Sunday 23 February 2020

REPAIR / SERVICING TV LG 37LC2R

Technical description and composition of the LG 37LC2R TV, panel type and applicable modules. The composition of the modules.
LG
Model: 37LC2R
Chassis / Version: PP62ABC / LP62ABC
Panel: LC370WX1 (SL) (13)
T-CON: 6870C-0060H
Inverter (backlight): 6632L-0197C LC370WX1 (MASTER) YPNL-T010C (S) REV06, 6632L-0198C LC370WX1 (SLAVE) YPNL-T010D (S) REV06
Power Supply (PSU): 68709D0006B
PWM Power: F9223L (PWM), FA5501A (PFC), STR-W6251
MOSFET Power: W20NM60
MainBoard: 68709M9004F 37LC2R-ZH.ALRLLBN
IC MainBoard: FLI8662, SIL9021CTU, 24LC256, NTP2000, MSP4410K, CXA2069Q, HY5DU281622ETP-5
Tuner: TAUM-W502P / TAFM-W502P
Specifications 37LC2R
LG 37LC2R
General recommendations for repairing TV LCD
Possible malfunctions
- The LG 37LC2R TV does not turn on and does not show any signs of operability at all. There is no reaction to the remote control and control buttons from the front panel.
Most often, with such manifestations, the main power module 68709D0006B is found to be faulty. It is necessary to measure its output supply voltage, and in case of their absence, check the serviceability of the power switches (W20NM60) of the converters and rectifier diodes for the probability of breakdown in PN semiconductor junctions.
In case of breakdowns of semiconductors in secondary circuits, the converter can usually work abnormally in the short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse 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 circuits (OOS) of stabilization. PWM controllers (PWM) F9223L (PWM), FA5501A (PFC), STR-W6251, 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. Or the image may appear for a second when turned on and immediately disappears.
These manifestations can be triggered by the power module, or by inverter defects, as well as by the distortion of the currents in the lamps due to their uneven wear. If all the electrolytic capacitors of the filter according to the inverter power supply are serviceable, you should make sure that the lamps are in good working condition, then you need to check the converter keys and the secondary windings of the transformers.
Sometimes, for diagnostic purposes, it is necessary to disable the inverter protection. In such cases, special care must be taken during work, and the protection circuits should be restored immediately after the repair is completed.
- The TV does not turn on, does not respond to the remote control. The indicator blinks or signals standby mode.
Repair or diagnostics of the 68709M9004F 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). Sometimes it is necessary to check or replace (if necessary) the elements of the MainBoard board - SIL9021CTU, NTP2000, MSP4410K, CXA2069Q. In cases where the BGA processor is used, its malfunction is usually detected by the local heating method.
If a TAUM-W502P / TAFM-W502P tuner is suspected of malfunction, first of all, it is necessary to verify the correctness of the software, as well as the presence of the necessary voltage levels and the data exchange pulses with the processor via the I2C bus at the corresponding tuner pins.
Attention TV owners! Self-repair attempts by LG 37LC2R are not recommended by the manufacturer and can lead to serious negative consequences!


schematic diagram -------------> LG CHASSIS: LP62C MODEL: 37LC2R, 42LC2R.



 The appearance of MainBoard 68709M9004F is shown in the figure below:
68709M9004F
The appearance of the power supply
Main features of the device LG 37LC2R:
The matrix (LCD panel) LC370WX1 (SL) (13) is installed.
The matrix control uses the Timing Controller (T-CON) 6870C-0060H.
An inverter 6632L-0197C is used to power the backlight.
The necessary supply voltages for all nodes of the LG 37LC2R TV are generated by the power supply module 68709D0006B, or its analogs using microcircuits F9223L (PWM), FA5501A (PFC), STR-W6251 and power switches of the type W20NM60.
MainBoard - the main board (motherboard) is a module 68709M9004F, using chips FLI8662, SIL9021CTU, 24LC256, NTP2000, MSP4410K, CXA2069Q, HY5DU281622ETP-5 and others.
The TAUM-W502P / TAFM-W502P tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: LG.Philips LCD
Model: LC370WX1-SL13
Type: a-Si TFT-LCD, Panel
Diagonal size: 37 inch
Resolution: 1366x768, WXGA
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 819.6x460.8 mm
Surface: Antiglare, Hard coating (3H)
Brightness: 500 cd / m²
Contrast Ratio: 800: 1
Display Colors: 16.7M (8-bit)
Response Time: 8/10 (Tr / Td); 9 (G to G)
Frequency: 60Hz
Lamp Type: 20 pcs EEFL Embedded (Inverter)
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 12.0V