Monday 24 February 2020

REPAIR / SERVICING TV LG 42LA645V

Technical description and composition of the LG 42LA645V TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 42LA645V 42LA645V-ZC.BRUYLJU
Chassis / Version: LD33B / LC33B / LE33B
Panel: LC420EUN (SF) (F3)
LED backlight: 6922L-0062A, 6020L-0001C
T-CON: LC470EUN-SFF1 6870C-0432A
LED driver (backlight): 3PHCC20006C-H 6917L-0119C PCLF-D202
Power Supply (PSU): EAX64908001 (1.9 LGP3942-13P
PWM Power: FSD106LG, R2A20133DSP (PFC), L6544AD
MOSFET Power: TK8P60V, MBR10U100CT
MainBoard: EAX64797003 (1.2) EBR76823103
IC MainBoard: CPU: LGE2122, NAND: SAA36403538 VER. 3.20.33, H5TQ4G63AFR, H5TQ2G63AFR, NTP7513
Tuner: TSQ-G601D (B) EBL61240503
Control: Remote: AKB73756502, WIFI: TWFM-B006D EAT61813901
Specifications 42LA645V
LG 42LA645V
General repair guidelines for TV LCD LED
Possible manifestations of defects
- The LG 42LA645V TV does not turn on, does not respond to the remote control and the control panel buttons, the indicators do not light or flash.
Failure in such cases should begin to be sought in the power supply circuits of the EAX64908001. It is necessary to measure its output voltages, and if they are absent, check the operability of power switches (TK8P60V, MBR10U100CT) of converters and rectifier diodes for a short circuit probability.
In the event of breakdowns in the secondary circuits of the converter, it can usually fail in short circuit mode, and in the event of a short circuit in the power elements of the primary circuit, the mains fuse or current sensor at the source of the key most often breaks.
Breakdown of power switches (MosFet) in pulsed sources is sometimes caused by malfunctions of other circuit elements, for example, in circuits supplying a PWM controller, frequency-setting or damper ones, as well as in negative feedback (OOS) stabilization circuits. PWM controllers (PWM) FSD106LG, R2A20133DSP (PFC), L6544AD, if they do not have visible damage to the case and open fault between the terminals, are usually checked by replacement.
- There is no image, there is sound, it responds to the remote control, the channels are switched. In some cases, the image appears when you turn on and immediately disappears.
In most of these cases, a malfunction is detected in the nodes and backlight elements of the LED panel. The reason can be both in the power supply of the LEDs, in their serviceability (breakdown or breakage), as well as in the violation of the contact connections of the LED strips.
To check the LED lines for breaks without disassembling the panel, for example, a current source will help. It is impossible to open series-connected PN junctions with a simple multimeter, a voltage of the order of several tens of volts is required.
- The indicator blinks or lights constantly, the TV does not turn on, does not respond to the remote control.
Repair or diagnostics of the EAX64797003 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). Sophisticated MB board repair (SSB) is in some cases possible and practiced by repairmen. To do this, check and, if necessary, replace the CPU elements: LGE2122, NAND: SAA36403538 VER. 3.20.33, H5TQ4G63AFR, H5TQ2G63AFR, NTP7513. BGA chip malfunctions are usually easy to detect by warming up.
Before changing the tuner TSQ-G601D (B) EBL61240503, if it is not possible to tune to television channels, make sure that there are supply voltages that need to be measured on the corresponding terminals of the tuner and check the software for correctness. The pulses of the data exchange of the tuner with the processor can be controlled by an oscilloscope
Attention to users! Self-repair of the LG 42LA645V TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!


Schematic diagram ------------>  LG CHASSIS LD33B; MODEL 42LA64**, 42LA64**-Z*

 The appearance of the MainBoard EAX64797003 is shown in the figure below:
EAX64797003
EAX64797003 can be used in TVs:
LG 42LA620V (Panel LC420DUE (SF)(U1)), LG 32LN570V (Panel LC320DUE (SF)(R1)), LG 50LA644V (Panel LC500EUN (SF)(F1)), LG 47LA660V (Panel LC470EUG (PF)(F1)), LG 47LA621V (Panel LC470DUE (SF)(U1)), LG 42LA644V (Panel LC420EUN (SF)(F2)), LG 39LA620V ZA (Panel T390HVJ01.0), LG 42LA621V ZD (Panel LC420DUE (SF)(U1)), LG 32LA621V ZD (Panel LC320DUE (SF)(U1)), LG 32LN655V (Panel LC320EUB (PF)(M1)), LG 42LA667V (Panel LC420EUH (PF)(P1) ), LG 47LN613V (Panel LC470DUE (SF)(R4)), LG 32LA667V ZB (Panel LC320EUB (PF)(P1)), LG 55LA660V ZA (Panel LC550EUH (PF)(P1)), LG 47LA620V ZA (Panel LC470DUE (SF)(U1)), LG 32LN613V ZB (Panel LC320DUE (SF)(R4)), LG 42LN655V ZB.BRUZLJU (Panel LC420EUH (PF)(M1)), LG 32LA644V ZA (Panel LC320EUN (SF)(F1)), LG 42LN613V (Panel LC420DUE (SF)(R4)), LG 47LA690V ZB (Panel LC47EUH (PF)(P1)), LG 47LA662V (Panel LC470EUG (PF)(F1)), LG 42LA645V 42LA645V-ZC.BRUYLJU (Panel LC420EUN (SF)(F3)), LG 32LA660V (Panel LC320EUB (PF)(P1)), LG 47LA644V 47LA644V-ZA (Panel LC470EUN (SF)(F2)), LG 50LA667S (Panel T500HVD02.1), LG 47LA691V (Panel LC470EUH (PF)(P1)), LG 32LA662V (Panel LC320EUB (PF)(P1)).
The appearance of the power supply
Main features of the device LG 42LA645V:
Installed matrix (LED panel) LC420EUN (SF) (F3).
The matrix control uses the Timing Controller (T-CON) LC470EUN-SFF1.
The LED driver 3PHCC20006C-H is used to power the backlight LEDs.
The necessary supply voltages for all nodes of the LG 42LA645V TV are generated by the EAX64908001 power supply module or its analogs using FSD106LG, R2A20133DSP (PFC), L6544AD microchips and TK8P60V, MBR10U100CT power switches.
MainBoard - the main board (motherboard) is an EAX64797003 module using CPU chips: LGE2122, NAND: SAA36403538 VER. 3.20.33, H5TQ4G63AFR, H5TQ2G63AFR, NTP7513 and others.
The tuner TSQ-G601D (B) EBL61240503 provides the reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUN-SFF3
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: IPS, Normally Black, Transmissive
Active Area: 927.94x521.96 mm
Surface: Antiglare (Haze 1%), Hard coating (2H)
Brightness: 350 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6 (G to G)
Frequency: 60Hz
Lamp Type: WLED Embedded (LED Driver)
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V