LCD monitors are made up of many complex components, so it is not unusual for them to malfunction or fail. For most problems, excluding severe structural damage, an easy solution can be found directly within the walls of the house. Read the article and do not miss the section dedicated to safety advice because some repairs could expose you to the risk of coming into contact with strong electric current discharges.
Steps
Part 1 of 3: Diagnosing the Problem
Step 1. Check the warranty
Most new devices are sold with a warranty of at least one year. If your monitor's warranty is still valid, contact the manufacturer to have it repaired for free or to benefit from a reduction in repair costs. Remember that in these cases trying to repair the damage yourself will invalidate the warranty.
Step 2. Check the lights
If the monitor no longer displays any image, turn it on and check the status lights on either side of the device. If one or more of the LEDs present are illuminated, continue reading the next step. If all the lights remain off, the power supply or one of the power cords may have a problem. Normally such a malfunction is caused by a blown capacitor. You can try to fix the problem yourself, in which case remember that the circuit that manages the power supply of an LCD monitor includes high voltage and therefore very dangerous components. Unless you are an electrician experienced in such repairs, take your monitor to a professional repair center.
- Other signs that may indicate the presence of a blown capacitor include a loud hum, lines across the screen, and multiple image display.
- The power supply unit of an LCD monitor is one of the most expensive components. If the problem were to be more complex than a simple blown capacitor, the cost of repairs could be considerable. If many years of honorable service already weighs on your monitor's shoulders, it may be advisable to replace it with a new one.
Step 3. Light up the monitor screen with a flashlight
If the LCD panel stays off, but the power light turns on, try this. If, by illuminating the screen with a flashlight, you are able to see the image, it means that the problem lies in the backlight system of the device. Follow this procedure to replace any defective lamps that illuminate the monitor's LCD panel.
Step 4. Repair a stuck pixel
If your LCD panel is working fine, but you notice a few individual pixels that are "stuck" to a specific color, then they can usually be repaired easily. Turn on the monitor and follow these instructions:
- Wrap the tip of a pencil (or other object with a blunt, thin tip) in a damp, non-abrasive cloth. Rub it very gently on the defective pixel. Applying too much force will risk aggravating the damage.
- Search online for stuck pixel repair software. These programs send a quick sequence of different colors to the LCD panel that can restore the correct functioning of the defective pixels.
- Purchase a component specially designed to connect to LCD monitors and repair damaged pixels.
- If none of the recommendations listed work, you may be forced to change your monitor's LCD panel to fix the problem.
Step 5. Try to repair the screen cracks or dull areas
These clear signs of physical damage often indicate a monitor that is no longer repairable. If you persist in trying, you could do even more damage. However, if a reduced monitor in this state is in no way usable, attempting to repair it before purchasing a new one will certainly not aggravate the situation:
- Swipe the surface of the screen with a soft cloth. If you notice the presence of breaks in the glass layer, do not proceed further with the repair. Just buy a new monitor.
- Rub the scratch with a clean eraser; do it as gently as possible. Carefully remove any gum residue that has accumulated on the screen.
- Purchase a scratched LCD panel repair kit.
- Read this article to get an overview of possible home solutions.
Step 6. Purchase a replacement LCD panel
If you are using an external monitor, consider purchasing a new one. This solution may be cheaper than installing a new component on an old monitor, the lifespan of which may be limited. However, if the damage is to a relatively new laptop or device, considering replacing the LCD panel or display might be a good solution. To carry out the installation, ask for the intervention of a professional.
- The serial number of the LCD panel is usually printed directly on the back of the device. Use this code to order the replacement part directly from the manufacturer.
- While it is possible to try to replace an LCD panel yourself, it is a very complex process that exposes you to the risk of coming into contact with strong electrical shocks. Follow the assembly guide dedicated to the specific monitor model in your possession, in this way you will maximize the safety and the chances of success of the repair.
Step 7. Perform other checks
There are many reasons why an LCD monitor may malfunction, the steps shown here are useful in diagnosing the most common problems and causes. Before proceeding further, put into practice the advice given to check if your problem falls within the cases described. If the damage is not found or if the suggested repair does not work, also consider the following issues:
- If the panel responds to the input signal, but the image is blurred, such as displaying a cluttered set of multicolored squares, the AV (audio video) card may be damaged. The AV card is the rectangular shaped printed circuit board that is normally found near the audio and video inputs of the monitor. Replace any components that appear clearly damaged using a dedicated soldering iron, or change the entire board by installing the new one very carefully, securing it in the appropriate seat, and connecting all cables correctly.
- The main control buttons may be defective. Carefully clean the relevant metal contacts using a suitable product or, in the case of loose or out of place buttons, restore correct operation. If necessary, access the printed circuit board on which they are attached directly and check that the connection cables and soldering are in perfect condition, if not, repair the damage using a soldering iron.
- Check the connecting cables to make sure they are not damaged. If you can, try using another set of cables. Again, inspect the circuit board to which they are connected directly and verify that the solders are in perfect condition, if not, repair the damage using a soldering iron.
Part 2 of 3: Replace a Burnt Capacitor
Step 1. Understand the dangers you face
Capacitors can hold their charge even after the power supply has been removed. Handling them improperly could expose your body to dangerous, sometimes even fatal, electric shocks. Take the following precautions to protect yourself and your device from possible damage:
- Be honest in evaluating your technical skills. If you have never replaced an electrical component of this type or are inexperienced in handling electronic circuits, ask a professional for help. Performing this type of repair is not suitable for inexperienced people.
- Wear an anti-static wristband and work in a static-free environment. Keep the work environment free from wool, metal, paper, gauze, dust, children and pets.
- Avoid working in areas that are too dry or too humid. The ideal humidity level should be between 35 and 50%.
- Before starting to work, unload your body on the ground. To do this, touch a metal part of the monitor frame while the device is off, but still connected to the mains.
- Work while standing on a surface with a low level of friction. If there is a rug under your feet, treat it with a product that eliminates static electricity before you begin.
- Wear tight rubber gloves. This way you will be able to handle components and tools with precision and agility.
Step 2. Disconnect the power
If your monitor is an integral part of a laptop or other battery-powered device, unplug it before you begin. Such a measure reduces the chances of receiving an electric shock.
- Even if the device has a built-in battery, therefore "non-removable", once you open the external structure, normally, you will be able to disconnect it. Enter the web and look for a guide that explains how to disassemble your specific model, follow the instructions indicated.
- Some of the components in your computer will continue to hold their electrical charge. So be very careful and don't touch any element before you have identified it.
Step 3. Keep track of all the operations you perform
Work on a large, clean, flat surface after clearing it of all the items you don't need. Use a series of small containers in which to insert the fixing screws and any other components as you go to remove them. Label each of the containers with the name of the element they were used to fix or with the sequence number of the step it refers to.
Before disconnecting any internal cables or connections, you can opt to photograph the monitor. This way you will have an additional reference that will be useful to you in the reassembly phase
Step 4. Remove the outer cover
To do this, unscrew any visible screws or plastic fasteners that hold the rear cover and the front of the monitor together. To separate the two parts of the structure, using a thin and flexible tool to pry. A plastic spatula is ideal.
Performing this operation with a metal lever runs the risk of damaging an element of the structure or causing an electrical short circuit. During this initial step, using metal tools is still relatively safe, but for the next steps it is better to opt for plastic tools
Step 5. Locate the electronic board dedicated to the power supply
This section is usually located near the power cable or connector. To be able to locate this component, it may be necessary to remove additional panels. This type of electrical circuit is characterized by a series of cylindrical capacitors of various sizes, including some very large ones. Being on the non-visible side of the circuit, they will nevertheless be exposed to view only when you finish separating the board in question from the rest of the structure.
- If you are unsure which card is dedicated to controlling your monitor's power supply, search the web using the specific model of your device.
- Do not touch any of the metal contacts on this board as the capacitors may still be charged and you may run the risk of electric shock.
Step 6. Remove the circuit board
Unscrew all screws holding it in place and disconnect any ribbon cables present. When disconnecting these types of cables, always pull the connector out of its housing. In the case of horizontal or vertical sockets, apply force following their orientation. If you try to disconnect the ribbon cable by simply pulling it, you risk damaging it.
Some ribbon cable connectors have a small safety tab that must be lifted before the cable can be disconnected
Step 7. Locate and discharge the larger capacitors
Lift the card very carefully, holding it by the sides and being careful not to touch any electronic component or metal contact. Looking at the other side of the circuit board, locate the cylindrical capacitors. Each of these components is connected to the printed circuit through two metal pins. To reduce the risk of receiving an electric shock, discharge each capacitor by following this procedure:
- Buy a resistor that has an electrical resistance between 1.8 and 2.2 kΩ, with a power of 5-10 watts. Using this tool is much safer than using a simple screwdriver which could spark or ruin the integrated circuit.
- Wear rubber gloves.
- Find the larger contacts on the capacitor. Touch the two metal contacts of the capacitor with those of the resistor for a few seconds.
- To be sure of the result, check the voltage between the two capacitor contacts using a multimeter. If there is still a residual charge, connect the resistor to the capacitor again.
- Repeat this procedure with all larger capacitors on the IC. Smaller capacitors are usually unable to cause serious damage.
Step 8. Locate and photograph any broken capacitors
Look at the capacitors for any that, instead of having a perfectly flat top, have a bulge in the shape of a dome. Check each condenser for liquid leaks or any traces of previous leaks that have dried up. Before removing, photograph each element or make a note of the location and highlight it with a marker. Since these are components with a precise operating polarity, it is very important to identify the negative and positive terminal of each capacitor. If you need to replace more than one capacitor, keep track of the type and location of each.
- If none of the capacitors on the circuit appear damaged, check the electrical resistance of each using a multimeter.
- Some capacitors, instead of having a cylindrical shape, appear as small discs. This model of capacitors break very rarely, but to make sure they work perfectly, check them anyway.
Step 9. Desolder the capacitors that need to be replaced
Use a soldering iron and desoldering pump to pry the metal terminals of the broken capacitors off the circuit board. Set aside and keep the removed components.
Step 10. Purchase replacement components
Any electronics store can sell you new capacitors at really cheap prices. Look for capacitors that have the same attributes as the ones to replace:
- Dimension
- Operating voltage (measured in Volts)
- Capacitance (measured in Farads or µF)
Step 11. Solder the new capacitors
To install the new capacitors on the PCB, use a soldering iron. Make sure to connect them respecting the polarity indicated on the card. When finished, check that all new welds are solid.
- Use a soldering material that is suitable for electronic components.
- If you have lost the exact location of a particular capacitor, search online for the wiring diagram for your monitor's printed circuit board.
Step 12. Reassemble the monitor and run a test
Reassemble all connections, panels, screws and components exactly as they originally were. After installing all electrical parts and connections, and before reinstalling the rear screen cover, it is best to perform a function test. If the problem persists, you can choose to seek professional help or purchase a new monitor.
Part 3 of 3: Replace the Backlight Lamp
Step 1. Disconnect the power
For an external monitor, unplug the power cord from the electrical outlet, for a laptop, remove the battery instead.
Step 2. Disassemble the monitor
Unscrew the screws securing the rear monitor cover in place. Very carefully remove it using a plastic spatula to pry. Disconnect all components from the LCD panel, noting where each is located.
Step 3. Locate the lamp responsible for the backlight
This is a neon lamp normally placed just behind the LCD panel. In order to locate and remove it, you will need to remove any additional panels or covers. Perform each movement very gently.
Some components may still have a residual electrical charge. During the search, do not touch any printed circuit boards, except wearing a pair of rubber gloves
Step 4. Purchase an identical lamp at an electronics store
If you don't know which lamp model to buy, take a picture of the component and show it to the store staff. Also take note of the model and size of the monitor and the size of the lamp.
Step 5. Uninstall the old, or old, neon and install the new ones
Be very careful if it is a cold cathode fluorescent lamp (CCFL). This type of neon contains mercury and requires a specific disposal procedure. In this case, always follow the regulations in force in the area where you reside.
Step 6. Try performing additional repairs
If after replacing the lamp, the monitor still does not turn on, the problem may lie with the backlight power board. This circuit is called an "inverter" and is normally located near the neon lamps and has a kind of "plug" for each set of lights. Order a replacement card and very carefully install it in the monitor. To get the best result without taking any risks, follow the mounting instructions in the guide for the specific model of your monitor.
Before replacing the card that controls the backlight, make sure your monitor produces a visible image when you light it with a flashlight. If after the replacement the monitor no longer shows any image, it means that you have not performed a correct installation. Check carefully for loose connecting cables
Advice
- Replacing a monitor's LCD panel can significantly change the color gamut used by the display. To correct this problem you will need to re-calibrate the monitor. If this step doesn't solve the problem, try replacing its lamp.
- Learn about the regulations in your area of residence regarding the recycling and disposal of electronic components.
Warnings
- If during the repair, you damage any of the cables, the monitor will stop working. In this case you can try to take it to a professional repair center, but if the damage is serious there may be nothing more you can do.
- Protection fuses normally blow due to a more serious underlying problem. Simply replacing the component, without having identified and fixed the problem, will most likely only waste a second fuse. If you have a blown fuse, consider replacing your entire motherboard or even buying a new monitor. Never limit yourself to installing a fuse with a higher amperage to prevent it from blowing a second time, otherwise some other component could be irreparably damaged or even start a fire.
