Technical description and composition of the LG 42LB552V TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LB552V ZA
Chassis / Version: LC43B / LD43B / LB43T
Panel: LC420DUE (FG) (A6)
LED backlight: LG Innotek DRT 3.0 42_A type / 42_B type Rev01
T-CON: 6870C-0480A V14 42 DRD 60Hz Control_Ver 0.3
LED driver (backlight): integrated into PSU; 208V 250mA
PWM LED driver: BD9486F
MOSFET LED driver: MDD3752, MDHT4N20Y
Power Supply (PSU): EAX65423701 (2.0)
PWM Power: MAP8800 (PFC), FA6A01N (PWM resonant)
MOSFET Power: MMP60R360P (PFC), 10N60 * 2
MainBoard: EAX65388006 (1.0)
IC MainBoard: CPU: LGE2134; SPI Flash: MX25L8006E; SOUND: TAS5733
Tuner: TDJM-G101D
Control: AKB73715679; IR: EBR78480602
Specifications 42LB552V
LG 42LB552V
General repair guidelines for TV LCD LED
In cases where the LG 42LB552V TV does not turn on, does not respond to the remote control and buttons, no indicators on the front panel light or blink - most likely the EAX65423701 power supply module is faulty or there is no standby power. When diagnosing and repairing the power supply, after checking the electrolytic capacitors of the filters of the secondary rectifiers, it is necessary first of all to pay attention to the mains fuse. When it is broken, the power elements of transistors and rectifier bridge diodes should be checked for avalanche (thermal) 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 MAP8800 PWM controller chip are subject to verification, which it is desirable to verify by replacement.
In this model, the power module includes a backlight LED power converter - Led-driver, made on the BD9486F PWM controller, which is a LED current stabilizer and is a Step-Up-Converter.
If the LG 42LB552V does not have an image, but there is sound and the TV is controlled by the remote control, there may be a malfunction in the backlight circuits of the LC420DUE (FG) panel (A6). LEDs or power converter - Led-Driver may be faulty. Often in such cases, when you turn on the TV, an image appears and immediately disappears. First of all, it is necessary to verify the operability of the electrolytic capacitors of the power filters, and check the LEDs with a current source or by connecting obviously known good diagnostics.
To check the health of the LEDs, as well as contact connections in the ruler circuit, it is necessary to disassemble the panel.
It is impossible to check the line of series-connected LEDs without a special current source, and for this purpose it is not safe to use any voltage sources above 12V. Often you need to open the panel and check each LED separately.
It is necessary to distinguish between LEDs with one P-N junction (unlock voltage of about 3V) and two transitions, the unlock voltage of which is twice as large, about 6 volts.
When trying to open the LED using low-voltage voltage sources even with the use of limiting resistors, there is a risk of accidentally reversing the polarity and opening the protective zener diode in the forward direction. The breakdown of the zener diode in this case will require the replacement of LEDa.
Repair or diagnostics of the EAX65388006 (1.0) motherboard should begin by checking the stabilizers and power converters needed to power the chips and matrix. If necessary, you should update the software (software).
When repairing an MB board, you need to check its CPU components: LGE2134; SPI Flash: MX25L8006E; SOUND: TAS5733. Defective items should be replaced. If BGA chips are installed, their malfunction is usually localized by heating.
If the TV works normally from external devices, but does not tune into television channels, the TDJM-G101D may be malfunctioning. In such cases, first of all, you should make sure that there are supply voltages at its corresponding terminals and check the data exchange with the processor using an oscilloscope. Sometimes the cause of the inoperability of the tuner may be a software failure.
Remember! Attempts to self-repair by users of the LG 42LB552V TV without the appropriate qualifications and the necessary experience can lead to serious negative consequences!
Backlight Current Limit:
In televisions with power supplies LGP3942-14PL1 (EAX65423701), the backlight current sensor - the resistor block R811-R818 consists of four pairs of 4.3 Ohm each. You can reduce the backlight current by 25% by removing one pair of resistors.
Schematic diagram ------------> LG CHASSIS: LD43B/LD44B MODEL: 42LB55** 42LB55**-Z* 42LB552V 42LB552V-TB.
The appearance of the MainBoard EAX65388006 is shown in the figure below:EAX65388006
EAX65388006 can be used in TVs:
LG 32LB561V (Panel LC320DUE), LG 32LB561U (Panel NC320DXN VSBP1), LG 42LB629V ZM (Panel LC420DUE (FG)(P2) ), LG 32LB563U (Panel NC320DXN VSBP1), LG 42LB552V ZA (Panel LC420DUE (FG)(A6)), LG 32LB552U (Panel NC320DXN-VSBP4), LG 32LB563V (Panel LC320DUE (FG)(A3)), LG 42LB561V ZE (Panel LC420DUE (FG)(A3)), LG 42LB569V 42LB569V-ZX.BRUWLDU (Panel LC420DUE (FG)(A3)).
PSU Advanced
The 42LB552V model uses the EAX65423701 power supply unit using the PFC (Power Factor Correction) node - an active filter of the highest harmonics of the current consumption. In fact, this is a boost converter based on the MAP8800 PWM controller, which eliminates the charge current of the electrolytic capacitor of the rectifier filter directly from the network through open diodes, when its charging current is determined by its reactance.
As a result of the operation of the converter, the envelope of the high-frequency pulses of the input current of the converter will repeat the shape and phase of the input voltage. The health of the PFC node can be indirectly judged by the presence of an increased constant voltage (about + 380V) on the capacitor of the rectifier network in operating mode.
The appearance of the power supply
Main features of the device LG 42LB552V:
Installed matrix (LED-panel) LC420DUE (FG) (A6).
The matrix control uses the Timing Controller (T-CON) 6870C-0480A.
To power the backlight LEDs, a converter is used, combined with a power supply, controlled by the BD9486F PWM controller. As power elements of the LED driver, keys of the type MDD3752, MDHT4N20Y are used.
The necessary supply voltages for all nodes of the LG 42LB552V TV are generated by the EAX65423701 power module or its analogs using MAP8800 (PFC), FA6A01N (PWM resonant) microcircuits and power switches of the MMP60R360P (PFC) type, 10N60 * 2.
MainBoard - the main board (motherboard) is an EAX65388006 module, using CPU chips: LGE2134; SPI Flash: MX25L8006E; SOUND: TAS5733 and others.
The TDJM-G101D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC420DUE-FGA6
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 (3H)
Brightness: 300 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (8-bit), CIE1931 68%
Response Time: 6 (G to G)
Frequency: 60Hz
Lamp Type: WLED Without Driver
Signal Interface: LVDS (2 ch, 8-bit), 51 pins
Voltage: 12.0V