If you have an old monitor or LCD screen in your hands that suddenly stopped working or you bought a used screen and found that it does not work, do not worry because we will describe what are the most common problems and how to fix them in a non-working LCD screen and how to fix them so that it is fully functional as if it were a monitor purchased from day one.
First of all we have to give you a warning, in this tutorial we are going to describe a series of procedures that require advanced knowledge of electronics, that’s why we are going to warn you that you are not doing anything that we describe here below if you have no prior experience in this area. In the same way, we remind you that if your monitor is still under warranty, send it back to the technical service of the manufacturer, which is better and more practical.
How to repair an LCD screen?
It is not necessary for us to tell you that you must first make sure that all the wiring is working correctly, because it is possible that the power cable or the one responsible for sending the video signal, whether it is DisplayPort, HDMI or any other interface just doesn’t work.
We don’t need to tell you that once this is done, the first thing we need to make sure is that all the parts are in perfect condition and that all the connections are properly soldered and, therefore, that there is no There are no broken parts or loose cables. This is especially recommended if you are trying to resuscitate a used or very old monitor that is not working. Also, be sure to brush and clean the various components of dust and dirt. Let’s not forget that dust is the biggest enemy of electronic components.
First check the digital circuitry of the LCD screen
An LCD monitor will always have a microcontroller, its memory and its I/O interfaces on a small board. This digital circuit is responsible for interpreting the signal and managing it so that images are presented correctly and is the first thing you need to look at when looking for problems in an LCD monitor.
The way to check it is very simple, but for this you will need a thermal camera while the monitor is in operation. If through it you can see how the chips heat up, then the power supply circuit is working perfectly. In case these are not transmitting heat, then it can mean two things: the first is that said part is faulty and it is time to change it, and the second is that the LCD screen problems are found in its analog circuitry.
On the other hand, if you see that these work perfectly, but you see that they overheat too much, do not hesitate to use Thermal pads on the parts whose temperature is higher than the average as a preventive measure. And by the way, be sure to reinforce the contact pins with new solder, as overheating can damage these connections and prevent them from working.
Replace Capacitors to Repair LCD Screen
If you see that the screen does not appear or does so in very low light, then we have an internal problem and it is none other than the capacitors in the internal circuits of the monitor are broken. So what we have to do is open the screen and replace them with others with the same technical characteristics in the process. We don’t need to remind you that this is a very delicate operation which without knowledge could ruin the health of your monitor. To find out which capacitors are malfunctioning, just grab a multimeter and check if they can hold voltage. If you see they can’t, then this will be the one to change from the internal PCB of your LCD screen.
If you can do this correctly, you will have successfully fixed one of the most common of these problems on your LCD. So never throw away a monitor of this type because it does not turn on, a good change of capacitors well done will give it a second youth.
If none of the above works, you need to repair the transformer
Another general problem with an LCD screen to be repaired is simply that its internal power supply is not working properly. This is the step you need to take if you have changed all the capacitors and you are seeing how the issue that the screen won’t turn on or show a dark image continues to occur then you will need to ask yourself if the problem is the current source.
For cost reasons and for mass production, you will find that the different LCD monitors of the same brand use the same power supply, which is generally a small box mounted on the PCB, with its own circuitry or, failing that, to be found on another deck with a different color from the main one. To verify that the transformer does not have a problem, put the multimeter in short detect mode and measure the opposite end from which the AC current is taken from the AC outlet or from the battery if it is coming from a computer portable. If you see that the amount of voltage output is zero, the power supply will need to be replaced.
Keep in mind that this is one of the LCD monitor issues you will encounter if you are in front of a unit that is several years behind. So if you bought a used unit that initially didn’t work, you may not only need to update the capacitors, but also the power supply.
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