The acceptable number of defective pixels on an LCD monitor. Check your monitor before purchasing. The best monitor tests online Checking the LCD display
In some cases, we need to check the monitor for functionality online. This could be buying a used device or identifying the causes of the malfunction. A few years ago, this required taking your monitor to a workshop; there were no other options. Today you can test the monitor yourself online in your browser. To do this, you just need to go to the desired page, select the type of verification and activate the service. In this article, I will talk about several of the best sites that can accurately diagnose your monitor.
Online Monitor Test - check with the help of a tester
The Online Monitor Test service is an English-language online monitor tester that has several testing options.
Each of these options will use the same monitor checking algorithm; choosing any of these three methods does not affect the final result. The first to automatically run is a test of your monitor’s ability to reproduce colors that are similar in shade. Monitors with high-quality display of shades are able to distinguish between dark tones a difference of two percent. To display other tests on this service, move your mouse cursors to the top of the screen. A menu will appear where you can test the monitor in different ways.
For those who work with multiple monitors at the same time, a special test “Input Lag Html” will be useful, which displays the delay of information output on another monitor.
Monteon - testing a computer display
With the Monteon test you can test not only your computer monitor, but also mobile device. To do this you just need to type in address bar website address Monteon.ru and run an online monitor test. This service has the great advantage of a Russian-language interface. If you need a specific test, e.g. defective pixels– simply run the test by clicking “Start”. If it is needed detailed description each test, click “Learn more about tests.”
Main page of the Monteon service
It is recommended to do tests indoors without sunlight and with minimal lighting for better perception of events on the monitor. The service will offer you, go to nago. To make the test management menu appear at the bottom of the screen, move the mouse. The test menu allows you to scroll through unnecessary tests, flip (if the test allows it), turn off full screen mode and return to the start screen. Along the edges of the monitor are arrows for moving from one test to another. You can replace the arrows used by the mouse with keyboard arrows. Their actions are equivalent. Also, for the test, it is recommended to disable all programs that correct color rendering on the display. They could be drivers for the video card. Go to the settings of this program and deactivate it for the duration of the test.
The following tests are available on the Monteon service:
Only some of the tests that are available to users on this service. To get acquainted with full list tests, go to the website and open the “Learn more about tests” section.
Catlair - monitor diagnostics in the browser
On the web page https://catlair.ru/?body=TestMonitorWhite you can test your monitor by selecting the appropriate one from the list. Available on the website:
Here are the TOP 10 most common malfunctions of LCD monitors that I have personally experienced. The rating of malfunctions is compiled according to the personal opinion of the author, based on experience in service center. You can take this as a universal repair manual for almost any LCD monitor from Samsung, LG, BENQ, HP, Acer and others. Here we go.
I divided the malfunctions of LCD monitors into 10 points, but this does not mean that there are only 10 of them - there are many more of them, including combined and floating ones. Many of the breakdowns of LCD monitors can be repaired with your own hands and at home.
1st place – monitor does not turn on
at all, although the power light may blink. In this case, the monitor lights up for a second and goes out, turns on and turns off immediately. Jerking the cable, dancing with a tambourine and other pranks do not help. The method of tapping the monitor with a nervous hand usually doesn’t help either, so don’t even try. The reason for this malfunction of LCD monitors is most often the failure of the power supply board, if it is built into the monitor.
Recently, monitors with an external power supply have become fashionable. This is good because the user can simply change the power source in case of breakdown. If there is no external power source, you will have to disassemble the monitor and look for a fault on the board. in most cases it is not difficult, but you need to remember about safety precautions.
Before fixing the poor guy, let him stand for 10 minutes, unplugged. During this time, the high-voltage capacitor will have time to discharge. ATTENTION! It is DANGEROUS TO LIFE if the PWM transistor also burns out! In this case, the high-voltage capacitor will not discharge in an acceptable time.
Therefore, EVERYONE check the voltage on it before repairing! If dangerous voltage remains, then you need to discharge the capacitor manually through an insulated one of about 10 kOhm for 10 seconds. If you suddenly decide to short-circuit the leads, then protect your eyes from sparks!
Next, we proceed to inspect the monitor’s power supply board and replace all burnt parts - these are usually swollen capacitors, blown fuses, transistors and other elements. It is also MANDATORY to solder the board or at least inspect the soldering under a microscope for microcracks.
From my own experience I will say that if the monitor is more than 2 years old, then 90% there will be microcracks in the soldering, especially for LG, BenQ, Acer and Samsung monitors. The cheaper the monitor, the worse it is made at the factory. To the extent that the active flux is not washed away - which leads to failure of the monitor after a year or two. Yes, yes, just when the warranty ends.
2nd place - the image blinks or goes out
when you turn on the monitor. This miracle directly indicates to us that the power supply is faulty.
Of course, the first thing you need to do is check the power and signal cables - they must be securely fastened in the connectors. A flickering image on the monitor tells us that the monitor's backlight voltage source is constantly jumping out of operating mode.
3rd place - turns off spontaneously
after the time has elapsed or does not turn on immediately. In this case, again, there are three common malfunctions of LCD monitors in order of frequency of occurrence - swollen electrolytes, microcracks in the board, faulty microcircuit.
With this malfunction, a high-frequency squeak from the backlight transformer can also be heard. It typically operates at frequencies between 30 and 150 kHz. If its operating mode is disrupted, vibrations can occur in the audible frequency range.
4th place - no backlight,
but the image is visible under bright light. This immediately tells us that LCD monitors are faulty in terms of backlighting. In terms of frequency of occurrence, it could be placed in third place, but it is already taken.
There are two options - either the power supply and inverter board burned out, or the backlight lamps are faulty. The last reason is not common in modern monitors. If the LEDs in the backlight fail, then only in groups.
In this case, the image may darken in places at the edges of the monitor. It is better to start repairs by diagnosing the power supply and inverter. The inverter is that part of the board that is responsible for generating a high-voltage voltage of about 1000 Volts to power the lamps, so under no circumstances should you try to repair the monitor under voltage. You can read about it on my blog.
Most monitors are similar in design, so there shouldn't be any problems. At one time, monitors simply fell off due to poor contact near the tip of the backlight. This can be cured by carefully disassembling the matrix in order to get to the end of the lamp and solder the high-voltage wiring.
A simpler way out of this unpleasant situation can be found if your friend-brother-matchmaker has the same monitor lying around, but with faulty electronics. It won’t be difficult to make two monitors of similar series and the same diagonal.
Sometimes even the power supply from a monitor with a larger diagonal can be adapted for a monitor with a smaller diagonal, but such experiments are risky and I do not recommend starting a fire at home. But in someone else’s villa, that’s a different matter...
6th place - spots or horizontal stripes
Their presence means that the day before you or your relatives had a fight with the monitor over something outrageous.
Unfortunately, household LCD monitors are not equipped with shockproof coatings, and anyone can offend the weak. Yes, any decent poke with a sharp or blunt object will make you regret it.
Even if there is a small trace or even one broken pixel left, the stain will still begin to grow over time under the influence of temperature and voltage applied to the liquid crystals. Unfortunately, it is not possible to restore dead monitor pixels.
7th place - no image, but backlight is present
That is, a white or gray screen appears on your face. First, you should check the cables and try connecting the monitor to another video source. Also check whether the monitor menu is displayed on the screen.
If everything remains the same, look carefully at the power supply board. The power supply of an LCD monitor usually generates voltages of 24, 12, 5, 3.3 and 2.5 Volts. You need to use a voltmeter to check if everything is okay with them.
If everything is in order, then carefully look at the video signal processing board - it is usually smaller than the power supply board. It contains a microcontroller and auxiliary elements. You need to check if they are getting food. Touch the contact of the common wire with one (usually along the outline of the board), and with the other, walk along the pins of the microcircuits. Usually the food is somewhere in the corner.
If everything is in order regarding the power supply, but there is no oscilloscope, then we check all the monitor cables. On their contacts. If you find something, clean it with isopropyl alcohol. In extreme cases, you can clean it with a needle or scalpel. Also check the board with the monitor control buttons.
If all else fails, then perhaps you are faced with a case of broken firmware or microcontroller failure. This usually happens from surges in the 220 V network or simply from aging of the elements. Usually in such cases you have to study special forums, but it’s easier to use them for spare parts, especially if you know a familiar karateka who fights against unwanted LCD monitors.
8th place – does not respond to control buttons
This case can be easily treated - you need to remove the frame or back cover monitor and pull out the board. Most often there you will see a crack in the board or in the solder.
Sometimes there are faulty or . A crack in the board violates the integrity of the conductors, so they need to be cleaned and soldered, and the board must be glued to strengthen the structure.
9th place - reduced monitor brightness
This occurs due to aging of the backlight bulbs. LED lights According to my data, it does not suffer from this. It is also possible that the parameters of the inverter may deteriorate, again due to the aging of the components.
10th place - noise, moire and image jitter
This often happens due to a bad VGA cable without an EMI suppressor -. If replacing the cable does not help, then it is possible that power interference has penetrated into the imaging circuits.
Usually they are eliminated from the circuit design by using filter capacitors for power supply on the signal board. Try replacing them and write to me about the result.
This concludes my wonderful rating of the TOP 10 most common malfunctions of LCD monitors. The bulk of data on breakdowns was collected based on repairs of such popular monitors as Samsung, LG, BENQ, Acer, ViewSonic and Hewlett-Packard.
This rating, it seems to me, is also valid for and. What is your situation on the LCD monitor repair front? Write to and in the comments.
Sincerely, Master Pike.
P.S.: How to disassemble the monitor and TV (how to snap off the frame)
The most FAQ when disassembling LCD monitors and TVs - how to remove the frame? How to release the latches? How to remove the plastic case? etc.
One of the masters made good animation, explaining how to remove the latches from engagement with the body, so I’ll leave it here - it will come in handy.
To view animation— click on the image.
Instructions
Look at the monitor. If the brightness of the screen has sharply decreased (usually on one side) or the image on the monitor has acquired a pink tint, then the cause of the malfunction is the lamp, which illuminates the image from below.
Leave it to professionals to check if the monitor backlight is faulty, as all the parts are of a rather fragile design. You can damage the matrix with a careless movement. If you decide to check the lamp yourself, be extremely careful. The cable connecting the lamp to the matrix is high voltage (1000 volts).
Before starting to check the serviceability of the lamps, prepare workplace: It must be free of dust. Penetration of dirt and dust onto the matrix is unacceptable.
Check the connection of the cable leading to motherboard, with a monitor. Unscrew the monitor frame, which is secured with screws under the rubber plugs. The connection must be made properly.
Make sure that it is the backlight lamp that is faulty. To do this, connect a lamp that is known to work or connect the matrix to a working backlight module.
Remove protective film, which closes the board. Do this very carefully, preferably using a scalpel or tweezers. The matrix is a very thin plate with conductors that cannot be restored if damaged.
Take out the matrix, light filters, and then a pencil case with lamps, which are mounted in twos in the pencil case. A burnt-out lamp will show black wide rings near the cathodes. Be careful not to break the lamp: its fragments can damage the filters and reflectors.
Try to remove the lamp from the pencil case using light force. When the resource is exhausted, the lamp begins to get very hot. So much so that, due to heating, the cathodes can even melt and stick to the matrix. The temperature of the device or the presence of melted fragments of the housing can also be used to judge the serviceability of the lamp.
Video on the topic
High-quality and timely testing of backlight lamps in LCD panels can significantly reduce the time spent on repairs, since the malfunction or serviceability of the lamps is detected even before disassembling the panel. In order to carry out quick and reliable diagnostics, use a device specially designed for this, and we will tell you how it works.
Instructions
To check the backlights on LCD panels, use a device specially designed for this purpose. This device allows you to carry out quick check backlight lamps, without requiring their removal and disconnecting the cables from the inverter.
Before you start using the device, be sure to turn off the device being tested. Using this device, you get a complete and accurate diagnosis of all lamps, and this allows you to identify faulty lamps even before disassembling the panel, or understand that all lamps are working and the converter needs to be replaced. This method makes repair time significantly shorter and also reduces risk possible damage during diagnosis.
In order to carry out competent diagnostics using such a device, follow the following instructions.
Before starting diagnostics, turn off the device being tested from the network. Paste network adapter into the desired socket and plug it into a power outlet. The device will be in standby mode and two LEDs will be on.
Determine the position of the board in the device under test, as well as the cables that connect the inverter to the backlight lamps. Connect the wire to the one being tested. This point is very important for the verification process, so make sure that there is no possibility of accidental disconnection of the wire.
Now take the device in your hands and touch its tip to the place where the lamp is connected, fix the tip firmly, do not allow it to move, as high voltage may damage the inverter. Next, press the large button (the one closest to the tip).
Please note that the indicator light should go out at this time and not remain on while the button is pressed. Literally a second later you can start reading the readings: - one LED went out while the button was pressed, and then the other one turned on - the lamp is working
- one LED did not go off while the button was pressed, and the other did not turn on - the lamp is faulty.
After the test, release the button; the LEDs should light up, as the device will be in standby mode.
Video on the topic
There are many devices equipped with LCD screens without backlight. Using them in the twilight is inconvenient, and in the dark it is completely impossible. You can correct this drawback by adding backlighting yourself.
Instructions
Turn off the power to the device. Remove the batteries from it (devices without backlight are usually powered by them, and not by batteries). In this case, you will have to accept the possible loss of data or do it in advance, before removing the batteries. backup copy.
Be sure to ensure that the batteries have enough capacity to keep the backlight operating for an extended period. If this is not the case, install an additional compartment to accommodate the backlight batteries (including externally).
If the device uses a liquid crystal indicator of a collapsible design, pressed to the board through rubber contact combs, evenly unscrew all the fastening screws and remove the LCD. Peel off the silver backing. Reassemble everything exactly as it was, without forgetting a single part, including the contact combs. During the assembly process, place a thin plexiglass plate between the board and the indicator, coated on both sides with a thin layer of white paint that transmits light well. This plate, after assembly, should move freely under the indicator without exerting the slightest pressure on it. Also tighten the screws evenly during assembly.
Then take two SMD LEDs of the desired color. Glue them to the plate from the end on the side to which there is access. Connect a resistor in series with each of them so that at the voltage they will be powered by, the current through each of them does not exceed 3 mA. The wires must be very flexible. Connect these chains in parallel and connect to a power source in the correct polarity through the device's power switch, or the latter is powered directly from the batteries through a separate, pre-installed miniature switch. If the backlight is powered by separate batteries, it will need its own source in any case.
In a situation where the device uses a non-separable indicator, proceed in a different way. Place two SMD LEDs connected in the same way outside. Cover them with a small opaque screen that does not allow light to pass forward, and point the diodes themselves at the indicator so that they illuminate it fairly evenly. Secure them in this position.
Reinstall the batteries. If necessary, install additional lighting elements. Re-enter the data: if it is a clock, then the time and date, if it is programmable, then programs and variables, and if it is an electronic notepad, then names and phone numbers.
Video on the topic
Sources:
- DIY instrument panel lighting for VAZ 2106
Replacing the monitor backlight is a rather labor-intensive process that requires you to be attentive and extremely careful. Remember that if you do not follow the basic rules, you can completely ruin the matrix.
