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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Thursday, 27 February 2020

REPAIR / SERVICING TV LG 42LE7500

Technical description and composition of the LG 42LE7500 TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LE7500
Chassis / Version: LD03E
Panel: LC420EUH (SC) (A2)
T-CON: integrated into MainBoard
LED driver (backlight): integrated into PSU; 118V 660mA (42 inch LG)
PWM LED driver: AS3693B, MEGA48PA
Power Supply (PSU): PLDF-L903A EAY60803101
PWM Power: VIPER27H (Standby), ICE2PCS04 (PFC), L6599D
MOSFET Power: TK4P60DB
MainBoard: EAX61742605 (2) EBU60866721 // EAX61742608 (1) EBT60944301
IC MainBoard: LGE3556C, EPROM: 24512, W25X40 sticker: SAA35063405 V1.50 DD11, 24C16, NTP-7100
Tuner: TDFR-G055D
Specifications 42LE7500
LG 42LE7500
General repair guidelines for TV LCD LED
If the LG 42LE7500 TV does not turn on, no control lights are on or blinking, there are no sounds when you turn on, there is not the slightest sign of operability - the most likely malfunction is in the power module.
If the mains fuse is cut off, in most cases a breakdown of the power switches is detected, which can be integrated with the PWM controller. The rectifier bridge diodes and the electrolytic capacitors of the mains rectifier filter should also be checked.
LED driver - the power converter of the panel backlight LEDs is a step-up voltage converter with stabilization of the current in the load and is part of the PSU PLDF-L903A general power supply module.
Sometimes the LG 42LE7500 TV does not have an image, but there is sound, or the image appears and immediately disappears. In this case, there is a high probability of a malfunction of the LED driver, or a break in the LED circuit is possible. In such cases, first of all, it is necessary to verify the operability of the electrolytic capacitors of the filter according to the driver power supply.
A malfunction in the backlight circuits often occurs due to an open in the power circuit of the LED lines. It is necessary to disassemble the panel and check the LEDs themselves, the soldering of their conclusions, as well as the reliability of the connections in the connectors and the soldering of the conclusions of the connectors.
When diagnosing, it is necessary to take into account that it is impossible to check the open in the chain of LED lines without disassembling the panels using a tester or multimeter. To open all PN junctions connected in series, a voltage of the order of several tens of volts is required, and ideally, a current source.
In cases of attempts to repair the motherboard EAX61742605, it is necessary to check the operation of linear stabilizers and power converters of its microcircuits and, if possible, update the software (software). BGA chips can sometimes be diagnosed with local heating.
In cases of attempts to repair the MB (SSB) board, it is necessary to check the health of its elements - LGE3556C, W25X40, 24C16 which may require replacement with new ones. If a BGA processor is installed, there is a possibility of a violation of the soldering of the contacts of its conclusions with the board (it is diagnosed by heating).
Before replacing the TDFR-G055D tuner, if there is no tuning for the channels, you must first check the software and the supply voltage at its terminals, as well as trace the data exchange of the tuner and processor via the I2C bus using an oscilloscope.
Attention to the owners! Attempts at self-repair of the LG 42LE7500 TV are not recommended by the manufacturer and can lead to serious negative consequences!
Typical defects of LG TVs with LGE3556C processors are provoked by its severe temperature conditions and the quality of the LGE3556C processor itself.
External manifestations may be different - the tuner or external inputs do not work, or the TV does not turn on, for example, the control lamp blinks or hangs on the screen saver.
If, when the processor warms up, performance is restored, in such cases a reball can sometimes help. Then there is the opportunity to extend the life of the TV with the help of an additional heat sink or cooler. When replacing the processor, it should be borne in mind that they are discontinued and all LGE3556C, which sellers ALIexpress send, in most cases control units, are often already faulty.


SCHEMATIC DIAGRAM --------->  LG CHASSIS LD03E MODEL: 42LE7500, 42LE7500-ZA


 The appearance of the MainBoard EAX61742605 is shown in the figure below:
EAX61742605
PSU Advanced
The 42LE7500 TV is equipped with a PLDF-L903A power module using the PFC (Power Factor Correction) circuitry acting as an active filter to eliminate the higher harmonic components of the current consumption. The boost converter based on the ICE2PCS04 PWM controller does not allow the input rectifier filter's electrolytic capacitor to be connected to the network directly through open diodes when the charge current determines its reactance (about 15-30 ohms at a frequency of 50 Hz). As a result of the conversion, the charging current of the capacitor will be determined in such a way that the envelope of the high-frequency pulses of the input current will repeat the phase and shape of the sine wave of the input voltage. The health check of the PFC unit is carried out by measuring the DC voltage on the capacitor of the rectifier network. In operating mode, it should be around 380V, in standby approximately 300V.
The appearance of the power supply
Main features of the device LG 42LE7500:
Installed matrix (LED-panel) LC420EUH (SC) (A2).
The matrix control uses the Timing Controller (T-CON) integrated.
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by a PWM controller AS3693B, MEGA48PA.
The necessary supply voltages for all nodes of the LG 42LE7500 TV are generated by the PLDF-L903A power supply module or its analogs using VIPER27H (Standby), ICE2PCS04 (PFC), L6599D microcircuits and TK4P60DB type power switches.
MainBoard - the main board (motherboard) is an EAX61742605 module, using LGE3556C chips, EPROM: 24512, W25X40 sticker: SAA35063405 V1.50 DD11, 24C16, NTP-7100 and others.
The TDFR-G055D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUH-SCA2
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 930.24x523.26 mm
Surface: Antiglare (Haze 10%), Hard coating (3H)
Brightness: 450 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 1.06B (8-bit + Dithering), CIE1931 72%
Response Time: 8/10 (Tr / Td)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: Mini LVDS, 120 pins
Voltage: 12.0V
 
Posted By: FRANK at 05:51
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