Tuesday 18 February 2020

REPAIR / SERVICING TV LG 32LG4000

Technical description and composition of the LG 32LG4000 TV, panel type and applicable modules. The composition of the modules.
LG
Model: 32LG4000 ZA
Chassis / Version: LD86A
Panel: LC320WXN (SB) (A3)
T-CON: LC320WXN-S6A-1 P / N6870C-0238A
Inverter (backlight): LC320WXN P / N 6692L-0528A
Power Supply (PSU): EAY4050440 LGP32-08H
PWM Power: SG6961SZ (PFC), NCP1396ADR2G, NCP1207ADR2G
MainBoard: EAX50912202 (0) (stiker: AGF66430007)
IC MainBoard: NTP-3000A
Tuner: TDFV-G135D
Control: EAY4050440
Specifications 52LG5030
LG 32LG4000
General recommendations for repairing TV LCD
Any repair usually begins with an external inspection. Visible damage to elements can sometimes indicate the direction of the search for a defect even before the necessary measurements are taken. Experienced repairmen are well aware of how ring cracks in soldered terminals look, swollen capacitors, and other causes of problems in electronic devices.
If the 32LG4000-ZA TV does not turn on, does not make any sounds when it is turned on, and also no indicators on the front panel light or blink - there is a high probability of a malfunction in the power supply module. In some cases, there may be a malfunction only in standby power. 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 elements or electrolytic capacitors in the stabilization circuits of the primary circuit, as well as a failure in the operation of the PWM controller SG6961SZ, NCP1396ADR2G, NCP1207ADR2G or broken resistors in its bundle .
If the LG 32LG4000-ZA does not have an image, but there is sound and the TV is controlled from the remote control, a malfunction in the display backlight nodes is likely. The lamps or the power converter - inverter 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 inverter, and check the LCD lamps by connecting external and obviously serviceable for diagnosis to the connectors. All necessary precautions must be observed when disabling the inverter protection during diagnostics and not leaving it disconnected after the repair is completed.
If the motherboard EAX50912202 (0) is faulty (sticer: AGF66430007), first of all it is necessary to check all the linear stabilizers and power converters of its chips, and also, if necessary, update the software (software). Sometimes you can check the health of MB only by replacement. Sophisticated MB board repair (SSB) is in some cases possible and practiced by repairmen. To do this, check and, if necessary, replace the NTP-3000A elements. BGA chip malfunctions are usually easy to detect by warming up.
Before replacing the TDFV-G135D tuner, if there is no tuning for the channels, you must first check the software and the supply voltage at its terminals.
Attention to the owners! Attempts at self-repair of the LG 32LG4000-ZA TV are not recommended by the manufacturer and can lead to serious negative consequences!


SCHEMATIC MANUAL ------------------->  LG CHASSIS: LD86A MODEL: 32LG4000, 32LG4000-ZA.



 The appearance of the MainBoard EAX50912202 is shown in the figure below:
EAX50912202
EAX50912202 can be used in TVs:
LG 26LG4000 (Panel T260XW02 V.R), LG 32LG4000 ZA (Panel LC320WXN (SB)(A3)).
PSU Advanced
The EAY4050440 power module is made using a Power Factor Correction (PFC) scheme to eliminate multiple AC harmonics introduced into the power supply by the device. The PFC assembly is a Step-Up Converter based on the SG6961SZ PWM controller, which evenly distributes high-frequency impulses of the charging current of the electrolytic capacitor of the rectifier filter of the mains voltage over a period of 50 Hz. The current of its charge in this case will already be determined not by its reactance (usually 10-30 ohms for the network frequency), but by the elements of the converter. As a result, a change in the amplitude of the pulses (envelope) of the consumed current of the converter will repeat the shape and phase of the input sinusoidal voltage. The availability of an increased voltage (about + 380V) in the operating mode on the capacitor of the line filter indicates the serviceability of the PFC node.
The appearance of the power supply
Main features of the device LG 32LG4000:
Installed matrix (LCD panel) LC320WXN (SB) (A3).
The matrix control uses the Timing Controller (T-CON) LC320WXN-S6A-1.
To power the backlight used inverter LC320WXN.
The necessary supply voltages for all nodes of the LG 32LG4000 TV are generated by the EAY4050440 power module, or its analogs using SG6961SZ (PFC), NCP1396ADR2G, NCP1207ADR2G microcircuits.
MainBoard - the main board (motherboard) is an EAX50912202 module, using NTP-3000A chips and others.
The TDFV-G135D tuner provides television reception and channel tuning.
Additional technical information about the panel:
Brand: LG Display
Model: LC320WXN-SBA3
Type: a-Si TFT-LCD, Panel
Diagonal size: 31.5 inch
Resolution: 1366x768, WXGA
Display Mode: S-IPS, Normally Black, Transmissive
Active Area: 697.685x392.256 mm
Surface: Antiglare (Haze 10%), Hard coating (3H)
Brightness: 500 cd / m²
Contrast Ratio: 1200: 1
Display Colors: 16.7M (8-bit)
Response Time: 8 (G to G)
Frequency: 60Hz
Lamp Type: 12 pcs EEFL Embedded (Inverter)
Signal Interface: LVDS (1 ch, 8-bit), 30 pins
Voltage: 12.0V