REPAIRING AND NOT THROWING AWAY

REPAIRING AND NOT THROWING AWAY

Richtige Fernseher haben Röhren!

Richtige Fernseher haben Röhren!

In Brief: On this site you will find pictures and technical information about Service Modes, Circuit Diagrams, Firmware Update procedure, Disassemble procedure, Universal remote control set-up codes, Troubleshooting and more....

If you go into the profession, you will obtain or have access to a variety of tech tips databases HERE IT IS Master Electronics Repair !.

These are an excellent investment where the saying: 'time-is-money' rules. However, to learn, you need to develop a general troubleshooting approach - a logical, methodical, method of narrowing down the problem. A tech tip database might suggest: 'Replace C536' for a particular symptom. This is good advice for a specific problem on one model. However, what you really want to understand is why C536 was the cause and how to pinpoint the culprit in general even if you don't have a service manual or schematic and your tech tip database doesn't have an entry for your sick TV or VCR.

While schematics are nice, you won't always have them or be able to justify the purchase for a one-of repair. Therefore, in many cases, some reverse engineering will be necessary. The time will be well spent since even if you don't see another instance of the same model in your entire lifetime, you will have learned something in the process that can be applied to other equipment problems.
As always, when you get stuck, checking out a tech-tips database may quickly identify your problem and solution.In that case, you can greatly simplify your troubleshooting or at least confirm a diagnosis before ordering parts.

Happy repairing!
Today, the West is headed for the abyss. For the ultimate fate of our disposable society is for that society itself to be disposed of. And this will happen sooner, rather than later.

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..............The bitterness of poor quality is remembered long after the sweetness of todays funny gadgets low price has faded from memory........ . . . . . .....
Don't forget the past, the end of the world is upon us! Pretty soon it will all turn to dust!

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Tuesday, 3 March 2020

REPAIR / SERVICING TV LG 49LH520V

Technical description and composition of the LG 49LH520V TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 49LH520V
Chassis / Version: LD67C
Panel: LC490DUE (FJ) (A1)
LED backlight: 6916L-2709A & 6916L-2710A
T-CON: 6870C-0532C
LED driver (backlight): integrated into MainBoard
PWM LED driver: MP3378E
MOSFET LED driver: AOD2922
Power Supply (PSU): Adapter 19V 3.42A
MainBoard: EAX66805906 (1.0)
IC MainBoard: LGE6351, H27U1G8F, MX25L8035E, DT1803A, SN1406035, NTP7515
Tuner: TDJA-G301D
Control: AKB74476490
Specifications 49LH520V
LG 49LH520V
General repair guidelines for TV LCD LED
Possible malfunctions
- The LG 49LH520V TV does not turn on, does not respond to the remote control and buttons on the control panel, does not light up or blink indicators.
Most often, with such manifestations, the main adapter power module is found to be faulty.
The external adapter 19V 3.42A power supply is not always subject to repair, especially since the owner can purchase it independently. But, in some cases, it makes sense to open it and eliminate the simple typical defects inherent in converters in pulsed sources. It is necessary to measure the output voltages in its secondary circuits, and if they are completely absent, it is necessary to check the serviceability of power switches and rectifier diodes for possible breakdown (short circuit).
In case of breakdowns of semiconductors in the secondary circuits, the converter can usually work abnormally in the short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse often breaks.
Mos-Fet keys used in switching power supplies usually fail due to a malfunction of other elements that can put it out of operation in key mode or provoke an excess of the maximum current or voltage. These can be circuits supplying the PWM controller, damping or frequency-setting circuits, or elements of OOS (negative feedback) in the stabilization circuit. PWM controllers (PWM), in the absence of external damage and short circuit between the terminals, are checked by replacing with obviously good ones.
- There is no image, there is sound, it is responding to the remote control. Or immediately after turning on for a second, the image may appear and immediately disappear.
In such cases, the most likely malfunction of the LED backlight elements. The reason for this may be a break in the LED circuit, or a problem in stabilizing their power supply.
To check the health in the LED circuit, it is better to use a current source with a maximum voltage of 200V. We do not recommend using any voltage sources for this purpose. You can check each LED individually with a simple Chinese multimeter (powered by 9 volts) in the P-N-junction test mode. If you connect the red probe of the multimeter to the anode of the LED, and the black to its cathode, then the 3-volt LED will light up slightly, and in the opposite direction you can detect the transition of the emergency zener diode. A zener diode PN junction indirectly indicates a LED-a
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the EAX66805906 motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, update or replace the software (software). When repairing an MB board, you need to check its components LGE6351, H27U1G8F, MX25L8035E, DT1803A, SN1406035, NTP7515. Defective items should be replaced. If chips with BGA soldering technology are used, a problem in its implementation is detected by the local heating of the chip.
If a TDJA-G301D tuner is suspected of malfunction, first of all, it is necessary to verify the correctness of the software, as well as the presence of the necessary supply voltage levels and data exchange pulses with the processor via the I2C bus at the corresponding tuner pins.
Once again, remind users! Attempts to self-repair the TV LG 49LH520V without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!
To reduce the backlight current in LED drivers with the MP3378E PWM controller, it is necessary to proportionally increase the total resistance of the resistors from pin 3 (RISET) to the chassis. Calculation of current in milliamperes and resistance in kilo-ohms 977 / Rset for each channel. Parallel channels are summed. For example, for four parallel channels and a RISET 10 KOhm resistance, the total current will be 97.7 * 4 = 391 mA.

 The appearance of the MainBoard EAX66805906 is shown in the figure below:
EAX66805906
EAX66805906 can be used in TVs:
LG 32LH510U (Panel HC320DXN-VSVS1 - 511X), LG 43LH513V (Panel HC430DUN-SLVX1 - 511X), LG 32LH520U (Panel HC320DXN-ABVS2-5112), LG 43LH520V (Panel LC430DUE (FJ)(A1)), LG 32LH513U LG 32LH513U-ZE (Panel HC320DXN-VHVS1-214X), LG 49LH520V (Panel LC490DUE (FJ)(A1)).
Main features of the device LG 49LH520V:
Installed matrix (LED-panel) LC490DUE (FJ) (A1).
The matrix control uses the Timing Controller (T-CON) 6870C-0532C.
To power the backlight LEDs, a converter is used, combined with the EAX66805906 main board, controlled by the MP3378E PWM controller. As power elements of the LED driver, keys of the AOD2922 type are used.
To power all the internal components of the LG 49LH520V TV, an external adapter type 19V 3.42A is used.
MainBoard - the main board (motherboard) is an EAX66805906 module, using chips LGE6351, H27U1G8F, MX25L8035E, DT1803A, SN1406035, NTP7515 and others.
The TDJA-G301D tuner provides TV reception and channel tuning.
Posted By: FRANK at 03:22
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