There is no sound on the TV screen. The main reasons why the TV does not show an image but there is sound

Samsung LED TVs are reliable and popular devices. In the latest generation TVs from the manufacturer, faults occur in 5-7% of users in the first year of operation. The most common problem is the absence of an image on the screen.

There is no image or sound on the screen

The Samsung TV appears to be turned off and does not respond to remote control signals.

• No power supply - check that the TV is connected to the rear panel and the outlet.
• Video processor malfunction - diagnostics and qualified repairs are required.

There is no image on the screen, there is sound

The TV screen appears dark, but the device responds to remote control signals. When you turn it on/off, a splash screen with a company logo appears.

• No signal - check the external antenna connection.
• Incorrect brightness settings - go to the "Pictures" menu and adjust the brightness, turn off the power saving mode.
• Faulty LED backlight - requires disassembling the panel and replacing burnt out LED strips.
• Failure of the inverter - the electricity converter that supplies current to the LED.

If the inverter and LEDs are faulty, there is actually an image on the screen, but if there is no backlight, it becomes very dark. To diagnose the problem, darken the room and hold a flashlight to the screen. If you see a picture, then the problem is with the LEDs or the inverter. You can replace faulty parts yourself or call a specialist.

The image is very distorted

The image on a Samsung LED TV looks like a narrow stripe; a solid or color screen appears. The problem appears immediately after switching on or after 5-10 minutes of operation. Sometimes the picture on the screen freezes, the screen becomes dark, and after turning it off and on again the problem appears again.

• Failure of the video amplifier or processor (in 95% of cases only one color appears on the screen). It is necessary to call a teleworker to carry out accurate diagnostics and repairs. It is impossible to fix the problem yourself without special equipment.
• Problems with the LCD matrix - the cost of repairs can reach up to 80% of the cost of the TV. Repair is only advisable for new TVs under warranty.

You can determine the failure of the LCD matrix yourself. To do this, with the device turned on, lightly press on the screen. If the matrix is ​​faulty, the image will freeze at the point of pressing, and blackouts or severe color distortion may occur. Matrix failure is rarely sudden; as a rule, with this problem, “dead pixels” first appear, then their number increases.

The screen suddenly goes blank and the TV turns off

Samsung TV works fine, but suddenly the screen goes dark and the device turns off. When turned on, the problem may recur many times.

• The energy saving feature is enabled - go to settings and disable it.
• The Sleep timer is activated - check if the timer is enabled and disable it.
• The TV goes into standby mode - signal problems for more than 10 minutes, check the connection.

No picture on Samsung LED TV

We offer step-by-step instructions for restoring the screen performance of a Samsung LED TV. In 50% of cases, the lack of an image can be eliminated yourself without calling a specialist. So, what to do if the image on your Samsung TV disappears:

• Check that there is power and that all plugs are connected correctly. If there is electricity, you do not feel the characteristic burning smell from the TV or outlet, the failure lies in the TV itself.
• Check the functionality of the device: presence of sound, loading of the screensaver when turned on, operation of the remote control and buttons on the case. If the TV does not turn on, try unplugging the plug from the socket for 10 seconds and then plugging it in again. If there is still no image, then go to step 3.
• Restore your TV to factory settings. Go to the menu "Support" - "Self-diagnosis" - "Reset". After entering the PIN code, the TV will return to factory settings, having first turned off and on.
• On TVs that are equipped with the Auto Diagnostic function, you can run a picture test. During testing, the device checks all settings and operation of key elements. If the test does not start, then the problem cannot be solved without disassembling the TV.

Life hack: If your Samsung LCD TV responds to the remote control and there is sound but no picture, then try raising the volume to maximum. In some cases, this simple method helps restore a normal picture.

If none of the above helped return the image to the screen, the TV must be disassembled to identify the cause of the breakdown and fix it. It is better to entrust the disassembly of the device to the service center employees or an experienced teleworker.

Self-disassembly of Samsung LED TV

The principle and procedure for disassembling Samsung TVs is virtually the same for all models. You need to place the device face down and unscrew the rear panel bolts and open the latches. Carefully remove the panel and inspect the microcircuits. As a rule, there are two of them. Check the connection of the loops. If everything is in order, then you should check the LED backlight and inverter.

The normal input voltage to the inverter is 10-15 Volts, the output voltage is 60-120 Volts. The parameter depends on the screen diagonal: the larger it is, the greater the voltage. If there is no voltage or much lower than normal, then the inverter is faulty. It needs to be replaced or repaired. Is the voltage normal? We check the LED backlight strips by applying voltage to each. Having identified a faulty tape, we replace it with a new one. If all strips are normal, the LED driver is probably burned out and needs to be replaced.

Regardless of the brand and model of the device, owners are faced with the same problem - there is no image on the TV. In this case, the sound may work normally, or it may disappear. Initially, you can independently diagnose the device, as well as eliminate detected faults. However, the cause of the breakdown is often much more serious, then it is better to entrust all work to restore the functional characteristics of your TV to professionals.

The image on the TV disappeared: diagnostics and ways to solve the problem

First of all, you need to determine the nature of the problem. Along with the complete disappearance of the picture, this could be:

• Periodic flickering of the screen, small ripples.
• Temporary interruption of the video signal.
• Light or colored streaks appear on the screen.
• Flashing backlight elements.
• Poor image quality (the picture is blurry, objects in the video have a red or green outline, the image consists of small squares).

Some modern models of plasma TVs (Samsung, Sony, Philips) have a function that allows you to turn off the image while maintaining the sound. You may have accidentally used this feature of your device. If not, proceed to diagnostics. There may be several reasons for the deterioration or complete disappearance of the picture:

1. Network problems.
2. Damage to the power cable or its partial disconnection (especially important for CRT TVs).
3. Failure of the electronic amplifier (inverter), which supplies voltage to the backlight elements of the LCD screen.
4. Faulty power supply elements.
5. Damage to the matrix, system board or backlight unit.
6. Deformation of loops, convectors, decoders.
7. Swelling of the capacitor housing.

Your steps to resolve the above problems may be as follows:

• Restore the connections of cables and wires; if their integrity is damaged, replace them with new ones.
• Go to the device settings and check that they are correct.
• If the device is connected to a Wi-Fi network, make sure the signal is strong. If necessary, reboot the modem or optimize its settings.

A simple trick often helps: increase the volume to maximum, then reduce it to the desired level.

If all display elements are normal (the screen works, the splash screen appears when turned on and the channels are switched), one of the above actions will most likely help resolve the problem of the lack of image. Otherwise, you will need the help of a qualified technician.

Both sound and picture are gone

It happens that when you try to switch channels, the image first deteriorates, and then the picture and sound disappear completely. In this case, check the connection of the plug to the socket - the contacts may be loose, causing the power to turn off.

If the socket and cord are in order, and after turning on the TV you see only a black screen without sound, then it is quite possible that the motherboard is burned out or the power supply is faulty.

Don't forget to also check the condition of the cables and the integrity of the speakers.

If you used HDMI as the main interface when connecting your computer or laptop to the TV, and the image still did not appear, pay attention to the following indicators:

• Check cable integrity. If possible, test it with another device. There is no point in repairing a deformed cord - it is easier to buy a new one.
• Check the condition of the ports for external visible damage.
• Go to TV settings. Make sure that the exact HDMI port you selected as the video source was occupied by the cable. As a rule, devices from modern manufacturers (LG, JVC, Samsung, Sony, Philips, Toshiba) have 3-4 such ports. If necessary, make the necessary settings.
• Go to your computer settings. Check whether the video card is configured to transmit images to the TV screen.
• Don’t write off the human factor either - perhaps you simply connected your computer to the TV incorrectly.

If all the settings are normal, and the cables and ports are working, but there is no image via HDMI on the TV, contact an experienced specialist who will perform a full diagnosis, identify the causes of the breakdown, and also repair your device.

Do-it-yourself TV repair or professional services?

An LCD or plasma TV is an expensive and complex piece of equipment that requires careful handling. Naturally, if any problems arise in its operation, you need to carefully examine the outer casing for visible damage, and if repairs are necessary, call an experienced technician.

If you change the TV settings, check the connection to the network or computer, replace cords and cables, you can do it yourself, but it is better to entrust the replacement of components and parts to an experienced technician. The specialists of our Remontano service center will professionally perform prompt repairs of any brands and models of televisions:

• We have craftsmen on our staff who have the knowledge and skills to quickly repair even the most complex equipment.
• We work only with trusted suppliers of spare parts, so you can be confident in the quality of the parts installed.
• All types of work are covered by a guarantee.

To submit a request to call a specialist, call

Modern TVs are reliable and functional devices. However, even they are prone to breakdowns. Users especially often complain that the image on the TV has disappeared, but there is sound. In this article we will look at the key reasons, how to fix them, and what to do in a particular case.

Main reasons

The problem is common, in some cases you can even deal with it yourself. The most common reasons when there is sound, but no picture on the TV:

• cable problems;
• power supply failure;
• problems with the color block;
• the matrix has failed;
• the inventory burned out.

To restore the image, you need to diagnose the breakdown and carry out repairs. Of course, you can contact the service center. The technicians will fix the problem, but the price of their services will be very high.

Checking the cable

If the TV with Smart TV does not show an image, but there is sound, you need to carefully check the wires transmitting the image:

1. HDMI.
2. Antenna.
3. Wire from the provider.
4. Plugs.

We carefully check all connectors and the integrity of the wires. We take out the plug and check the contacts. If sound appears, but the image is bad and constantly disappears, then you need to check the antenna.

Matrix problems

A common problem why the image on the TV disappears, but the sound works is when the matrix is ​​broken. Signs:

• the picture jumps;
• the video is displayed on half the screen;
• stripes of different shades appear.

The matrix fails mainly due to careless actions of TV owners - an accidental fall or a strong blow. A complete replacement of the part will be required; in some cases it is better to immediately purchase a new TV. The cost of replacing the matrix on some Samsung models will be comparable to the price of new devices.

If problems arose without any prerequisites, for example, the picture began to double or the image quality sharply deteriorated, then repairs are possible without replacing the entire module.

It is impossible to repair the matrix yourself without the proper skills. Already at the preparation stage, serious problems will arise, since it is very difficult to find the necessary spare parts. They will need to be ordered from specialized stores, but choosing the right one will not be easy.

Capacitor burned out

Capacitors are unstable to strong voltage surges, so they fail with enviable regularity. The defect appears like this:

1. Suddenly the screen goes black.
2. After a few minutes of operation, the broadcast disappears.
3. There are problems with brightness.

If you remove the back cover of the TV and look at the board, you will see swollen capacitors. In special cases it may even explode.

Usually, a fuse burns in parallel with the capacitor. When diagnosing, it needs to be checked. It is best to entrust the replacement of the capacitor to a specialist.

Testing the matrix cable

When your LG TV has sound but no picture, inspect the matrix cable. Most often, the following points indicate its breakdown:

• periodic disappearance of the broadcast;
• the image ripples, interference appears;
• Various screen distortions appear.

No one will repair the cable; it is much easier to completely replace it. It is impossible to repair the element yourself. The cable is a fragile part and can be easily damaged.

Backlight

If the backlight lamps are broken, it is very easy to check. We turn on the TV in the darkest room possible, and shine a flashlight closely into the monitor. An image should appear in the place where you shine the light.

Backlight lamps for TVs in a very wide price range. They can cost very little or very much. It is unlikely that you will be able to replace this part yourself, so once you have determined the reason, feel free to contact the service center.

What to do with the inverter

If your Samsung, LG, Sony or any other model does not have a picture, but there is sound, the inverter may have failed. This breakdown has too many signs:

• the broadcast is distorted;
• sound appears immediately, but the image appears only after a few minutes;
• the picture is too dark, it is difficult to see what is happening on the screen;
• There is a constant ripple on the screen.

After a detailed inspection and diagnosis of a failed inverter, any person who knows how to use a soldering iron, a multimeter and has knowledge of electronics can repair it.

power unit

If, when connected to power, sound appears on the TV, but the broadcast does not or appears with a significant delay, the breakdown must be looked for in the power supply. First of all, you need to carefully inspect it and only then make a decision about repairs.

1. We remove the back cover, check all the wires for creases, and inspect the fuse.
2. We find all the capacitors and check if they are swollen. If any are found, they need to be changed immediately.
3. Test voltage. The obtained parameters must match those presented in the documentation for the TV.
4. The TV reacts to minor taps, the image jumps, colors change - you need to check all contacts.

If there are no visible defects, then you cannot do without the help of a specialist.

In a situation where there is no image, but there is sound, you can take the following actions:

1. Turn off and turn on the TV after a few minutes. There may be a system failure.
2. We check the antenna cable connection and connectors. The wire may have broken.
3. Raise the volume to the limit. Usually after such actions the TV begins to work stably.
4. If there are constant power surges in the network, install an uninterruptible power supply.

Use the TV carefully to prevent mechanical damage and accidental exposure to moisture.

In conclusion

This article presented all the moments when the broadcast may be missing on the TV, but the sound may work without interruption. To repair a TV, you need to understand electronics. If the knowledge is not enough, it is better to immediately contact a service center so as not to completely break your TV.

Seal

LG TV malfunctions

LG KF-21P10. When turned on white screen all over the screen, beam reversal, TDA6108 and zener diode on leg 5 (IK) 7V5 are faulty.

LG CF-20F30. Automatically switches off to standby mode from 10 minutes to an hour. The entire board was literally “plowed with elephants and camels”; only the management percentage was left untouched due to its high cost. Reason for turning off the LG CF-21F3 processor. Immediately after switching on it goes into standby mode. No Vsync on processor. Fault-break R15 4.7k

LG CF-21D33E. Breakdown of the deflection system Pianzhuan QPC 29-90-54. After removing the “coals” and compound from the opposite side, routing the turns, and pouring hot glue, the OS started working. The mixing turned out great.

LG CF-20E60K. there is no frame scanning in the devices: Open circuit in resistor R311 2.2 ohm.

LG CF-20K50E. It is in the duty room and does not turn on either from the remote control or from the TV panel. It turned out that one 4.7k resistance in the ceramic assembly near the control processor was broken. I hung a similar resistor on the other side of the board: the box worked, but the raster was compressed vertically and shifted to the left. I didn’t go into the service, I changed the memory, the raster became normal.

LG CF21D70. When turned on, it goes into standby mode. The reason is the breakdown of the 2N4148 (150V) diode according to the D408 circuit. Already 3 cases in 3 months.

LG CF-21K49. Does not turn on or has a narrow vertical stripe on the screen. The capacitor C411 334/200V must be replaced.

LG-CF21D79. Oversaturated color image b/w no, as if there is no brightness signal. Replacing the TB1238BN video processor did nothing. The SECAM TA1275AZ chip turned out to be faulty.

LG CF-21D70. When turned on, it goes into standby mode, and then goes out completely. The analysis showed that when mains voltage is applied, the output voltage +V smoothly increases to more than +160 V (norm +125V), and then the internal protection is triggered and the generation of the power supply is disrupted. Analyzing, I discovered a defective electrolyte C824 4.7 μF 50V (leakage, drying out or increase in internal resistance at HF), installed between 4 pins. optocouplers IC801 and 7 pins. STRS5707. What pleases is the timely internal protection, which did not allow the murderous +V=160-180V to run rampant.

LG-21D70X. when turned on, switching programs does not settings information is saved. After pressing the power button, the TV switches on to LINESVC mode, from which it goes into normal mode after pressing the TV/AV remote control button. After replacing the 24C02 memory and turning on the TV again switched to LINESVC mode, then after pressing the TV/AV button on the remote control, the TV switched to normal mode with the functions of saving settings restored. No additional actions were required to “firmware” the memory chip.

LG CF-20D60. Doesn't turn on, when measurements are made in the power supply, a startup occurs. It is necessary to replace the 4.7mFx50V capacitance (located in the radiator section 5707).

LG CF-21D70. Spontaneous transition to standby mode. It varies on different channels, on some after 5 minutes, on others after 10 minutes. Try replacing the electrolyte in position C408 with a nominal value of 160V1mF, it shrank to 0 and in addition there was a leak.

LG CT-29K37E. It enters operating mode after 5-6 attempts to turn it on and off. It is necessary to replace C808 (100.0x35V) in the power supply, which is assembled on the STR-F6656 chip.

LG CF-21F89. MC994A chassis. Symptom - turns on for a few seconds then goes to st-by. During switching on, the line transistor manages to heat up. The line coil in the OS is shorted.

LG CF20F30. Fuse is on. The diode bridge and the IC802 STR5707 chip are broken. I soldered the bridge from KD105s, bit off pins 1 and 3 of the microcircuit, turned it on, there are trigger pulses on the 4th leg. I hung the KT872A transistor (k-1n, b-3n, e-2n) on the wires, turned it on and it works. Tr-r placed on a suitable radiator.

LG CF-21D70. MC64A chassis . Spontaneously goes to “duty room”. Regardless of operating time, heating or cooling. Replacing processors and memory did not give any results. As a result of a long search, the defect was finally identified - the C408 1uFX160V in the Q401 circuit had dried out. In these same TVs, B.P. does not start. — drying out of C824 4.7 μfX50v in the optocoupler circuit.

LG CF-20K51KE. Line transistor breakdown Q402 D5702 on the body, with burnout. After replacement, the new one flew out within a second. I replaced Q402 with BU2520DX, they are more reliable. A thorough check of the harness did not bring any results. I disconnected one output of the OS horizontal coils and briefly turned on the TV. The screen lit up with a stripe. I turned it on briefly with the OS. The screen lit up with the screen shrinking. The transistor remained intact. Replaced OS. The result is positive. I found no defects in the broken OS.

LG CF-14G20R. Weak sensitivity. There is interference and noise in the image. The IF filter of the K6265K radio channel was to blame for this disgrace.

LG CF-20F60. Received from another workshop with a diagnosis - the processor is faulty. The device behaved in a rather original way: at first it started working, after five minutes it froze and did not want to work anymore during the day. After resting for about twelve hours, he started working again, froze, and everything was repeated all over again. Three resistors in the AR02 assembly turned out to be faulty, two of them were connected to the pins of the processor’s I2C bus, and the resistor values ​​did not change upward, as is most often the case, but downward. Instead of the required 4.7 kOhm it became 2:3 kOhm. For reliability, we had to replace the entire assembly with ordinary resistors.

LG CF-21K50E. There is sound, no picture, the screen is dark. Upon opening it, it turned out that there was heat, and there was also voltage on the cathodes. As the accelerating voltage increased, a bright narrow horizontal stripe appeared. The frame microcircuit LA7830 and the 1 ohm resistor for powering this microcircuit turned out to be faulty. The microcircuit flew out due to increased voltage from the power supply (145 volts). The reason is that the electrolytes in the circuit of the power supply microcircuit (STR-S5707) have dried out. After replacing the electrolytes, the power supply began to produce 115 volts.

LG CF-14E20B. MC-41B chassis. Lights up red (DR indicator), does not respond to buttons, +B = 43V. The reason is X01 (for some reason it was 3.6MHz). According to the 4 MHz scheme, because it didn’t turn out - I put it at 4.43.

LG CF-20F89. Doesn't turn on. Power supply for STRF-6707A(not to be confused with STRS-6707). After replacing the chip, the power supply started up, but after switching from standby to operating mode it took five seconds. went to standby again. Not right away, but I thought of connecting the deflector. It turned out that without her the TV would not leave the control room.

LG CF-21S10E. No personnel distribution, change the TDA8351 frame chip. The image is compressed from the bottom to half the screen, we change the TDA 8842 video processor, the image is normal, but don’t be happy, everything can happen again, and the TDKS 6174Z-8005A is to blame for this disgrace. At times it breaks through.

LG CF-21D70. When switching to operating mode, TDKS strikes. TDKS type 6174Z-8004B is faulty. Installed 154-375F without any structural or fundamental alterations. TV started working. The geometry is fine. I set up SCREEN and FOCUS and that's it. But there is a drawback - the screen is quite blue with blue lines arr. progress. As a result of the line transformer shooting, Q514, Q513 and Q512 (2SA1266Y) in the video amplifier failed. Instead of 6174Z-8004B, another LG CF-21D70 TV had 154-375E.

LG CF-21D70. When you click on the "Network" button cash indicator mode lights up for 2-3 seconds and goes out. The voltages from the power supply when you press the “Network” button have nominal values ​​for 1 second. then they smoothly decrease to 0V within 1-2 seconds. The “Network” button, which supplies power to the TV only while you press it with your hand, is faulty.

LG CF-21F30K. The power supply does not start: replacing the line transistor TT2140 with 2SD2499 and TDKS 6174Z-6040C.

LG-CF 20F39. Vertical line. Open capacitance 0.364 µF at 400V in the line.

LG-CF14E60 on MC-64A chassis. The power supply turns off. At first glance, all the parts are intact; replacing the ic802 microcircuit and transistor, the Q810 C3198Y power stabilizer with a zener diode in the base did not give anything. A thorough analysis revealed a capacitor with a low capacity C824 4.7×50V. After replacing the capacitor, the unit starts up. By the way, in earlier releases of these models there was a 220.0x5V capacitor, there were no problems.

LG CT-20T30KE. After a while it starts lose 1 channel or all at once. The vertical size may vary. He may pass out on duty. It may become uncontrollable. The sound disappears. Line scanning disappears for a short time, etc. Replacing the memory (you can install a clean one) and quartz did not give any results. Replacing the TDA9381PS\N2\3/0701 processor. When installing processors with different firmware, the TV does not leave standby mode, but changes the firmware in the memory chip as it pleases.

LG CT-20T30KE. No PAL color. Replacing quartz 12,000 MHz. Quartz, even new ones, may not meet the tolerance.

LG CF-20F39. No image. There is a vertical line on the screen. The capacitor in the circuit of the horizontal coils is faulty (I think C412) with a nominal value of 0.36 μF x 400 V - open.

LG-СF21F60K, White slanted stripes on a dark screen, when the antenna is turned off, light snow appears. According to the owner, the image disappeared when the video camera was connected via the low-frequency input LF. Connecting the 42nd processor leg (external video input) through a 1 Kohm resistance to ground restored the operation of the TV via HF. and according to N.Ch.

LG CT-15Q91KE. No raster. When adding accelerating voltage, a gray raster with OX lines appeared. There is no video signal or OSD. When switching channels, there is a slight attenuation of the raster. The OX lines are stationary - they do not react to the presence or absence of a signal at the antenna input. Assembled on the TDA9381PS/N2/3I0792 IC. All supply voltages are normal. FB, SSC, etc. input. impulses are normal. The wiring has been checked inside and out, including on the kinescope board. The signal from the RGB outputs reaches the cathodes normally. At the RGB outputs of the IC (pin 51, 52, 53) there is absolute zero. At pin 50 IC (BLKIN - black current input) +7V. I couldn’t find a diagram, the normal voltage is unknown. I tried to ground it. Result: an image appeared, but with OX lines. There are flags on red, but the brightness is normal. The voltage at the cathodes is the same - about 150V. I alternately connect the RGB outputs to ground. After shorting R, an image without red appears. By selecting the resistor resistance between the output IK (IC TDA6107Q) and ground, I achieved the appearance of an image without OX lines. Denomination - 10 com. The image is bright, except for the flags in red. Conclusion: Loss of emission from the red cathode of the kinescope due to a high-voltage discharge inside the tube. As a result, the cathodes of the microtext processor IC are blocked. LG CF-21F30 Malfunction: no startup. The power supply is assembled using STRS5707. Dried C824 4.7x50v

LG-21D33. After 1-1.5 hours of operation the TV periodically switches off to standby mode within a few minutes. Then it goes into standby mode and does not react to anything. To turn it on again, you need to disconnect it from the network for ~ 0.5 hours. The reset circuit IC03 KA7542 turned out to be faulty.

LG CT-25Q20RQ. Does not turn on, standby indicator does not light up. In the break, R830 (like a resistor-fuse, a 0.47 ohm resistor is installed instead of it), is located in the secondary, and +12 volts are supplied through it.

LG CF-21J50K, CT-21Q41KE chassis MC 019A. The power supply does not start (clicks). Replacement of line transistor TT2140 with 2SD2499 and TDKS 6174Z-6040C analogue of HR8656.

LG CT-29K30VE. chassis MC 022A. No image or raster(the screen is black), there is sound, when the accelerating voltage increases, the screen turns greenish with reverse lines, when switching channels the image appears for a second, but without a blue tint and disappears again. Replacing the TDA6107JF video amplifier did not change anything, only after a detailed check of the wiring, the D903 diode on the kinescope board turned out to be leaking in blue, after replacing it with ours from MC-2 (there was no native one) the image appeared.

LG RT-21FA32X. The TV does not turn on from standby mode. The C820 200.0x160 turned out to be faulty.

LG CF-21D30. At different periods of time it goes into standby mode. Replace C408 and it is advisable to change C311 and C824.

LG CF-21D31KE. Chassis MC-019. The sound is accompanied by unpleasant sounds, it seems that either the loudspeakers or the ULF are defective. But a check showed that they were normal. The cause of the malfunction turned out to be the TDA9859 audio processor chip.

LG RT-21FB30M. No image, black screen, OSD available. The IF signal does not pass through, there is no video signal at pin 40 IC01 (CVBSINT) - transistor Q551 (2SA1980) is broken

LG CF-20J50K (Chassis MC-019B). Image shifted to the right by 10cm, color and synchronization are available. Open circuit C505(222J) of the filter of the 2nd circuit of the AChIF.

LG CF21F60K . Dark screen, when adding an accelerator, there is a weak picture with a reverse beam, there is sound, there is graphics. R456 is faulty, the ABL circuit is broken, after replacement the TV works.

LG CF21F60K. TDA9381PS\N2\3 changes to TDA9361PS\N2\4I0793 (from LG CT-21Q42KEX).

LG CF-21D30 chassis MC-64B. (The power supply is assembled on the STR-S5707) Malfunction: when turned on, the red LED on the front panel begins to blink constantly with a frequency of approximately 2 Hz, and relay clicks are heard in time with the blinking. The TV does not respond to either the remote control or the control buttons on the front panel. I left it turned on in this state. After about 10 minutes a wisp of smoke appeared. The problem was found on its own. A small capacitor C813 470pFx1000 V was smoking in the secondary circuit of the power supply (it shunts the +V rectifier diode). After replacing a capacitor with similar parameters, the operation of the device was restored.

LG-CF20F39 (Chassis-MC994A) No power supply starts, line transistor 2SD2449 is broken. In the harness I noticed “familiar” capacitors from the WOOYANG company. One of them is 0.334x400 in a cliff. Although TVs with such a malfunction have a vertical thread, the transistor does not knock out, so I also replaced the 1600 volt capacitor (also from WOO YANG).

LG CF 20S10E. The TV does not turn on in operating mode. Composition: ICO LG 20S10E IC 501, TDA 8842 S1. The problem is in the resistor assembly AR02 4.7k 9n in an open circuit: 0 ohm. Replacing the AR02 4.7k assembly restored the TV's operation. Also 1204 1184. To the above, we can add: failure of the TV to switch on to operating mode occurs when AR02 fails and when AR01 fails. But if AR01 fails, the memory is always intact! And when AR02 exits, a memory failure is possible, even a horizontal scan transistor may fail.

LG-21Q42KEX chassis MC-019. No horizontal and frame synchronization, there is sound. Replaced processor TDA9361PS/N2/4I0793 (OICTMH006C).

LG CF-21D30. The TV does not respond to channel switching buttons, confuses commands with the remote control, and periodically goes into standby mode. The m/s PROM 24С04 is faulty. You can replace it with a new one that is not stitched.

LG PT-53A82T. There is no information, specifically - the red beam on the cross in the menu option is not reduced. The STK392-120 is faulty, there are two of them - for the blue and red projector. After the replacement everything is fine.

LG CF-20F39 chassis MC994A. I came in for repairs with a worn out TDKS, and the resistor in the ABL circuit also burned out. Someone has already changed TDKS. After replacing the TDKS and R 33k, the TV started up. When measuring the supply voltage. lines, it was detected that it gradually increased to 150-160V; the protection did not work. Troubleshooting the stabilization circuit in the power supply revealed a dead optocoupler IC801. Replaced with PC120, everything went as it should.

LG CF-20D70. No line scan start. D408 1N4148 turned out to be faulty, although when checking there is no leakage, even with a digital device.

LG CF-20F30. Doesn't start. Turn off the horizontal scan and connect the control light. The power supply started up, the control light came on and all voltage appeared. However, the fault could not be identified in the scan. I had to go back to the power supply. It turned out that the capacitance of C824 4.7x50V was lost to 2.8 µF

LG CF-20F80 MS-84A chassis No picture, sound is normal, although service information is displayed normally. At high magnification on the SCREEN line, a very weak inverse image appeared on the screen along with reverse lines. The cause of this malfunction turned out to be the ZD741 8.2V zener diode on the ABL line. After replacing it, the picture appeared and the TV worked fine.

LG RT-21FA72X. The device after a thunderstorm. Malfunction: when turned on, an image appears for a second and immediately turns off into standby mode. The processor TDA9381PS/N2/4/0703 (OICTMPH006B) is to blame. Replaced by TDA9381PS/N2/4I0793 (OICTMPH006C).

LG CF-20K50E. Does not turn on from standby mode. On leg 4 of IC803 (STRF6654) 13 volts instead of 18.9 volts. C801 is faulty (100.0x35V).

LG RT-21FB30M. When turned on, a raster appears, but there is no image or sound. The menu turns on, all control buttons work. The setting turns on, but doesn't find anything. The culprit turned out to be processor IC01 TDA9381PS/N2/3I0792 (OICTMPH010A).

LG RE-29FA33X. The image disappears periodically and after 5 seconds. goes into defense. A staffing loss has been detected. The reason is the cold solders of the TDKS legs.

LG CF-21J50K. The TV is on, there is no reception on any channel, no sound. The TV works at low frequency. I replaced the selector and the TV started working.

The very first televisions are so different from modern technology that it seems there is almost nothing in common between them. In fact, the general principles of operation have been preserved, and some malfunctions of televisions of different models can be repaired in the same way. However, new causes of failure have also appeared related to the characteristics of the screen matrix, the design of microcircuits, and much more.

Trouble turning on or off

If the TV does not want to turn on, and the network connection indicator light does not even light up, then the problem is most likely with the power supply. It can burn out as a result of a strong voltage drop.

A similar reason may occur if the TV turns off spontaneously. If overvoltage protection is installed, it can turn off the device at the right time. If you know that the voltage was stable, then you need to check the power supply and look at the motherboard to see if any microcracks have appeared in it.

No response to the control panel

This is a fairly common problem, but in most cases it is associated with a malfunction of the remote control itself. You may have dropped it or spilled something on it and it stopped working. You should also check the batteries to make sure they are ok.

It happens that the remote control has nothing to do with it, and the problem is a malfunction of the remote control receiver on the TV or a problem with the processor.

Memory problems

It happens that you want to set up channels and remember them, but nothing works. This may be due to problems with the memory device. A similar situation occurs when you adjust the sound, turn off the TV, and after turning it on, the settings are not saved. It will be necessary to check the memory chip and, if necessary, replace it.

Buttons on TV don't work

If you press a button on the TV itself, but no reaction occurs, then you need to check whether the contact connecting the button to the microcontroller is broken. If all contacts are intact, then you need to look for the reasons in the controller processor.

Sound problems

The sound problem is caused in most cases by some problem with the speakers. We need to check that they are turned on, connected, and that all contacts are intact. There are problems with the bass amplifier, as well as with the sound processor. As a last resort, you need to look for a solution in the operation of the radio channel.

Poor or no image at all

It’s an annoying situation when the TV turns on and you can even hear sound, but there is no normal picture. The reasons for this can be very different, but they can almost always be solved. Whether you can solve them yourself or will have to call a specialist is another matter.

• When the image is completely absent, but the sound is excellent, this may be due to a malfunction of the matrix or video amplifier.
• The absence of a picture and periodic loss of sound may indicate that there are scanning problems.
• If there is sound and the screen lights up but does not show anything, then there is some problem with the video processor. The cause may also be interference in the tuner.
• It’s an annoying situation when the image only expands to half (bottom or top) of the screen. This indicates a malfunction in the matrix's vertical scanning. The vertical scanning module fails due to voltage surges and poor performance of the power supply.
• If a narrow vertical stripe appears on the screen, then something is wrong with the horizontal scan transformer; if the stripe appears horizontally, then there is a problem with the vertical scan.
• The image has become monochromatic or one color has disappeared. This indicates that the video processor or video amplifier is broken.

Individual matrix malfunctions

In a modern TV, a malfunction of the matrix becomes a big problem that can only be solved by replacement. The matrix, in essence, is the screen, or rather, its main part on which the image is built. The reasons for matrix failure may be the following:

• being hit by a hard object or falling;
• moisture entering the matrix contacts;
• manufacturing defect, electrical defect;
• wear and tear resulting from long-term operation.

Due to damage to the matrix, multi-colored stripes, black circles may appear on the screen, the image may freeze or be completely lost. Only a specialist can diagnose and replace the matrix, since there are many features of connecting and configuring the device.

Scanning problems

There are several indicators that indicate that there are problems with the frame scanning of the TV:

• the image has become smaller or shifted vertically;
• alignment is disturbed;
• lines appear in the image indicating the reverse path of the rays;
• there is no frame scan at all, etc.

In the complete absence of frame scanning, one luminous horizontal stripe is visible on the screen. Typically, all these cases of malfunction are associated with incorrect operation of the vertical scan generator unit. In the generator, the frame rate is set by capacitors, resistors, diodes, and transistors. If the TV has a kinescope, then the signal from the frame scanning unit is supplied to the deflection system. There may be problems with the contacts, or a breakdown in the deflection system may occur.

Only a person who is well versed in the design of the TV can fix problems with all these elements, so contact a service center.

From all that has been said, it is clear that most problems can only be fixed at a service center. With our own strength we can:

• check if there is voltage in the network if the TV does not turn on;
• check the antenna connector contact, whether it is connected well, try tuning other channels if the image is not of good quality;
• if there is no sound, see if the headphones are plugged into the socket, unplug them, plug them in and out again, make sure the sound setting is correct;
• replace the batteries in the control panel and check its serviceability.

Based on the signs that we described in the previous sections, you can determine how serious the problem is with the TV. After this, you can call a technician or take the device to a service center.

Today we will talk about why an LCD TV has sound, but no image, or vice versa - the causes of the problem and self-repair. We will also consider troubleshooting modern plasma or LCD when there is no sound or image on the TV

A very common malfunction of LCD TVs and monitors is that there is sound, but no picture. Most often the screen does not light up at all. Those. There is sound, but there is no image at all.

There are also a number of situations when something happens on the screen:

• The picture narrows to a strip (either immediately after switching on, or after some time)
• Screen white, red, green or other color
• There is an image, but it is almost indistinguishable (as if the brightness has disappeared)
• There is severe ripple or other noise on the TV screen
• The image blinks (flickers)

Why is there sound but no picture?

Most often, this happens because the screen stops lighting up (either the backlight lamps or the inverter supplying voltage to them are faulty). However, a black screen can also occur if other parts of the TV or monitor are damaged.

This could also be a significant decrease in the brightness of the image displayed on the LCD screen and or a breakdown of the decoder. Very often, LCD TVs require repair due to the appearance of “broken” pixels on the LCD screen (their color does not change).

In such cases, it is necessary to completely replace the LCD matrix, which is quite expensive and, in some cases, comparable in price to buying a new TV. When choosing a TV, you need to know that the image quality of LCD TVs practically does not depend on the type of matrix. And their repair, in the event of a breakdown, is practically no different.

“Snow” (noise) appears on the screen. Check the antenna. If everything is fine with it, then the tuner or radio channel may be faulty;

Simultaneous loss of image and sound. Possible reason: the radio channel (video processor and tuner) is faulty;

Only the image is missing (there is sound). In this case, the color unit or video amplifier may have failed;

The loss of sound when saving an image tells us that there may be a malfunction of the sound processor or low-frequency amplifier (LFA);

When the TV is running, we have a horizontal stripe on the screen or the dimensions of the screen and the image do not match - most likely the frame scanning has failed. (cause of occurrence - frequent power surges in the network);

A failed horizontal scan transformer will indicate this by narrowing the image from top to bottom and the presence of a vertical stripe on the screen; Malfunctions in the video amplifier or video processor manifest themselves in the loss of any color or, conversely, in a complete one-color fill of the entire screen.

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A condition that ensures long-term operation (without breakdowns) of an LCD TV is caring for it and following the recommendations set out in the technical documentation.

To prevent possible breakdowns, LCD TVs must be turned on and off with a delay of at least 15 seconds. So, there are many reasons for this defect - from the power supply to the matrix itself. If you do not have the skill to repair such equipment, it is better to contact an authorized service center. All details of the repair are recorded in the video below:

Do-it-yourself repair of an LCD or plasma TV if there is no picture, but there is sound. Repair details

Types of breakdowns

If there is sound, but the TV does not show (there is no image), then something strange may be happening on the screen:

· the screen may become one color;

· the image is compressed into a narrow strip;

· the picture suddenly starts blinking;

· the picture is there, but it’s almost invisible;

· There are ripples on the screen.

Why is there sound but no picture?

When there is no picture, but there is sound, most likely the inverter is faulty or there is a problem with the backlight lamps themselves. The screen may go dark due to a malfunction of other components.

When an LCD TV has sound but no picture, in 90% of cases repairing the power supply or inverter will help.

Of course, the easiest way is to immediately pick up the phone and call a TV repairman. All you need to tell him is the address, time of desired arrival and information about the breakdown. It is also necessary to inform him that there is sound, but no image. Don’t worry, because you have witnessed a very common type of malfunction in many LCD TVs and monitors. Although the very statement about the complete absence of an image is not entirely true. There are types of failures depending on the degree of damage to the block diagrams. For example, when the picture narrows to a strip (after turning on, or after a malfunction), or when the screen glows white, red, green. Occasionally, such malfunctions provoke ripples on the display, flickering of colors, blurring of brightness and contrast.

The inverter in the TV is a device for starting and fluorescent lamps for backlighting the LCD panel. Ensures the constant glow of these light sources for a long time and effectively controls their brightness. It can be made in the form of one or two separate blocks (master/slave), and also located together with the power supply on a single board. When repairing a television receiver inverter yourself, you need to know the functions it performs.

Tasks of the television inverter:

o conversion of direct voltage 12 - 24 volts into high-voltage alternating

o stabilization and adjustment of lamp current

o backlight brightness adjustment

o providing protection against overloads and short circuits

Electrical circuit of a simple inverter for 2 backlight lamps

The device is implemented on a PWM controller U1 (OZ960), two assemblies of field-effect transistor switches (u1, u2) and high-voltage transformers T1, T2. Through connector CN1, 12 volt power (F1), a power command (ON/OFF), and constant voltage (Dimm) are supplied to adjust the brightness. The protection unit (D2, D4, D5, D6) analyzes the current or voltage at the output of the device and generates overload and feedback voltages (OS) supplied to the PWM. If one of these voltages exceeds the threshold value, the self-oscillator at U1 is blocked, and the inverter will be in a protection state. The node is blocked when the supply voltage is low, when the supply voltage “drops” when the load is turned on, when the converter is overloaded or there is a short circuit.

Characteristic signs of inverter malfunction

· Backlights do not turn on

Backlights turn on and off briefly

· Unstable brightness and screen flickering

· The inverter periodically does not turn on after a long period of inactivity

· Uneven screen illumination with 2-inverter circuit

Features of inverter unit repair

When diagnosing faults related to the correct operation of the inverter, you should first of all make sure that there is no ripple in the supply voltage and that it is stable. Pay attention to the passage of startup commands and backlight brightness control from the motherboard. Eliminate the influence of backlight lamps by using their equivalent in cases where the problem is not clear. Take advantage of the opportunity to remove protection from the inverter during repairs to determine the defective part. Don’t forget about a careful visual inspection of the board and what every professional TV technician uses when repairing TVs at home - measuring voltage, resistance, capacitance using special instruments or a tester.

Sometimes, upon careful inspection of the board, you can see “burnt out” parts that need to be replaced. Very often field-effect transistor switches fail, but sometimes replacing them does not always lead to a positive result. The functionality of the unit may be restored for an indefinite period of time, and then the malfunction may occur again. You have eliminated the effect, but not the cause. Therefore, without knowing the intricacies of repairing these devices, you can lose a lot of time and effort to restore them. And, if you have doubts about the success of the matter, call a technician who has already repaired similar devices many times and knows all the “pitfalls and shoals” thanks to his accumulated experience and professional knowledge.

High-voltage transformers are considered the weak link in the inverter units. Operation under high voltage conditions requires special assembly quality of these components and places high demands on the insulation properties. In addition, it should be said that transformers can become noticeably heated during operation of the backlight. Defects such as a break or inter-turn short circuit of the windings of these parts are commonplace. Diagnostics of these elements can be complicated by the fact that a short circuit or break can only be observed in operating mode, and “diagnosis” of them in a de-energized state will not reveal problems with them. Here, swapping the dubious and serviceable transformer and further analyzing the situation can come to the rescue.