Technical description and composition of the LG 42LA691V TV, panel type and applicable modules. The composition of the modules.LG LED
Model: 42LA691V -ZA
Chassis / Version: LD33B
Panel: LC420EUH PFP1
LED backlight: 6920-0001C 2 * 57 led; cool: 6922L-0072A
LED driver (backlight): integrated into PSU
PWM LED driver: R5F100BCAFP, IW7011
MOSFET LED driver: TK15A20D
Power Supply (PSU): PLDF-L211A LGP4247-LSLP
PWM Power: SSC9527S (PWM), R2A20133D (PFC), ICE3BR4765JZ (Stb)
MOSFET Power: 13NM60N, 10NM60N
MainBoard: NC4_M_TU24
IC MainBoard: IPS6578, 64327 (8)
Tuner: TDSQ-G601D (B)
Specifications 42LA691V
LG 42LA691V
General repair guidelines for TV LCD LED
Repair of the LG 42LA691V-ZA TV is advisable to start with a careful external examination of both internal and external elements. Using visible changes in the state of components, it is usually possible to determine the further direction of troubleshooting and localization of the defect before the necessary measurements are taken. Elements with visible damage, for example, capacitors swelled up after boiling the electrolyte, charred resistors in certain nodes of the circuit, as well as ring cracks in solders will help the master to guess the causes and possible consequences of the malfunction.
In cases where the LG 42LA691V TV does not turn on, does not respond to the remote control and buttons, no indicators on the front panel light up or blink, and there are no sounds and no signs of operability when turning on, the LGP4247-LSLP, PLDF power supply module is most likely faulty -L211A or there is no processor power on the motherboard (a typical defect of some LG TVs). When diagnosing and repairing the power supply, after replacing the swollen capacitors of the filters of the secondary rectifiers (if any), you must first check 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 PWM controller chip are subject to verification, which it is desirable to verify by replacement.
If the LG 42LA691V TV does not have an image, but there is sound, a malfunction in the LED backlight circuits of the LC420EUH PFP1 panel is likely. It is also necessary to check the serviceability of the electrolytic capacitors of the filter of the secondary rectifiers of the PSU (power supply) for an overstated ESR.
Often there is a need for disassembling the panel to check the health of the LEDs, as well as contact connections in the connectors and soldering.
To detect a break in the LED lines without disassembling the panel, a current source is required. It is impossible to open transitions connected in series with a simple multimeter; voltage of several tens of volts is necessary.
Diagnosis and repair of the NC4-M-TU24 motherboard is carried out by checking the performance of the stabilizers or power converters of the module chips. In some cases, a software update is required.
Board repair and replacement of IPS6578, 64327 (8) microcircuits are carried out in the presence of the necessary equipment, and the corresponding element base. Faults associated with the application of BGA processor soldering technologies can be localized by the heating method.
If there is no reception of television channels, but the TV is working properly from external devices, first of all it is necessary to check the voltage of the varicaps of the tuner TDSQ-G601D (B), which is usually within 30-33V, as well as other supply voltages at the terminals of the tuner.
Once again, remind users! Attempts to self-repair the LG 42LA691V TV without the appropriate qualifications and experience can lead to its complete non-repairability!
Schematic diagram ------------> LG 42LA69**, 42LA69**-Z* Chassis LD33B
The appearance of MainBoard NC4_M_TU24 is shown in the figure below:NC4_M_TU24
NC4_M_TU24 can be used in TVs:
LG 42LA691V -ZA (Panel LC420EUH PFP1), LG 32LB582V ZG (Panel LC320DUE (FG) (A4)).
The appearance of the power supply
Main features of the device LG 42LA691V:
Installed matrix (LED panel) LC420EUH PFP1.
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by a PWM controller R5F100BCAFP, IW7011. As the power elements of the LED driver, keys of the TK15A20D type are used.
The necessary supply voltages for all nodes of the LG 42LA691V TV are generated by the PLDF-L211A power supply module or its analogs using SSC9527S (PWM), R2A20133D (PFC), ICE3BR4765JZ (Stb) microcircuits and 13NM60N, 10NM60N power switches.
MainBoard - the main board (motherboard) is an NC4_M_TU24 module, using IPS6578, 64327 (8) microcircuits and others.
The TDSQ-G601D (B) tuner allows you to receive television programs and tune to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC420EUH-PFP1
Type: a-Si TFT-LCD, Panel
Diagonal size: 42 inch
Resolution: 1920x1080, FHD
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 927.94x521.96 mm
Surface: Antiglare (Haze 1%), Hard coating (2H)
Brightness: 400 cd / m²
Contrast Ratio: 1400: 1
Display Colors: 16.7M / 1.06B (8-bit / 8-bit + Dithering), CIE1931 68%
Response Time: 8/10 (Tr / Td)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V