DIY viewsonic monitor repair

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 LCD type of monitors (Liquid Crystal Display - display on the basis of liquid crystals) 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 widespread 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, it was necessary 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 like 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 is the problem? 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, chick 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 the processor board, and on the right, the power board combined with the 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 form 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 in 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 1000 microfarad capacitors, I put an additional 330 mF element 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 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. I 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 higher voltage, for example, the cheapest and most reliable ones are Rubycon 1000 uF 25 V capacitors and Nippon 1500 uF 10 V capacitors.There is a cheaper of the decent (but always 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, three frequent LCD monitors malfunctions 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 by 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. It is necessary to check whether 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.

Faced a problem - the ViewSonic VA1912w monitor went out, after a while it lit up, worked for several days, and then was blown away for good. There were no ready-made recipes on the network, but there are a lot of questions with exactly the same symptoms. Therefore, in hot pursuit, I am writing a recipe. Who needs it - write it down. The instruction is not step-by-step, and is designed for people who know how to work with a soldering iron and, most importantly, with a head. 🙂

Monitor: ViewSonic VA1912w (typical circuit, so the recipe will be useful to many others).
Malfunction: When connected to the network, the LED on the panel briefly lights up (or does not light up at all), and then goes out.The screen does not light up, there are no signs of life.
Malfunction symptoms: The TSUM17AK-LF-1 chip is heating up, electrolytic capacitors in the power supply may be swollen.
Supply voltages: + 5V is normal, + 12V is down.

General view of the disassembled monitor:

Click on the image to enlarge

1. Replace the 4 electrolytic capacitors shown in the next photo. It is we replace, and not “solder and measure”. 2 pieces - 220.0x25 and 2 pieces - 1000.0x25. If, in addition to these, there are bloated ones, we mercilessly change.

2. Trying to turn it on. If the monitor is working, you are already fine, collect it. If not, we continue. I want to remind you that you cannot turn on the monitor for a long time, since our TSUM17AK-LF-1 chip boils pretty well, and we risk completely ruining the monitor if we burn it.

3. We find the transistor Q8 on the next board next to the quartz resonator and measure the voltage on its collector, it should be + 1.8V. We make sure that everything is there, but not 1.8.

4. Carefully solder Q8 and in its place we solder the good old KT835 from the domestic electronic past, or any other silicon direct conduction transistor. I even ran it with KT361, but did not dare to leave it - you never know ... Yes, I strongly recommend choosing a leak-free transistor.

Click on the image to enlarge

After replacement, there is a 99% chance that your monitor will work. Of course, there may be nuances, but with such symptoms (and they are typical for these monitors), start diagnostics with these details.

Well, for lovers of techno-macro landscapes - a photograph of our transistor KT835, saving foreign infirmities ... 🙂

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 look like ordinary fluorescent lamps, but in contrast to them, they are much smaller. 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 be turned 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 a capacitor rating, 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.

Similarly, 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. Happy repairs to everyone! Especially for Radioskot.ru - AKV.

In most cases, the reason that the monitor does not turn on or there are problems with the image is the incorrect operation of the video card, incorrect settings or incorrect connection.

1. Disconnect all wires from the monitor
2. Connect only power cable
3. The monitor should turn on. The message "No signal" appears on the screen
   After a while, the monitor enters the “Stand by” power saving mode (the power indicator changes color, the picture disappears)

Screensaver when the monitor cable is disconnected

In this case, the monitor is most likely good. There are, of course, possible exceptions.

You can also check the health of the monitor by connecting it to another computer.

If the monitor has proven to be inoperative, it is worth contacting a service for diagnostics and repair. Our article will tell you what to look for when describing the problem, so that already during a telephone conversation you will be correctly guided in terms of price and repair time.

Before calling a workshop, find out the exact name of your monitor model. A number of models have standard malfunctions that have long been known to service center employees.

Monitor does not turn on, power indicator is off

If the monitor shows no signs of life, there is likely a power problem. Most often, this breakdown is easily repaired.

There might be a problem with the monitor's power cable or connectors. In this case, if you change the position of the power cord, the indicator may light up briefly when the contact appears. In case of complete inoperability, it is likely that the power supply will need to be repaired.

Power light is blinking, no picture

Blinking of the voltage indicator (cyclic power on / off) regardless of the position of the cord is a signal of incorrect operation of the power supply or the main board (main board).

The service center will determine the cause of the problem and fix it.

Power indicator is on - no image, backlight is on

The most likely problem is the processor board (MB) of the monitor. For diagnostics, you will have to contact the service, since such "symptoms" do not allow you to immediately determine the cause of the malfunction. The master will be able to give the exact answer only after examining the disassembled monitor.

Inside of the monitor with lamp backlight

The backlight of the monitor does not come on or goes out after a few minutes of operation

Sometimes the picture can be seen in reflected light, when looking at the monitor from above, from the side. The monitor reacts to buttons, there is access to the menu. It is possible that the monitor works immediately after switching on, and after a few minutes the backlight turns off. The problem is in the inverter or in the backlight lamps: they burn out over time or can suddenly fail as a result of mechanical stress (for example, shock). Repair consists in replacing lamps or a converter.For this procedure, it is worth choosing a service meticulously: the procedure is complex, requiring a certain level of qualifications and increased accuracy from the master.

Decreases screen brightness and appears reddish

These symptoms indicate burnout of the backlight lamps, as in the previous case. There may be a drop in brightness and a reddish tinge only in a specific area of ​​the screen or across the entire monitor. The problem is solved by replacing the lamps, and as a preventive measure, various dark screensavers and monitor sleep mode settings are used. The fewer nights the monitor will stand with a static image on, the longer the lamps will last.

The appearance of vertical or horizontal stripes on the monitor screen is a sign of a malfunction of the decoder loops. If the stripes change their location, then the problem may be in the video card, and if the stripes have constant localization and colors (black, white, colored), then the problem is in the monitor matrix. The masters in service centers practically do not undertake to replace the loops, since there is no confidence in the success of the operation and that the problems will not return in a short time. The only solution to the problem is to replace the matrix assembly. If your monitor is under warranty, immediately after the stripes appear, contact the service, even if there is only one stripe so far and it does not bother you.

If the stripes appear on the monitor, the warranty period of which has already expired, find out at the service center the cost and the estimated repair time for your model. An original matrix is ​​required, and the cost can be comparable to buying a new monitor.

Red bar on the screen

Distorted image or color

Usually occurs due to the loss of contact in the signal cable or broken connectors. Check the signal cable (VGA, DVI) by replacing it.

The DVI (digital) cable can only be switched (.) On a power-down monitor.

If the defect persists, then this is most often due to either incorrect operation of the video card, or a breakdown of the monitor processor board. In some cases, it can be fixed by flashing.

The master will be able to name the exact cause of the malfunction and the cost of repair only after diagnostics.

The monitor does not display an image from the computer, displays messages

If, instead of the usual picture, the monitor displays a service message ("check the cable" or "non-optimal mode"), and this state does not change after the appropriate changes (replacing the cable, setting the required mode), most likely the problem is in the monitor. A number of monitor models with a MICOM processor (Samsung 710 (N / V), 713/913, some Philips, LG) have a standard malfunction associated with a rapid failure of the processor. Repairing or replacing the defective processor will completely fix the problem.

LED monitors differ in the type of backlighting: LEDs are used instead of lamps. Breakage of LEDs, which manifests itself as a decrease in brightness in a separate area of ​​the screen, is quite rare and is successfully repaired.

We draw your attention to the fact that a slight unevenness of the backlighting of an LED monitor in budget models is already encountered upon purchase. In this case, the center of the screen is more illuminated than the edges. This is due to the use of cheap materials to create the scattering layers of the screen. Not perfect color reproduction is also a feature of LED monitors, they are simply not designed for professional color work.

One of the frequent breakdowns of LED monitors is screen flickering, which becomes noticeable when the brightness decreases. For some models, repairs are limited to flashing, while others require replacement of the processor board.

The interior of the monitor with LED backlight