Sunday 23 February 2020

REPAIR / SERVICING TV LG 37LM620T

Technical description and composition of the LG 37LM620T TV, panel type and applicable modules. The composition of the modules.
LG LED
Model: 37LM620T
Chassis / Version: LD22E
Panel: LC370EUN (SE) (F2)
LED backlight: 6922L-0007A (cool); 6920L-0001C, 6916L1088A
T-CON: 6870C-0401B
LED driver (backlight): PPW-LE37SE-0, 6917L-0086A
Power Supply (PSU): EAX64405901 - EAY62569601, PSLC-L111A, 3PAGC10079A-R, LGP3237H-12P
MainBoard: EAX64307906 - EBR75226850
IC MainBoard: LCE2112 ic701-ic704 -H5TQ2G63DFR ic8100 - KLM2G1HE3F ic3000 - MICOM R5F100GEA ic7700 - TPS65178 ic5800 - STA3808WE ic100-24c16
Tuner: TDSN-G351D
Control: AKB73615303; IR: EBR74986703, LM35-55, MB32B00, 1BF-3010B
Specifications 37LM620T
LG 37LM620T
General repair guidelines for TV LCD LED
Malfunctions of the EAX64405901 - EAY62569601, PSLC-L111A, 3PAGC10079A-R, LGP3237H-12P power supply module can be expressed differently, for example, LG 37LM620T does not turn on at all and the control lights on its front panel do not light up and do not blink, there are no signs of working capacity. In the absence of swollen filter capacitors of the secondary rectifiers, the diagnostics of the power supply should be started by checking the fuse and, if it is broken, it is first necessary to check all the power semiconductor elements of the primary circuit - diodes and transistors for the possibility of an avalanche or thermal breakdown.
The reasons for the breakdown of the power switch in switching power supplies (IIPS) can be different, for example, a malfunction of semiconductor cells or electrolytic capacitors in the stabilization circuits of the primary circuit, as well as a failure in the operation of the PWM controller chip or broken resistors in its bundle.
If the LG 37LM620T does not have an image, but there is sound and the TV is controlled by the remote control, a malfunction in the backlight circuits of the LC370EUN (SE) panel (F2) is likely. LEDs or their 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 rectifier filter supplying the backlight assembly.

To check the health of the LEDs, as well as contact connections in the ruler circuit, it is necessary to disassemble the panel.

To open all transitions, several tens of volts or more are necessary, and it is best to use a current source for such purposes. A break in the line of LEDs connected in series cannot be detected with a multimeter or tester without disassembling the panel. In the open panel, it is necessary to check each LED. If your multimeter cannot open the LED transitions in forward bias, then see the presence of the PN transition of the protective zener diode by connecting the probes in the opposite direction. If the zener diode is broken or broken in short-circuit, then the LED is faulty and needs to be replaced.
Repair or diagnostics of the EAX64307906 - EBR75226850 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).

If it is not possible to replace the MB (SSB) card, you need to check the health of its elements - LCE2112 ic701-ic704 -H5TQ2G63DFR ic8100 - KLM2G1HE3F ic3000 - MICOM R5F100GEA ic7700 - TPS65178 ic5800 - STA3808WE ic100-24c16. Defective components should be replaced.
Before replacing the TDSN-G351D tuner, if there is no tuning for the channels, you must first check the software and the supply voltage at its terminals. It is also necessary to make sure that the tuner and processor can exchange data via the I2C bus
Attention! For users and owners of 37LM620T TVs who do not have the appropriate qualifications, knowledge and experience, we strongly recommend against self-repair attempts in order to avoid negative consequences that could lead to complete non-repairability of the device.


schematic diagram ------------->  LG CHASSIS LD22E; 32LM620S, 32LM6620T, 32LM620S-ZE, 32LM620T-ZE


 The appearance of the MainBoard EAX64307906 is shown in the figure below:
EAX64307906
EAX64307906 can be used in TVs:
LG 32LM640T ZA (Panel LC320EUA PE F2), LG 32LS570T (Panel LC320EUN (SE)(M2)), LG 47LM620S (Panel LC470EUE (SE)(F4)), LG 42LM670T (Panel LC420EUG(PE)(F2)), LG 42LM640T 42LM640S (Panel LC420EUG (PE)(F1)), LG 42LM620T (Panel LC420EUE (SE)(F1)), LG 47LM660T (Panel LC470EUG (PE)(F1)), LG 42LS570T (Panel T420HVN01.0), LG 42LS570S ZB (Panel LC420EUE (SE)(M1)), LG 42LM669T (Panel LC420EUG (PE)(F2)), LG 42LM669S (Panel LC420EUG (PE)(F1)), LG 37LM620T (Panel LC370EUN (SE)(F2)), LG 47LM669 (Panel LC470EUG (PE)(F2)), LG 32LS570S ZB (Panel LC320EUN (SE)(M2)), LG 47LM620T (Panel LC470EUE (SE)(F3)), LG 47LM761T ZA (Panel LC470EUH (PE)(F1), LG 32LM620S (Panel LC320EUN (SE)(F2) ), LG 47LM670T 47LM670T-ZA.BRUWLJU (Panel LC470EUG (PE)(F1)), LG 42LM660S 42LM660S-ZA.BRUWLJU (Panel LC420EUG (PE)(F1)), LG 42LM660T 42LM660T-ZA.BRUWLJU (Panel LC420EUG (PE)(F1) ), LG 32LM620T (Panel LC320EUN (SE)(F3)), LG 55LM620T 55LM620T-ZE (Panel LC550EUE (SE)(F1)).
The appearance of the power supply
Main features of the device LG 37LM620T:
Installed matrix (LED-panel) LC370EUN (SE) (F2).
The matrix control uses the Timing Controller (T-CON) 6870C-0401B.
The LED driver PPW-LE37SE-0 is used to power the backlight LEDs.
The formation of the necessary supply voltages for all nodes of the LG 37LM620T TV is carried out by the EAX64405901 power module, or its analogues.
MainBoard - the main board (motherboard) is an EAX64307906 module, using LCE2112 ic701-ic704-H5TQ2G63DFR ic8100 - KLM2G1HE3F ic3000 - MICOM R5F100GEA ic7700 - TPS65178 ic5800 - STA3808W16- ic100 chips.
The TDSN-G351D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC370EUN-SEF2
Type: a-Si TFT-LCD, Panel
Diagonal size: 36.5 inch
Resolution: 1920x1080, FHD
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 808.128x454.572 mm
Display Colors: 16.7M (8-bit)
Response Time: 6 (G to G)
Lamp Type: WLED