Saturday, 15 February 2020

REPAIR / SERVICING TV LG 32LB650V

Technical description and composition of the LG 32LB650V TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 32LB650V ZE
Chassis / Version: LD42B
Panel: LC320DUH (FG) (P2)
LED driver (backlight): integrated into PSU; 117V, 250mA
PWM LED driver: SSC1S311, A27RAE (sot23-6)
MOSFET LED driver: STD11N65M5, STN4NF20L
Power Supply (PSU): LGP32-14PL1 EAX65391401 (2.8)
PWM Power: NCP1251 (PWM SOT23-6 5A2R ..), NR134S
MOSFET Power: KP8N65
MainBoard: EAX65384004 (1.5)
IC MainBoard: CPU: LG1311; DRAM: H5TQ4G63AFR-PBC; EEPROM: AT24C256C, EMMC: THGBMAG6A2JBAIR
Tuner: EBL61400501 TDJM-G101D
Specifications 32LB650V
LG 32LB650V
General repair guidelines for TV LCD LED
LG 32LB650V ZE, like other televisions, it is advisable to start repairing with inspection of external and internal elements and modules. According to some external signs of a change in the state of some elements, it is sometimes possible to make assumptions about the nature of the defect, as well as determine the further direction of the troubleshooting. Swollen electrolytic or cermet capacitors, charred resistors, ring cracks in the soldered terminals of the elements - all this can significantly help the master to determine the causes and consequences of the malfunction of the TV.
If the TV does not turn on, no control lights are on or blinking, there are no sounds when you turn on, and there is not the slightest sign of operability - the most likely malfunction is in the power module. First of all, it is necessary to replace the swollen capacitors of the rectifier filters, if any. If the mains fuse is cut off in the power supply, in most cases a breakdown of the power key (s) is detected, which can be integrated with the PWM controller, or a separate field-effect transistor can be used. The rectifier bridge diodes and the electrolytic capacitor of the mains rectifier filter should also be checked.
Mos-Fet keys used in switching power supplies (SMPS) rarely fail for no reason to look for when checking other circuit elements. Often the breakdown is caused by malfunctions of electrolytic capacitors or semiconductor elements in the primary circuit, or by a break in the resistors in the stabilization circuits. The PWM controller microcircuit SC1S311, 5A2R .. (NCP1251) can also cause a breakdown of the power switch of the converter.
If the LG 32LB650V does not have an image, but there is sound, the LC320DUH (FG) (P2) panel backlight LEDs or their power converter may malfunction.

Often in the absence of backlighting, disassembling the panel is required. It is necessary to check the health of the transitions of the LEDs, as well as the reliability of the contact connections in the lines and connectors.
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 for them. Then it remains only to open the panel and check each LED separately. Usually, Chinese 9V-powered multimeters light up one LED slightly if you connect the probes in the forward direction, the red probe to the anode, and the black to the cathode.
On the EAX65384004 (1.5) motherboard, in case of a malfunction, you should first check the operation of all the stabilizers and power converters of the microcircuits, and also, if necessary, update the software (software).
In cases of attempts to repair the MB board (SSB), it is necessary to check the health of its elements - CPU: LG1311; DRAM: H5TQ4G63AFR-PBC; EEPROM: AT24C256C 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).
In the absence of tuning to local television channels, you should make sure that the software is correct, as well as the presence of supply voltages at the terminals of the tuner EBL61400501 TDJM-G101D.
Attention! For users and owners of 32LB650V TVs who do not have the appropriate qualifications, knowledge and experience, we strongly recommend against attempting self-repair in order to avoid negative consequences that could lead to complete non-repairability of the device.


One of the typical failures of the LG 32LB650V ZE often occurs in the LG panel LC320DUH (FG) (P2).
External manifestations: there is no image, the backlight does not work. In most such cases, the LEDs turn out to be malfunctioning, which during testing turn out to be either in a cliff or with broken internal zener diodes.
LEDs must be replaced, and the maximum current from the driver should be limited to 10-20%.

You can reduce the backlight current in LG TVs with LGP32-14PL1 power supplies (EAX65391401) as follows. The current sensor consists of six resistors R816-R821 connected in parallel - 1 Ohm, 1 Ohm, 1 Ohm, 1 Ohm, 2 Ohm, 8.2 Ohm. The total resistance in this case will be 0.22 Ohm. If you remove one resistor 1 Ohm, the total resistance increases to 0.28 Ohm, the current decreases proportionally from 250 mA to about 190 mA.
More details on this page


SCHEMATIC MANUAL ------------------------>  LG CHASSIS LD42B MODEL: 32LB65** 32LB65**-Z*.


 The appearance of the MainBoard EAX65384004 is shown in the figure below:
EAX65384004
EAX65384004 can be used in TVs:
LG 32LB650V ZE (Panel LC320DUH (FG)(P2)), LG 47LB650V ZE (Panel LC470DUH (FG) (P2)), LG 42LB650V (Panel LC420DUH (FG)(P2)), LG 42LB671V ZF (Panel LC420DUH (PG) (F1)), LG 47LB671V (Panel LC470DUH (PG)(F1)), LG 42LB653V ZK (Panel LC420DUH (FG)(P1)), LG 42LB720V (Panel LC420DUH (PG)(F1)), LG 42LB658V (Panel LC420DUH (FG)(P2)), LG 47LB677V (Panel LC470DUH (FG)(F1)), LG 42LB679V (Panel LC420DUH (PG)(F1)), LG 47LB653V (Panel LC470DUH (FG)(P1)), LG 32LB653V (Panel LC320DUH( FG)(P1)), LG 42LB690V (Panel LC420DUH (PG)(F1)), LG 55LB630V (Panel LC550DUH).
The appearance of the power supply
Main features of the device LG 32LB650V:
Installed matrix (LED-panel) LC320DUH (FG) (P2).
To power the backlight LEDs, a converter is used, combined with a power supply unit, controlled by a PWM controller SSC1S311, A27RAE (sot23-6). As power elements of the LED driver, keys of the type STD11N65M5, STN4NF20L are used.
The necessary supply voltages for all nodes of the LG 32LB650V TV are generated by the LGP32-14PL1 power module or its analogs using NCP1251 microcircuits (PWM SOT23-6 5A2R ..), NR134S and KP8N65 type power switches.
MainBoard - the main board (motherboard) is an EAX65384004 module, using CPU chips: LG1311; DRAM: H5TQ4G63AFR-PBC; EEPROM: AT24C256C, EMMC: THGBMAG6A2JBAIR and others.
The tuner EBL61400501 TDJM-G101D provides reception of television programs and tuning to channels.
Additional technical information about the panel:
Brand: LG Display
Model: LC320DUH-FGP2
Type: a-Si TFT-LCD, Panel
Diagonal size: 31.5 inch
Resolution: 1920x1080, FHD
Display Mode: IPS, Normally Black, Transmissive
Active Area: 698.4x392.85 mm
Surface: Antiglare (Haze 1%), Hard coating (2H), Reflection 1.0%
Brightness: 300 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (8-bit)
Response Time: 8/10 (Tr / Td)
Frequency: 120Hz
Lamp Type: WLED Without Driver
Signal Interface: EPI, 100 pins
Voltage: 12.0V