What to do if the phone backlight goes out? What to do if the tablet screen does not work The power supply on the tablet is mixed up and the backlight disappears
There are two main categories of reasons why the screen on a tablet does not work - due to mechanical damage or due to a software glitch. With the first category, everything is clear - if your device is dropped or someone damages it, the screen on it cracks, as a result of which it stops working correctly. The second category of reasons is more difficult to diagnose, but it is much easier to deal with this kind of problem.
Thus, users quite often complain that the screen has stopped working and does not respond to touch in any way after charging, installing new applications on the device, or visiting any websites. All these problems are caused precisely by software failures, which, unfortunately, happen on devices running the Android operating system quite often.
What to do if the tablet screen does not turn on
If there is no mechanical damage to the screen, but it does not turn on, you need to perform a number of simple steps that can help “revive” your device. Step one is to unplug the battery, wait 30 seconds and put it back in place. You can remove the battery from the tablet by simply opening the back cover of the device. This procedure is necessary because it allows the system itself to reboot and theoretically can eliminate a software failure.
Step two - reset your device to factory settings. You can do this even if the touchscreen of your tablet does not respond to touch. Here you should be warned that the instructions below are typical for most tablets, but not for all, so you should first find out how to hard reset your device. Before resetting the settings, you must turn off the tablet and, just in case, remove the memory card and SIM card from it.
Next, press the volume up key and the power button at the same time. After these manipulations, the device should vibrate and a menu will appear on the screen. In this menu, use the volume keys to select “Settings” and then “Format system/Restart Android”. After this, your device will begin to reboot, and all settings and programs that were installed on it will be deleted.
Step three - reflash your tablet. If the first two manipulations did not help, and the screen still does not work, but is not mechanically damaged, then flashing the firmware will help. Most users are scared by this word, but in fact there is nothing scary about it, since it only means reinstalling your operating system - just like on a PC. If you have never flashed your tablet, then it is better to ask someone more experienced to do it, so as not to completely “kill” the device.
Tablet screen replacement and repair
If the tablet screen does not work due to mechanical damage, which includes not only cracks, but also damage to the cables, then it should be replaced. It is worth noting that replacing the screen on a tablet should be done as quickly as possible, even if it works. This is due to the fact that if there are cracks, after some time not only the touchscreen, but also the matrix may fail, and replacing it will cost much more.
At the same time, it is highly desirable that the tablet screen be repaired by specialists, since if you try to do it yourself, you can only aggravate the situation. Thus, if there is mechanical damage on the display of your device, the best solution would be to contact service centers or companies that provide repair and maintenance services for mobile devices.
Read 12091 once
Every tablet owner may have a problem with the screen working or turning on. Of course, this problem can be easily solved by simply taking it to a workshop. There, experienced specialists will be able to bring your gadget back to life for a fee. But there is another option; you can conduct diagnostics yourself and determine why the screen on the tablet does not work.
Before starting diagnostics, you need to determine the nature of the problem. It can be of two types: this is mechanical damage to the screen, which could occur as a result of certain actions or a software failure. As a rule, mechanical damage can be seen with the naked eye. In such cases, it is better to give your tablet to a specialist, because without experience and certain skills it will be difficult for you to fix it.
Another type of problem is a software glitch. It can occur for many reasons. For example, the tablet stopped turning on after charging it or installing any applications or games. Failures can also occur as a result of visiting dangerous sites. In this case, the problem can be solved independently without any outside help or additional expenses.
Before you begin restoring your tablet, make sure that it has not suffered any mechanical damage. Then you should disconnect the battery of your device and wait a few minutes. Next, you need to insert the battery back and try to restart the tablet. This procedure allows the gadget's operating system to completely reboot. Very often this is enough for your assistant to begin functioning normally again.
If this procedure turns out to be useless and the tablet screen still does not work, you should try to reset all settings to factory settings. In almost all tablets, this function is implemented by simultaneously pressing the power key and adjusting the device sound. If you did everything correctly and the reason is a software failure, your tablet should vibrate, and a menu with settings will appear on its screen. In the menu, use the volume keys and the power button to select: Settings - System format - Reboot system. After this, your gadget will start again, but all previously installed games and applications will be deleted. This way you will roll back all settings to the original level.
If the tablet does not respond to key presses, you should read the instructions for it. Each device must have its own emergency method of rebooting the system. Before resetting all settings, it is recommended to remove the SIM cards and memory cards from it.
If the method you found in the instructions does not work, you need to take the tablet to be reflashed. In this simple way, you will completely reinstall the entire operating system of your gadget. It’s better not to try to reflash the tablet yourself, this can lead to more disastrous consequences.
My friends brought me two tablets and asked me to repair them myself if possible. Tablets TEXET and QYSTERS T72H3G.
The malfunctions of the tablets turned out to be the same for both, they did not charge and there was no display backlight.
Charging repair:
The problem with charging the tablets was in the USB (socket), on the TEXET it was soldered, it was simply loose, but on the QYSTERS tablet I had to change it. I couldn’t find a native USB socket for QYSTERS in stores, so I had to select it visually; the USB socket with the tag on the Z80 bag fit. It was a little bit shorter, but otherwise it completely matched, and even the contacts were a little longer, which made it more convenient to solder; after replacing the socket, it began to charge, the connector fit very tightly.
(I didn’t take a photo of the nest itself, I forgot)
note: For the rest of the tablet repairs, a donor (MID) PD20 was purchased for 300 rubles (since I could not decipher the dc-dc converter, and the store did not have IN5819 Schottky diodes in the SOT-123 package)
Backlight repair on tablets:
I began to deal with the backlight in the TEXET tablet and visually saw a dot on the diode near the dc-dc converter, the diode was broken and stood between the 1st and 5th legs of the converter (the converter itself has 6 legs, unfortunately I did not remember its markings). The markings on the diode cannot be distinguished because of this burnt-out dot. Having looked at the backlight diagrams from other tablets, I realized that there was a Schottky diode there, so I took a labeled diode from the “donor” SL transcript IN5819 and soldered it, it turned out that the cathode was to the 5th leg, the anode was to the 1st leg of the converter.
The dc-dc converter itself rang, there was no short circuit, so I decided to check and turn it on. I soldered the battery terminals into place and began to measure the voltage while the tablet was turned off; on the diode it was about 3.3 volts. I turned on the tablet, the screen lit up, the brightness was good (not dim), I measured the voltage on the converter:
1st leg: 1.2 volts
5th leg: 9 volts
the brightness was adjusted and nothing got hot, and the repair was completed.
I turned on the second QYSTERS tablet and the dc-dc converter was heating up for the backlight; in the off mode, the current consumption was 130 milliamps. First of all, the diode rang (marking S.J.) he also stood between the 1st and 5th legs of the dc-dc converter (6 legs are his marking 0B4V1 transcript AP3127B025MR) it was ringing like it was broken, I decided at the same time to check the converter itself, everything was ringing short (circuit) it was due for replacement, after I removed the dc-dc I checked the diode and it was broken.
important: (I made a mistake in the photo: the diode is not 1N5819 but IN5819)
I couldn’t decipher the markings of the converter and diode (decoding the converter AP3127B025MR suggested in the comments, thank you). Therefore, instead of the SJ diode, I soldered SL ( IN5819), and I started looking at the converter on the “donor” board, and found it with this marking based on a similar wiring CDC0B, carefully unsoldered it and installed it instead of the converter 0B4V1. In the harness I checked the capacitors for breakdown and two 3.3 Ohm resistors, they were intact. I measured it in the off state and there was no more current consumption, soldered the battery terminals and turned it on. The backlight appeared and the voltage was measured:
1st leg: 1.3 volts
5th leg: 8.8 volts
The brightness adjustment works, I checked the CDC0B converter, it does not heat up, the inductance is cold.
M874 MB V2.0 board
view of other elements:
DC-DC converter pinout:
An approximate diagram of how the backlight works on tablets:
Can be replaced:
Schottky diodes: SJ on SL (SL marking stands for IN5819 housing SOT-123)
DC-DC backlight converter chips: 0B4V1 on CDC0B(case SOT-23-6) (possibly suitable for replacing RT9293B; circuits are similar).
note: Sometimes it happens if you take a converter from a donor (which is different from yours) and your diode, inductance, DC-DC converter starts to heat up, the voltage is too high or low, then for stable operation you will also need inductance from the donor from the harness of this converter.
The tablet screen may not work for a number of reasons. Let's look at different situations to understand how to act in this case:
There is no picture on the screen, it is dark and does not work. Various circumstances can contribute to the appearance of such a defect. For example, if the device does not charge or the power circuit fails, and the user does not know about it, he may decide that the problem is in the screen. Try to find the "Reset" button and reset the settings to factory settings. Of course, the issue could be in the display itself, but in this case, most likely, we are talking about a hardware failure. If the backlight is on when you turn on the device, but nothing else happens, then the problem lies in the screen. Take the tablet to a service center for diagnostics. It may need to be replaced.
The image on the display is distorted or shows cracks or chips. Shocks and falls are the main enemies of mobile technology, so if the tablet’s screen does not work, think that maybe the device was dropped or moisture got into it. If such a problem really happened, then most likely the screen will have to be replaced with a new one. But you need to carry out diagnostics first, since only the protective glass may be damaged. The cost of replacement in this case will be much less.
There is an image, but it is impossible to unlock the tablet or the screen does not respond to commands. Carefully inspect the device: if scratches, cracks, darkening or other defects are visible, then the resistive layer may be damaged or delaminated. In this case, most likely, replacing the touch glass or replacing the touch glass controller will help. In addition, such manifestations often indicate software failures, virus penetration, etc. If there is a picture, but the tablet screen does not work, try resetting the settings. Reflashing the device can also help, but doing it yourself is not recommended.
If you are not an electronics specialist and do not have relevant experience, then it is better to entrust tablet repair to professionals. Even if the tablet screen does not work due to a software glitch or a simple replacement of the protective glass is required, only a specialist will return the equipment to working order in the shortest possible time.
There are many little things that we don’t even pay attention to that affect our comfort in life. And a change in usual conditions can sometimes become not only a big surprise, but also a problem. For example, the backlight of the phone. While the device operates in the usual way, it is unlikely that a person will think about how its disappearance could affect the operation of the device and personal comfort. However, at one moment it may disappear, bringing unusual discomfort.
So, what to do if the phone’s backlight goes out? If standard user manipulations with turning it on and off, removing the battery and restarting the device do not bring the desired result, you should not panic. Most phone owners needlessly get scared and think that it’s time to replace the display, without thinking about the feasibility of this procedure.
Display backlight key failure
The reason for the disappearance of the backlight does not necessarily have to be serious, due to moisture or flying onto the floor from a height. One of the most common causes of problems with the backlight is a breakdown of the display backlight key (the transistor in the display backlight power circuit that ensures its operation) and in order for everything to return to normal, it is necessary to replace this spare part.
After this, it will be necessary to completely replace the software of the mobile device. It is impossible to bypass this procedure, because after replacement there will be a need to configure the parameters of the power controller that supplies voltage to the transistor. Therefore, you should take care in advance about saving important data stored on your phone - otherwise, it will be lost forever. Considering this fact, before contacting the service center, be sure to make a backup copy of the necessary data.
Driver assembly failure
The second probable reason for the disappearance of the backlight is in the driver microassembly. Self-updating is strictly not recommended, because there is a high probability that an inexperienced user will simply kill the gadget, only aggravating the problem.
It should be remembered that any problem with the backlight (it turns on spontaneously, goes out too quickly) may indicate that it may soon go out. If you notice something strange in the behavior of your unit, do not delay and immediately contact the service center. In some cases, it will even help you save money.
The third reason why the backlight may disappear is very trivial and common. These are trivial problems with the latch of the display connector. Sometimes it’s enough just to tighten the latch of the display connector well and the mobile device will work as it should again. Sometimes it is necessary to replace a loose connector or thicken the display cable to ensure normal contact.
And, of course, we cannot help but say once again that the backlight, of course, can disappear due to a fall or the formation of condensation due to moisture. In fact, problems associated with the disappearance of the backlight after such incidents (if the display is not broken, of course) can be classified as follows:
- There is no backlight, but there is an image - most likely, the problem is in the backlight driver or in the coils.
- There is no backlight or image - there may be a problem with the processor.
Remember that only a qualified technician can accurately diagnose problems. Independent attempts to “diagnose” a mobile device or try to estimate the extent of repairs will most likely not lead you to a constructive result.
