Tuesday 11 February 2020

REPAIR / SERVICING TV LG 20LS5R

Technical description and composition of the LG 20LS5R TV, panel type and applicable modules. The composition of the modules.
LG
Model: 20LS5R
Chassis / Version: LP68A
Panel: LC201V02-SDA1
Lamp backlight: 6 Lamp CCFL
Inverter (backlight): integrated into PSU
PWM Inverter: OZ964GN
MOSFET Inverter: P2503BDG, P06P03LDG
Power Supply (PSU): EAY32636401 AIVP-0032
PWM Power: STRW6253
MainBoard: EAX31483004 (0)
IC MainBoard: CPU: LGE9655-LF, EEPROM: 24C64, SPI: MX25L4005
Tuner: TAFT-W005D
Specifications 20LS5R
LG 20LS5R
General recommendations for repairing TV LCD
Possible malfunctions
- LG 20LS5R does not turn on, the indicators on the front panel do not light up and do not blink. The TV does not respond to the control buttons and the remote control.
In such cases, the EAY32636401 power supply is usually faulty. It is necessary to measure its output voltages, and in case of their absence (full or partial), it is necessary to check the serviceability of the power switches of the converters and rectifier diodes for the presence of a possible short circuit.
In case of any breakdowns in the secondary circuits, the converter can operate in emergency short circuit mode, and during short circuit in the power elements of the primary circuit, the mains fuse or the current sensor at the source of the key more 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) STRW6253, 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.
The defect can be caused by problems in the nodes or elements of the backlight of the display, or in the power supply of the lamps or the inverter.After checking all the electrolytic capacitors of the filters that are involved in the power supply to the inverter, you must ring in its converter power keys for breakdown and secondary windings of transformers for an open.
If in diagnosing a malfunction, it is necessary to disable the inverter protection, there is a risk of failure of the power elements of the inverter, and special care is required during work, and after they are finished, it is necessary to restore the protection circuits for further safe operation of the TV by the owner in normal mode.
- The indicator on the front panel blinks, the TV does not turn on in operating mode, it does not respond to the remote control.
Repair or diagnostics of the EAX31483004 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). When repairing an MB board, you need to check its CPU components: LGE9655-LF, EEPROM: 24C64, SPI: MX25L4005. Defective items should be replaced. If chips with BGA soldering technology are used, a problem in its implementation is detected by the local heating of the chip.
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 power supply voltage of the TAFT-W005D tuner and update the software. The pulses from the I2C bus must be controlled with an oscilloscope.
Attention to users! Self-repair of the LG 20LS5R TV without the appropriate qualifications and the necessary experience can lead to its complete non-repairability!


FIRMWARE FOR  SPI FLASH ------->  LG 20LS5R LP68A, Main: EAX31483004 (0), Panel: LC201V02-SDA1.

 service manual and schematic diagram ---------------->  LG 20LS5R Chassis LP68A




 The appearance of the MainBoard EAX31483004 is shown in the figure below:
EAX31483004
The appearance of the power supply
Main features of the device LG 20LS5R:
Installed matrix (LCD panel) LC201V02-SDA1.
To power the backlight, a converter is used, combined with a power supply, controlled by the OZ964GN PWM controller. As power elements of the inverter, keys of the type P2503BDG, P06P03LDG are used.
The necessary supply voltages for all nodes of the LG 20LS5R TV are generated by the EAY32636401 power module, or its analogs using STRW6253 microcircuits.
MainBoard - the main board (motherboard) is an EAX31483004 module, using CPU chips: LGE9655-LF, EEPROM: 24C64, SPI: MX25L4005 and others.
The TAFT-W005D tuner provides TV reception and channel tuning.
Additional technical information about the panel:
Brand: LG.Philips LCD
Model: LC201V02-SDA1
Type: a-Si TFT-LCD, Panel
Diagonal size: 20.1 inch
Resolution: 640x480, VGA
Display Mode: IPS, Normally Black, Transmissive
Active Area: 408x306 mm
Surface: Antiglare, Hard coating (3H)
Brightness: 450 cd / m²
Contrast Ratio: 800: 1
Display Colors: 16.7M (8-bit), CIE1931 72%
Response Time: 12/13 (Tr / Td)
Frequency: 60Hz
Lamp Type: 6 pcs CCFL Without Driver
Signal Interface: CMOS (1 ch, 8-bit), 41 pins
Voltage: 12.0V