Saturday, 29 February 2020

REPAIR / SERVICING TV LG 42SL8000

Technical description and composition of the LG 42SL8000 TV, panel type and applicable modules. The composition of the modules.
LG
Model: 42SL8000
Chassis / Version: LD91K
Panel: LC420WUD (SB) (M4)
Inverter (backlight): KLS-42SNFSC (E) -A REV: 05
PWM Inverter: BD9897FS
Power Supply (PSU): LGP4247-09S - EAY58470001
PWM Power: R2A20112 (PFC), L6599 (PWM), VIPer27H (Standby)
MainBoard: EAX60890803 (3)
IC MainBoard: CPU: XD ENGINE LGF7329A-LF / XD ENGINE LGE3369A-LF-SF, Spi Flash: 25X32VSIG, HYB18TC1G160C2F, SOUND: NTP-3100L
Tuner: TDVW-H103F
Appearance
LG 42SL8000
General recommendations for repairing TV LCD
Repair of TVs, as well as other devices, it is advisable to start with an external examination. Specific external damage to some elements can sometimes indicate further actions to determine the malfunction of the TV and localize the defect before the necessary measurements are taken. If charred resistors, swollen electrolytic or cermet capacitors, ring cracks in the solders of the terminals of transformers or heating elements are found, it is advisable to establish the causes and consequences of the malfunction that has arisen, as well as to check the connected elements and assemblies.
The malfunction of the power supply is often manifested corny - the TV does not turn on, does not make any sounds, does not light and does not blink with any indicators. It is advisable to start the troubleshooting of the power supply module by checking the state of the electrolytic capacitors of the rectifier filters and the mains fuse. Defective capacitors should be replaced. If the mains fuse is broken, it is necessary to check first of all the power semiconductor elements - rectifier diodes and transistors, which are often found in such a state of breakdown.
It should be borne in mind that in the practice of repair it is extremely rare that key transistors in switching power supplies (SMPS) fail for no reason that should be sought by checking other components, for example, a breakdown of the key can provoke faulty elements of the damper circuits, or dried electrolytic capacitors or dangling primary resistors BP circuits involved in the stabilization process. In this case, all semiconductor elements of the strapping of the PWM regulator chip R2A20112 (PFC), L6599 (PWM), VIPer27H (Standby), which it is desirable to check by replacement, are subject to verification.
If the LG 42SL8000 does not have an image, there is sound and the channels are switched, there is a possibility of a malfunction of the display backlight, or their power converter - inverter. Sometimes when you turn on the image appears and disappears immediately. In such cases, it is necessary to check the electrolytic capacitors of the power filter of the inverter itself, including in the secondary rectifier of the main PSU. Turning off the protection for diagnostic purposes, it must be remembered that in this case there is a risk of failure of the power elements of the inverter. Upon completion of the diagnosis, all regular protection circuits should be restored.
Diagnosis and repair of the EAX60890803 (3) motherboard usually begins with a test of the performance of the stabilizers and power converters of the module chips. In some cases, a software update is required. Sophisticated MB board repair (SSB) is in some cases possible and practiced by repairmen. To do this, check and, if necessary, replace the elements Cpu: XD ENGINE LGF7329A-LF / XD ENGINE LGE3369A-LF-SF, Spi Flash: 25X32VSIG. BGA chip malfunctions are usually easy to detect by warming up.

Attention to users! Self-repair of the LG 42SL8000 TV without the appropriate qualifications and experience can lead to its complete non-repairability!


SCHEMATIC DIAGRAM ----------->  LG LD91K 42SL8000



 The appearance of the MainBoard EAX60890803 is shown in the figure below:
EAX60890803
EAX60890803 can be used in TVs:
LG 42SL8000 (Panel LC420WUD (SB) (M4)), LG 37SL8000 (Panel LC370WUD (SB) (M3)).
The appearance of the power supply
Main features of the device LG 42SL8000:
Installed matrix (LCD panel) LC420WUD (SB) (M4).
To power the backlight, an inverter KLS-42SNFSC (E) -A is used, it is controlled by the BD9897FS PWM controller.
The necessary supply voltages for all nodes of the LG 42SL8000 TV are generated by the LGP4247-09S power supply module or its analogs with the use of R2A20112 (PFC), L6599 (PWM), VIPer27H (Standby) microcircuits.
MainBoard - the main board (motherboard) is an EAX60890803 module using Cpu chips: XD ENGINE LGF7329A-LF / XD ENGINE LGE3369A-LF-SF, Spi Flash: 25X32VSIG, HYB18TC1G160C2F, SOUND: NTP-3100L and others.
The TDVW-H103F tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420WUD-SBM4
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: 600 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M / 1.06B (8-bit / 8-bit + Dithering)
Response Time: 6 (MPRT)
Frequency: 120Hz + 120Hz
Lamp Type: CCFL Embedded (Inverter)
Signal Interface: LVDS (4 ch, 8/10-bit), 96 pins
Voltage: 12.0V