DIY laptop monitor repair

In detail: do-it-yourself laptop monitor repair from a real master for the site my.housecope.com.

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How to fix a laptop screen

A broken laptop screen is a fairly common breakdown. You may have all other components working fine, such as your hard drive, RAM, and motherboard, but the display is black. At the beginning of the article, I would like to upset those who simply broke the display of their computer and now there are only cracks all over the screen. You can't glue it back, there's nothing you can do about it.

If everything remains intact, then it is still unlikely that it will be possible to fix the laptop quickly. The matrix is responsible for the images on the display of your laptop, therefore, if you see just a black screen, then most likely the matrix will have to be replaced by contacting the service center so that you pick up this spare part specifically for your model, and this is very problematic to do, I can say from my own experience. Therefore, tune in to the fact that you will have to wait a while.

If you just observe spots or stripes on your screen, then all is not lost and fix laptop screen you can still.

And so, if you are confident in your abilities, then we proceed to the repair.

Firstly. If the laptop is plugged into a power outlet, unplug the power cord and remove the battery. Only in this case will the laptop be completely de-energized.

Secondly. We look at the bezel of the laptop screen. On the front side we find round-shaped plugs. They are barely visible and cover the screws. Pry off the plugs with something and unscrew these same screws in order to free the frame itself from the screen. When you unscrew the screws, the frame will probably still hold on to the plastic latches, they need not be damaged.

Video (click to play).

Thirdly. We unscrew the mounting screws that secure the screen, find the cable (ribbon cable) that goes to the motherboard, see if it is securely attached, whether it is damaged or can be twisted.

If the reason for the breakdown was not a train, then move on.

Fourth. Illumination lamps could break. It is necessary to remove the adhesive tape that connects the matrix to the screen lamp cable. Next, you need to disconnect the decoder panel, it is located at the very bottom of the screen. Carefully, do not break the cables, otherwise you will have to buy a new matrix. Next, pull out the filters and disconnect the wire from the lamp, which is out of order.

Before installing a new lamp, check if it is working properly, and only then fix it in place.

Fifth. The last thing that could fail is the inverter. It is located at the very bottom of the screen. It must be lifted and the wires disconnected, then a new inverter must be installed.

Now all that remains is to assemble the laptop in the reverse order, I hope that you have not scattered its parts all over the room and can easily find everything that you recently removed or disconnected.

That's all, I hope you managed to fix the laptop screen.

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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!

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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, 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 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 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 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 🙂

Objective: Learn to repair the monitor, what parts need to be replaced if the monitor breaks down

Distortion of the image on the top of the screen: lines are “knocked out”, shifted within a small range

The malfunction appears only at a vertical frequency of 100 Hz at a resolution of 1024 x 768, or at a frequency of 120 Hz at a resolution of 800 x 600.

Replacement of diodes and capacitors (1 μF x 50 V) in the gate circuit of the field-effect transistors S-correction of the raster did not give any result. Oscilloscope control of S-correction signals coming from the microcontroller and switches on field-effect transistors (open-close) showed that all elements are operational.

The reason turned out to be in the increased voltage ripple of 13 V, which is formed by the power supply for the vertical scan driver. This was due to the “loss” of the capacity of the filtering electrolytic capacitor in this circuit.

When turned on, the monitor works, but when you switch it to standby mode (turn on the power saving mode), it does not switch back to working mode (when a video signal appears)

At the same time, the green LED on the front panel is blinking, the power supply is working, the potential of the DPMF & DPMS microcontroller is low.

Replacing the synchroprocessor (TDA 4841), reset chip (KIA 7042), 12 MHz resonator and EEPROM (2408) did not give any result. Replacing the microcontroller solved this problem.

LG T717BKM ALRUEE ”(chassis CA-136)

There is no line sync (see Fig. 1). Synchronization is available only in 1024 x 768 (85 Hz) mode, and a black horizontal stripe 0.5 cm wide appears on the top of the screen. When the signal cable is disconnected, synchronization is also absent. Replacing the microcontroller, EEPROM microcircuit, filtering capacitor along the B + circuit did not give any result. After replacing capacitors C604, C605, C602 (external circuits of the synchroprocessor), synchronization was restored.

Samsung SyncMaster 797DF ”(chassis LE 17ISBB / EDC)

Monitoring the power supply showed that the rectified mains voltage is supplied to the IC601 controller, but there are no secondary voltages at its outputs. After replacing the IC601 microcircuit, the monitor's performance was restored.

Quite often in monitors of this type, the rectifier diode in the secondary circuit of the 14 V power supply fails. As a result, the MT controller switches to the protection mode and there are no secondary voltages at the unit output.

Power supply protection activates when monitor is turned on

All output voltages are greatly underestimated (within 2 ... 4 V), and the voltage at the output of the 50 V channel is 10 ... 20 V. The PWM transistor of the B + Q719 controller is very hot.

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After removing the front frame, it is necessary to disconnect the connectors of the high-voltage wires on the inverter board going to the LCD panel. We do not recommend pulling the wires in order to avoid breaking the conductors, but to remove the connectors of the high-voltage wires with special tweezers.

There are four main components of an LCD monitor:

Power supply that supplies power to the signal processing unit, LCD module and high-voltage converters (inverters)

Node of high-voltage voltage converters (inverters) of CCFL power supply of backlight lamps.

Signal processing unit. In multimedia monitors, the signal processing unit is much more complex and contains more elements.

LCD module. The structure of the LCD module is described in the article "How the LCD monitor module works"

Before starting the search for the cause of the malfunction, an initial inspection of the nodes should be performed to determine the elements with a changed shape, as well as darkening on the boards, indicating heating of the components. If a component heats up until the board material underneath darkens, this could indicate a component failure or a malfunction in the circuit to which that component belongs.

2. Stage two: Determining the cause of the malfunction

To determine the cause of the malfunction, you will need a device diagram (or a service manual), a multimeter with the functions of dialing, measuring AC and DC voltage, measuring the capacitance of capacitors, as well as an oscilloscope (to diagnose a signal processing unit, a digital oscilloscope with memory may be required)

3. Stage three: Replacing defective components

Replacing faulty components may require a soldering station with temperature control of the tip, and replacing elements of the signal processing unit - a special hot air soldering station. Note that some microcircuits are sensitive to excessive heat and may fail if overheated. Also, overheating of the pads and tracks must not be allowed, since with excessive heating, delamination and breakage of the conductor on the printed circuit board may occur. If the microcircuits in BGA and FBGA cases are malfunctioning, you may need infrared soldering equipment with an appropriate set of stencils, as well as a special flux.

4. Fourth stage: Post-repair testing

After replacing defective components, a necessary mandatory step is testing after repair. The testing phase will require an electronic thermometer, a DC voltmeter, an ammeter, and a test signal source. The minimum testing time for a restored monitor, according to statistics from practice, is not less than 12 hours.In cases of elimination of malfunctions that appear with warming up or are of an unsystematic nature, the testing time should be increased to 20-30 hours. Testing should take place under the constant supervision of a specialist.

5. Fifth stage: Assembling the monitor

Assembling the monitor should be done in the reverse order of opening. Particular attention should be paid to the screwing force and the length of the screws and self-tapping screws to be screwed in. If the screw or self-tapping screw turns out to be longer, then there is a danger of damage to the housing elements and the LCD panel.

Within the framework of one article, it is impossible to describe all the possible design features and methods of restoring monitors, and in each specific case, the path to finding the cause of the malfunction is unique. Sometimes an engineer with many years of practical experience has to strain his head to understand the design and circuitry solution.

Conclusion: In the course of practical work, I studied theoretical material, learned how to repair a monitor and learned what parts need to be replaced in case of a monitor breakdown, how to repair a monitor with my own hands.

What is laptop screen repair? This is a common replacement for the liquid crystal matrix. This procedure is elementary, and in service centers they can handle it in almost 30 minutes. True, there is one hitch: the service center may require a completely unacceptable amount for diagnostics and installation. What to do in such cases? How to fix a laptop screen without overpaying for it? To be honest, everything is so easy here that an experienced user can cope with dismantling and replacing in twenty minutes. Do you still have doubts about the location of the replacement? Can I fix my laptop screen myself? Still would!

The highest quality and best work is a work that you take with your own hands. If doubts gnaw at you or you are afraid to confuse something, then we suggest that you familiarize yourself with the step-by-step instructions for disassembling and assembling a laptop screen, after reading which you can immediately get down to business. No special technical knowledge is required here if you have ever disassembled electronic household appliances. You yourself can save your money and time, and the experience will be very useful.

We arm ourselves with a working computer with Internet access and do the following:

Open a search engine and enter your laptop model name.
The technical characteristics of the device must indicate the type of screen, its dimensions and model.
Again, not without the help of the Internet, we drive in the name and dimensions of the required display, go to any online store and order it.

The abundance of equipment in the store allows you to find the most optimal display in terms of price and quality.

To replace the matrix, you will need the following tools:

Small Phillips screwdriver. Universal models with a small number of different attachments are perfect.
A sharp object. A scalpel, a sharp knife, or a slightly sharpened pick will do a great job. But remember that objects are sharp, try to use them with extreme care.

How to fix a laptop matrix if you have all the necessary items in stock? We will not torment you. Let's start explaining the first step.

Important! Do not forget about basic safety precautions and disconnect the power to the device before starting work.

In order to dismantle the LCD screen from the front of the laptop, follow the instructions below:

Find the screws that hold the bezel. They are usually located in the corners and covered with special soft nozzles.
Get rid of the attachments, grab a Phillips screwdriver and unscrew the screws. Be sure to put them aside in a safe place so that you can easily put everything back in place.

Important! Several more screws will appear at some stages of the assembly. Try not to mix them up!

The frame can be removed without difficulty.Just remove it from the plastic latches that are located around the perimeter of the frame.

Important! It may be planted with glue or a sticky strip in some places.

Laptop models are different, but the same principle applies to all. If you have successfully removed the plastic frame, you will be able to deal with the screen itself and the inverter even faster. In this procedure, only one difficulty can arise - removing the matrix from the loops. But here, too, there are loopholes that will help avoid the risk of damaging something:

Remove the screws that hold the screen. They should be located on the back.
Now remove the hinges that secure the die.

Important! Do not make great efforts when dismantling the matrix, otherwise you risk putting some component out of order.

The next step is to disconnect the VGA cable from the back of the display.

Important! Removing the plume should be done with extreme caution.

Most often, the train is held on a piece of tape, which is located on the back of the matrix. It is enough to gently pull down on the cable to disconnect it.

Important! Some models are equipped with special latches that prevent it from “falling off”.

Now you need to dismantle the broken matrix: just unscrew the screws that hold it and remove it. Take your time to handle the inverter cable.

How to repair laptop screen next? There is very little left!

The vast majority of displays are equipped with an inverter cable, which is located directly below the screen. Especially often this arrangement is relevant for older laptop models.

Important! The inverter board is a long printed circuit board to which a pink or black cable connects. This is the inverter cable.

To remove it, you need to pull a little on it. When assembling, you will definitely not be mistaken with the correct installation of the cable, since it can only be connected with the correct side.

If you have coped with all the previous stages one or two times, then installing a new matrix will seem like a trifling matter for you. Just follow the same procedure step by step, only in reverse order. But there is one nuance here - you will have to be even more careful with the new matrix, do not rush to install it.

And so we have a faulty matrix, no matter how we made this diagnosis, let's say this is so.

The most common problem associated with matrices is its mechanical damage, that is, breakage, if this is the case, then the matrix can only be replaced, it can no longer be repaired.

If the matrix is not broken, then you can still try to repair it, this will be our article today, namely, repairing a laptop matrix with your own hands.

First, we need to decide what class the matrix is in the laptop.

Matrices are divided into two broad camps:
- Lamp matrices (no longer produced but very widespread in laptops of the previous generation)
- LED matrices (that is, those that are used now).

In tube matrices, the principle of operation, of course, is the backlighting of the screen with lamps using an inverter, which is usually placed outside the matrix.

In LED, the principle is simpler, LED. LEDs are used as screen backlight.

In this article, we will not consider how to repair a laptop inverter with our own hands, we will talk about this sometime next time. In this article, we are talking specifically about repairing a laptop matrix on our own.

And so we dismantled the matrix from the cover, turn it over, and what we see is a board on which there are many different SMD components.

We remove the film of the insulating board and start ringing the power supply of your matrix, in fact, this can be done from the socket, by the dialing method. To find out the resistance of each contact, we will use the pinout datasheet.

Found a broken chain? Great, we find out from the datasheet what it is responsible for and change the element to which it belongs.

When soldering on a matrix, the main thing to take into account is the temperature. Solder with Rose or Wood alloys at temperatures no higher than 150 degrees. the plastic behind the board can melt, and in general the temperature can damage the device.

If all the elements on the board are okay, you should check the lighting sources, if everything is simple with the LEDs, apply the power source to the LED strip and everything will immediately become clear, then you need to work with the lamps through an inverter since the voltage on the lamps is about 1000 Volts!

Video (click to play).

Do not be alarmed, it is not dangerous because the current is weak, if the inverter does not supply power to the matrix lamps, then problems need to be looked for from it, but we will talk about repairing the inverter in future articles, in this one we examined how you can repair a laptop matrix with your own hands. If you are not confident in your abilities, then it is better to contact the specialists of our service center Devpoint Hardware.

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