor are attached to the back panel with adhesive tape, peel it off and remove the matrix itself with the power supply and control board.

The back plastic panel remains on the table.

Everything else in the disassembled monitor looks like this:

This is how the “filling” looks in the palm of my hand:

Let's show a close-up of the panel of settings buttons that are displayed for the user.

Now, we need to disconnect the contacts connecting the cathode backlight lamps located in the monitor matrix with the inverter circuit responsible for their ignition. To do this, we remove the aluminum protective cover and see the connectors under it:

We do the same on the opposite side of the monitor's protective casing:

Disconnect the connectors from the monitor inverter to the lamps. Who cares, the cathode lamps themselves look like this:

They are covered on one side with a metal casing and are located in it in pairs. The inverter “lights up” the lamps and adjusts the intensity of their light (controls the brightness of the screen). Now, instead of lamps, LED backlights are increasingly used.

Advice: if you find that on the monitor suddenly the image is gone, take a closer look (if necessary, illuminate the screen with a flashlight). Perhaps you will notice a faint (faint) image? There are two options here: either one of the backlight lamps is out of order (in this case, the inverter simply goes “in defense” and does not supply power to them), remaining fully operational. The second option: we are dealing with a breakdown of the inverter circuit itself, which can either be repaired or replaced (in laptops, as a rule, they resort to the second option).

By the way, the laptop inverter is located, as a rule, under the front outer frame of the screen matrix (in the middle and bottom of it).

But we got distracted, we continue to repair the monitor (more precisely, for now, chuck it) 🙂 So, having removed all the connecting cables and elements, we disassemble the monitor further. We open it like a shell.

Inside we see another cable connecting, protected by another casing, the matrix and monitor backlight lamps with the control board. Peel off the scotch tape up to half and see under it a flat connector with a data cable in it. We carefully remove it.

We put the matrix separately (we will not be interested in it in this repair).

This is how it looks from the back:

Taking this opportunity, I want to show you the disassembled monitor matrix (recently they tried to repair it at work). But after analysis, it became clear that it would not be possible to fix it: some of the liquid crystals on the matrix itself burned out.

In any case, I shouldn't have seen my fingers behind the surface so clearly! 🙂

The die is secured in a frame that holds and holds all of its parts together using snug plastic snaps. In order to open them, you will have to work thoroughly with a flat screwdriver.

But with the type of do-it-yourself monitor repair that we are doing now, we will be interested in another part of the design: the control board with the processor, and even more so, the power supply of our monitor. Both of them are shown in the photo below: (photo - clickable)

So, in the photo above, on the left, we have a processor board, and on the right, a power board combined with an inverter circuit. A processor board is often referred to as a scaler board (or circuit).

The scaler circuit processes the signals coming from the PC. In fact, a scaler is a multifunctional microcircuit, which includes:

• microprocessor
• a receiver (receiver) that receives a signal and converts it into the desired type of data, transmitted via digital interfaces for connecting a PC
• an analog-to-digital converter (ADC) that converts the input analog R / G / B signals and controls the resolution of the monitor

In fact, a scaler is a microprocessor optimized for the task of image processing.

If the monitor has a frame buffer (random access memory), then work with it is also carried out through the scaler.For this, many scalers have an interface for working with dynamic memory.

But we - again distracted from the repair! Let's continue! 🙂 Let's take a close look at the monitor power combo board. We will see such an interesting picture there:

As we assumed at the very beginning, remember? We see three swollen capacitors requiring replacement. How to do it correctly is described here in this article of our site, we will not be distracted once again.

As you can see, one of the elements (capacitors) swelled not only from above, but also from below, and some of the electrolyte flowed out of it:

To replace and effectively repair the monitor, we will need to completely remove the power board from the casing. We unscrew the fastening screws, take out the power cable from the connector and take the board in our hands.

Here is a photo of her back:

I want to say right away that quite often the power board is combined with the inverter circuit on one PCB (printed circuit board). In this case, we can talk about a combination board, represented by the power supply of the monitor (Power Supply) and the inverter of the backlight (Back Light Inverter).

In my case, this is exactly the case! We see that in the photo above, the lower part of the board (separated by a red line) is, in fact, the inverter circuit of our monitor. It happens that the inverter is represented by a separate PCB, then there are three separate boards in the monitor.

The power supply (the upper part of our PCB) is based on the FAN7601 PWM controller microcircuit and the SSS7N60B field-effect transistor, and the inverter (its lower part) is based on the OZL68GN microcircuit and two FDS8958A transistor assemblies.

Now we can safely start repairing (replacing capacitors). We can do this by conveniently placing the structure on the table.

This is how the area of ​​interest to us will look after removing faulty elements from it.

Let's take a close look at what nominal capacitance and voltage do we need to replace the elements soldered from the board?

We see that this is an element with a rating of 680 microfarads (mF) and a maximum voltage of 25 volts (V). In more detail about these concepts, as well as about such an important thing as maintaining the correct polarity when soldering, we talked with you in this article. So, let's not dwell on this again.

Let's just say that we have failed two 680 mF capacitors with a voltage of 25V and one at 400 mF / 25V. Since our elements are connected in parallel to the electrical circuit, we can safely use two 1000 mF capacitors instead of three capacitors with a total capacity (680 + 680 + 440 = 1800 microfarads), which will add up to the same (even greater) capacitance.

The capacitors removed from our monitor board look like this:

We continue to repair the monitor with our own hands, and now it is time to solder the new capacitors in place of the removed ones.

Since the elements are really new, they have long “legs”. After soldering into place, just carefully cut off their excess with side cutters.

As a result, we got it like this (for the sake of order, for two capacitors of 1000 microfarads, I put an additional element with a capacity of 330 mF on the board).

Now, we carefully and carefully reassemble the monitor: fasten all the screws, connect all cables and connectors in the same way, and, as a result, we can proceed with an intermediate test run of our half-assembled structure!

Advice: there is no point in immediately putting the entire monitor back together, because if something goes wrong, we will have to disassemble everything from the very beginning.

As you can see, the frame, signaling the absence of a connected data cable, appeared immediately. This, in this case, is a sure sign that the repair of the monitor with our own hands was successful with us! 🙂 Previously, until the malfunction was corrected, there was no image at all until it warmed up.

Mentally shaking hands with ourselves, we assemble the monitor to its original state and (for testing) we connect it with a second display to the laptop. We turn on the laptop and see that the image immediately "went" to both sources.

Q.E.D! We just repaired our monitor ourselves!

note: To find out what other types of TFT monitor malfunctions there are, follow this link.

That's all for today. Hope this article was helpful to you? See you next on the pages of our site 🙂

Here are the TOP 10 most common LCD monitor malfunctions that I felt the hard way. The fault rating was compiled according to the author's personal opinion, based on the experience of working in the 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, including combined and floating ones. Many of the breakdowns of LCD monitors can be repaired by hand or at home.

in general, although the power indicator may be blinking. At the same time, twitching the cable, dancing with a tambourine and other pranks do not help. Tapping the monitor with a nervous hand usually doesn't work either, so don't even try. The reason for such a 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 source have become fashionable. This is good because the user can simply change the power supply in the event of a breakdown. If there is no external power source, then you will have to disassemble the monitor and look for a malfunction on the board. In most cases, it is not difficult to disassemble an LCD monitor, but you need to remember about safety.

Before fixing the poor fellow, let him stand for 10 minutes, unplugged. During this time, the high-voltage capacitor will have time to discharge. ATTENTION! DANGEROUS TO LIFE if the diode bridge and the PWM transistor burn out! In this case, the high voltage capacitor will not discharge in an acceptable time.

Therefore, EVERYONE before repairing to check the voltage on it! If a dangerous voltage remains, then the capacitor must be manually discharged through an insulated resistor of about 10 kOhm for 10 seconds. If you suddenly decide to close the terminals with a screwdriver, then keep your eyes away from sparks!

Next, we proceed to inspect the monitor power supply board and change all burned-out 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 - if the monitor is more than 2 years old - then 90% that 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. Up to the point that the active flux is not washed out - which leads to the failure of the monitor after a year or two. Yes, yes, just when the guarantee ends.

when the monitor is turned on. This miracle directly indicates to us a malfunction of the power supply.

Of course, the first step is to check the power and signal cables - they must be securely fastened in the connectors. A blinking image on the monitor tells us that the monitor backlight voltage source is constantly jumping off the operating mode.

The most common reason for this is swollen electrolytic capacitors, microcracks in the solder and a faulty TL431 microcircuit. Swollen capacitors most often cost 820 uF 16 V, they can be replaced with a larger capacity and a higher voltage, for example, the cheapest and most reliable ones are Rubycon 1000 uF 25 V capacitors and Nippon 1500 uF 10 V capacitors. 105 degrees) Nichicon 2200 uF 25 V. Everything else will not last long.

after the time has elapsed or does not turn on immediately. In this case, again, there are three frequent malfunctions of LCD monitors in order of frequency of occurrence - swollen electrolytes, microcracks in the board, faulty TL431 microcircuit.

With this fault, a high-frequency squeak of the backlight transformer can also be heard. It usually operates at frequencies between 30 and 150 kHz.If the mode of its operation is violated, oscillations can occur in the audible frequency range.

but the image is viewed under bright light. This immediately tells us about a malfunction of LCD monitors in terms of the backlight. In terms of the frequency of occurrence, it could be put in third place, but it has already been taken there.

Option two - either the power supply and inverter board burned out, or the backlight lamps are faulty. The latter reason is not common in modern monitors with LED backlighting. If the LEDs are backlit and fail, then only in groups.

In this case, there may be a darkening of the image in places at the edges of the monitor. It is better to start repairs with diagnostics of the power supply and inverter. An inverter is the part of the board that is responsible for the formation of a high-voltage voltage of the order of 1000 volts to power the lamps, so in no case should you try to repair the monitor under voltage. You can read about repairing the Samsung monitor power supply in my blog.

Most monitors are similar in design, so there shouldn't be any problems. At one time, monitors simply rained down with a breakdown in contact near the tip of the backlight. This is treated with the most careful disassembly of the matrix to get to the end of the lamp and solder the high voltage wires.

If the backlight itself burns out, I would suggest replacing it with the LED backlight bar that usually comes with your inverter. If you still have questions - write to me by mail or in the comments.

These are the nastiest LCD monitor malfunctions in the life of any computer technician and user, because they tell us that it's time to buy a new LCD monitor.

Why buy new? Because your pet's matrix is ​​90% unusable. Vertical stripes appear when the contact of the signal loop with the contacts of the matrix electrodes is broken.

This can only be cured by careful application of anisotropic adhesive tape. Without this anisotropic glue, I had a bad experience repairing a Samsung LCD TV with vertical stripes. You can also read how the Chinese repair such strips on their machines.

An easier way out of this unpleasant situation can be found if your brother-in-law friend has the same monitor lying around, but with faulty electronics. It will not be difficult to blind from two monitors of similar series and the same diagonal.

Sometimes even a power supply unit 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. Here in someone else's villa - that's another matter ...

Their presence means that the day before, you or your relatives had a fight with the monitor because of something outrageous.

Unfortunately, household LCD monitors do not provide shockproof coatings and anyone can offend the weak. Yes, any decent poke with a sharp or blunt object into the LCD monitor matrix will make you regret it.

Even if there is a small trace or even one broken pixel, over time, the spot will begin to grow under the influence of temperature and voltage applied to the liquid crystals. Unfortunately, it will not work to restore the dead pixels of the monitor.

That is, there is a white or gray screen on the face. First, you should check the cables and try connecting the monitor to a different video source. Also check if the monitor menu is displayed on the screen.

If everything remains the same, we look closely at the power supply board. In the power supply unit of the LCD monitor, voltages of 24, 12, 5, 3.3 and 2.5 volts are usually formed. It is necessary to check with a voltmeter if everything is in order with them.

If everything is in order, then we carefully look at the video signal processing board - it is usually smaller than the power supply board. It has a microcontroller and auxiliary elements. You need to check if food comes to them. With one probe, touch the contact of the common wire (usually along the contour of the board), and with the other, go over the terminals of the microcircuits. Usually food is somewhere in the corner.

If everything is in order in the power supply, but there is no oscilloscope, then we check all the monitor loops. There should be no carbon deposits or darkening 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 ribbon cable and the board with the monitor control buttons.

If all else fails, then perhaps you are faced with a case of a failed firmware or a failure of the microcontroller. 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 start up for spare parts, especially if you have a familiar karate fighter fighting against objectionable LCD monitors.

This case is easily treated - you need to remove the frame or the back cover of the monitor and pull out the board with buttons. Most often, there you will see a crack in the board or in the solder.

Sometimes there are faulty buttons or a loop. 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 is due to aging of the backlight lamps. According to my data, LED backlighting does not suffer from this. Deterioration of the parameters of the inverter is also possible due to aging of the constituent components.

This is often due to a bad VGA cable without an EMI suppressor - a ferrite ring. If replacing the cable does not work, then power supply interference may have entered the imaging circuits.

Usually they get rid of them schematically by using filtering capacities for power supply on the signal board. Try to replace them and write to me about the result.

This completes my wonderful rating of the TOP 10 most common LCD monitor malfunctions. Most of the breakdown data is collected from repairs of popular monitors such as Samsung, LG, BENQ, Acer, ViewSonic and Hewlett-Packard.

This rating, it seems to me, is also true for LCD TVs and laptops. What is your situation on the LCD monitor repair front? Write on the forum and in the comments.

The most common questions when disassembling LCD monitors and TVs - how to remove the frame? How do I release the latches? How to remove the plastic from the case? etc.

One of the wizards made a nice animation explaining how to disengage the latches from the chassis, so I'll leave it here - it will come in handy.

To view animation - click on the image.

Recently, monitor manufacturers are increasingly completing new monitors with external power supplies in a plastic case... I must say that this makes it easier to troubleshoot LCD monitors by replacing the power supply. But it complicates the operating mode and the repair of the power supply itself - they often overheat.

I showed how to disassemble such a body in the video below. The method is not the best, but it is fast and can be done with improvised means.