LG TV troubleshooting

This a good collection of tips on amateur radio professionals for troubleshooting in the LG TVs schemes, enable very fast, and most importantly qualitatively make repairs, even a novice electronics engineer.

troubleshooting in the LG TVs schemes
Troubleshooting in the LG TVs schemes

LG CF21D70. When you turn on the TV, in 2-3 seconds, it goes into standby mode. The reason for the breakdown of the diode 2N4148 (150V) for the D408 scheme. Already 3 cases in 3 months.

GOLDSTAR CKT-4905. TV will not turn on. At the exit instead of the 115 volts - 40. Moreover, the diode voltage is normal, but after the relay 40. The power supply operates without additional overload of sounds. Diode for 115 volts gets very hot. When checking the secondary circuit no suspicious items do not show up. It turned out to be a faulty capacitor S8075 160V \ 33Mkf. Capacity Check on the device showed the presence instead of 33 uF all 0,23Mkf, leakage was 50 th. The defect is very common. Replaced TDKS punched in the TV LG: 154-375F, and then watch a strange effect: the service information (. Number prog, menu lines) twitch vertically 2-3 cm, the main image at the same time is fine if reducing stress SCREEN on TDKS twitching. It stops plot also affects the brightness. It was found that the secondary voltage with TDKS powered overstated personnel - 29v instead of 24v. Put 3 in series in the diode chain and all.

TV LG CF-20D30 when you turn on the power button is blinking LED on the front panel once, and nothing more - the power supply does not start, there is the secondary output voltages. Guilty turned electrolyte trim STRS5707 (standing between the radiator plates STRS-ki, C = 4,7mkf * 50B), which has lost the capacity to 1 uF.

Gold Star (LG) 21D16. Something too clever by half the guys in this model with stereo sound at an extra charge and TDA2009A. In a number of boxes, after half a year of work there is a problem in the form of a raucous (bunch) and a weak sound. The most optimal solution to the problem without replacing the chip resistor was weighed 2 - 3 MW between the input of the first and second channel TDA and + 12V.

Goldstar CB-28C22X. A narrow horizontal strip. Breaking through the 2-24V zener diode, charred R304. After replacing stabilitronov- band left, R304 heats. Replaced O. a. frame. isolator., TDA8350Q- resistor stopped to bask, but the band still. (Need a circuit on hand as always). After analysis of the scheme found that 2 ms personnel comes power: 4 and 8 feet. In conclusion D702 4 broken, FR702 open. After changing the TV worked. (On the Internet, you can dock at TDA8350Q take industrial electronics website.)

V Goldstar CF-21E60B. External fault indication - c / o few minutes after switching on - no picture (screen is dark) and sound in the presence of a raster, there is no response to commands from the remote control (with the TV panel control), and in the future - the failure of video synchronization and spontaneous entrance into standby mode, and after a while the functions are restored, and everything is repeated. Fault - processor LG8534-13A, part of his scheme - analog adjustment switch - off, the instruction decoder control fail at warming. Treatment - a secret |125, causing a layer of CBT and applying a top copper plate on the size of the body, broiled 65-watt soldered before the solder on the wafer has not ceased to solidify (8-15 seconds). The second successful recovery.

LG CF-21K49 on the chassis MC994A. The symptom does not turn on or screen a narrow vertical strip. Replacement likely to be a capacitor C411 334 / 200V.

LG CF-20D30 (Chassis: MC64B). There is no reception on the upper sub-band meter. Fault revealed quite unexpectedly. Summary (on which was a challenge) was: spoiled network switch button (white, expensive 150r.). After replacing the switch and it found that there is no IR sub-band switching voltage (12V instead of only about 5V). switching voltage is supplied through the transistors, a quick test which showed that everything is OK. All round out the how-to on the tuner. But something of this defect I have never met. Doubts were correct. After desoldering stuff around HB tuner output it appeared that transistor Q181 2SA1266 (p-n-p 50V 0.15A) on ohms to call as normal, and has Komakhia R (b-e) arr. = 150kOm. He then planted 12V on the output tuner.

TV LG-CF21D79, oversaturated color image B / W is not as if there is no luminance signal. Replacing the video processor has given nothing TB1238BN. Malfunction was chip SECAM TA1275AZ.


TV LG20 to the MS-84A chassis. The defect can and non-proliferation (met once), but I found it interesting. Slow to respond to commands, poorly configured and does not remember the setting. The service turned out to be all the settings on the zeros, but when you enter the proper initialization mode and out of service, it was the same. Replacing memory has given nothing. It turned out, two of the eight resistors in the assembly, instead of ceramic 4,7kOM ~ 2.4kOm shown. The problem with the chassis LG MC-019A. TV does not come out of standby mode, if the power supply line to measure-about 70 volts. First of all, see C820 220 MF 160 B, often interrupted one of the conclusions of the container, forming conclusions made at a very acute angle.


LG CF-21D70 (Chassis: MC-64A). When you turn on - it goes into standby mode, and then completely extinguished. The analysis showed that the input line voltage, output voltage + B gradually increases to more than 160 in (normal + 125V) and then triggers the internal protection and breaks the generation of PD. Analyzing found defective electrolyte S824 4,7mkF 50B (leakage, desiccation or increase ext. Conjugated. HF), set between 4 CONCLUSIONS. optocoupler IC801 and 7 CONCLUSIONS. STRS5707. What pleases - it is timely self-protection, which is not given to roam murderous + B = 160-180V.

TV Gold Star CF21E20 Chassis MC-41A sound disappeared. Pretty quickly found that the volume control signal is almost zero, otpaivat output adjustment GS8434-16 control processor (3pin) - yelling at the full, in AV mode, too, there is no sound, it would seem all clear, it is necessary to change prots.- not such a rarity. .. But after changing the situation has not changed, flashing a flash drive with a known good, too, failed. I had to start thinking .... I take out antennu- after 10 minutes TV otklyuchaetsya- well it and db I leave with the signal from efira- through the same 10 minutes otklyuchaetsya- clear no SOS signal (herein referred to as the CPU ID- 17pin) - consistently high level. Unfortunately here worked stereotype myshleniya- supplies low on this input, but the situation does not change, and in the mode of video input sound is also not ... In many television processors SOS signal is integrated and measured at the level of, respectively, and trace it with light- failure signal station level changes dramatically. Here impulsnyy- signal pulses are used SSC. The transistor Q06- signal generator ID "drip" transition K-B, the pulses at the input ID no. The SAMSUNG TVs in case of failure "sweet couple" and the protection of the cliff R2M TDKS- punched at the top, near the exit of the high-wire formed Teschin about 5 mm and beat her spark in the core. There was very helpful advice on restoration TDKS- crack at large drill bit to drill a couple of mm in depth and fill with white sealants, after 3 hours, you can include. So obrazom- 2 transformer for the week.


The LG-21D70X when you turn on the TV, switch programs do not store information about settings. After pressing the power button, the TV turns on in LINESVC mode, from which returns to normal mode by pressing the TV / AV button control. After 24S02 memory replacement and turn on the TV once again moved to LINESVC mode, then after pressing the remote control TV / AV button, the TV switched to the normal mode with the restoration of the functions save the settings. No further action by "flashing" the memory chip is not needed.

GoldStar and LG TVs until 2000. Problems with the tuner does not remember settings, etc. It looks like the output of the tuner system. Soldered contacts excavation in tuner.



TV Goldstar CF20A80Y. When the audible sweep operation, but there is no sound and raster. The fault is in m / D402 (7809) produced by KIA. It stands together with the D401 (7812) on one heat sink, near TDKS.


Gold Star CF-29C44 When the TV goes into defense. Replace the board PIP Krenke 78L08 position IC7P number. Almost all the faults in these models are linked to this KPENkoy.


GoldStar CF-21D60B. No sound. I got a 2nd TV with such damage. Faulty audio control output for the 3rd leg LG8434-03C processor. Our processor is ~ 800r. If the client can arrange a sound start to adjust the contrast of the processor. Contrast set the optimum in its sole discretion. The only drawback - the sound adjustment menu.


LG CF-20D60. It does not turn on, as measured in the power supply comes from starting. Needs replacing 4,7mFx50V capacity (located in the alignment of the radiator 5707).


LG CF-21D70 spontaneous transition to standby mode. On different channels in different ways, on one after 5 min after 10 min others. Try replacing the nominal value S408 160V1mF electrolyte gap shrunk to 0 in addition also was a leak.


LG CT-29K37E. When the power supply relaxation in rabochitsy regime enters through 5-6 on-off attempts. The replacement of C808 (100.0x35V) in the power supply, which is assembled on-chip STR-F6656.