LED TV SERVICE MANUAL

SAFETY PRECAUTIONS

IMPORTANT SAFETY NOTICE

Many electrical and mechanical parts in this chassis have special safety-related characteristics. These parts are identified by [safety-icon] in the Exploded View. It is essential that these special safety parts should be replaced with the same components as recommended in this manual to prevent Shock, Fire, or other Hazards. Do not modify the original design without permission of manufacturer.

General Guidance

• An isolation Transformer should always be used during the servicing of a receiver whose chassis is not isolated from the AC power line. Use a transformer of adequate power rating as this protects the technician from accidents resulting in personal injury from electrical shocks. It will also protect the receiver and its components from being damaged by accidental shorts of the circuitry that may be inadvertently introduced during the service operation.
• If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it with the specified one.
• When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1 W), keep the resistor 10 mm away from PCB.
• Keep wires away from high voltage or high temperature parts.
• Before returning the receiver to the customer, always perform an AC leakage current check on the exposed metallic parts of the cabinet, such as antennas, terminals, etc., to be sure the set is safe to operate without damage of electrical shock.

Leakage Current Cold Check (Antenna Cold Check)

With the instrument AC plug removed from AC source, connect an electrical jumper across the two AC plug prongs. Place the AC switch in the on position, connect one lead of ohm-meter to the AC plug prongs tied together and touch other ohm-meter lead in turn to each exposed metallic parts such as antenna terminals, phone jacks, etc. If the exposed metallic part has a return path to the chassis, the measured resistance should be between 1 MΩ and 5.2 MΩ. When the exposed metal has no return path to the chassis the reading must be infinite. An other abnormality exists that must be corrected before the receiver is returned to the customer.

Leakage Current Hot Check

Plug the AC cord directly into the AC outlet. Do not use a line Isolation Transformer during this check. Connect a 1.5 KΩ / 10 watt resistor in parallel with a 0.15 μF capacitor between a known good earth ground (Water Pipe, Conduit, etc.) and the exposed metallic parts. Measure the AC voltage across the resistor using AC voltmeter with 1000 ohms/volt or more sensitivity. Reverse plug the AC cord into the AC outlet and repeat AC voltage measurements for each exposed metallic part. Any voltage measured must not exceed 0.75 volt RMS which corresponds to 0.5 mA. In case any measurement is out of the limits specified, there is possibility of shock hazard and the set must be checked and repaired before it is returned to the customer.

[Diagram Description: Circuit diagram for Leakage Current Hot Check showing AC outlet, parallel connection of 1.5KΩ resistor and 0.15μF capacitor, connected between earth ground and exposed metallic parts, with an AC voltmeter measuring voltage across the resistor.]

SERVICING PRECAUTIONS

CAUTION: Before servicing receivers covered by this service manual and its supplements and addenda, read and follow the SAFETY PRECAUTIONS on page 3 of this publication. NOTE: If unforeseen circumstances create conflict between the following servicing precautions and any of the safety precautions on page 3 of this publication, always follow the safety precautions. Remember: Safety First.

General Servicing Precautions

• Always unplug the receiver AC power cord from the AC power source before: removing or reinstalling any component, circuit board module or any other receiver assembly; disconnecting or reconnecting any receiver electrical plug or other electrical connection; connecting a test substitute in parallel with an electrolytic capacitor in the receiver. CAUTION: A wrong part substitution or incorrect polarity installation of electrolytic capacitors may result in an explosion hazard.
• Test high voltage only by measuring it with an appropriate high voltage meter or other voltage measuring device (DVM, FETVOM, etc) equipped with a suitable high voltage probe. Do not test high voltage by "drawing an arc".
• Do not spray chemicals on or near this receiver or any of its assemblies.
• Unless specified otherwise in this service manual, clean electrical contacts only by applying the following mixture to the contacts with a pipe cleaner, cotton-tipped stick or comparable non-abrasive applicator: 10 % (by volume) Acetone and 90 % (by volume) isopropyl alcohol (90 % - 99 % strength). CAUTION: This is a flammable mixture. Unless specified otherwise in this service manual, lubrication of contacts is not required.
• Do not defeat any plug/socket B+ voltage interlocks with which receivers covered by this service manual might be equipped.
• Do not apply AC power to this instrument and/or any of its electrical assemblies unless all solid-state device heat sinks are correctly installed.
• Always connect the test receiver ground lead to the receiver chassis ground before connecting the test receiver positive lead. Always remove the test receiver ground lead last.
• Use with this receiver only the test fixtures specified in this service manual. CAUTION: Do not connect the test fixture ground strap to any heat sink in this receiver.

Electrostatically Sensitive (ES) Devices

Some semiconductor (solid-state) devices can be damaged easily by static electricity. Such components commonly are called Electrostatically Sensitive (ES) Devices. Examples of typical ES devices are integrated circuits and some field-effect transistors and semiconductor "chip" components. The following techniques should be used to help reduce the incidence of component damage caused by static electricity.

• Immediately before handling any semiconductor component or semiconductor-equipped assembly, drain off any electrostatic charge on your body by touching a known earth ground. Alternatively, obtain and wear a commercially available discharging wrist strap device, which should be removed to prevent potential shock reasons prior to applying power to the unit under test.
• After removing an electrical assembly equipped with ES devices, place the assembly on a conductive surface such as aluminum foil, to prevent electrostatic charge buildup or exposure of the assembly.
• Use only a grounded-tip soldering iron to solder or unsolder ES devices.
• Use only an anti-static type solder removal device. Some solder removal devices not classified as "anti-static" can generate electrical charges sufficient to damage ES devices.
• Do not use freon-propelled chemicals. These can generate electrical charges sufficient to damage ES devices.
• Do not remove a replacement ES device from its protective package until immediately before you are ready to install it. (Most replacement ES devices are packaged with leads electrically shorted together by conductive foam, aluminum foil or comparable conductive material).
• Immediately before removing the protective material from the leads of a replacement ES device, touch the protective material to the chassis or circuit assembly into which the device will be installed. CAUTION: Be sure no power is applied to the chassis or circuit, and observe all other safety precautions.
• Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise harmless motion such as the brushing together of your clothes fabric or the lifting of your foot from a carpeted floor can generate static electricity sufficient to damage an ES device.)

General Soldering Guidelines

• Use a grounded-tip, low-wattage soldering iron and appropriate tip size and shape that will maintain tip temperature within the range of 500 °F to 600 °F (approx. 260 °C to 315 °C).
• Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.
• Keep the soldering iron tip clean and well tinned.
• Thoroughly clean the surfaces to be soldered. Use a small wire-bristle (0.5 inch, or 1.25 cm) brush with a metal handle. Do not use freon-propelled spray-on cleaners.
• Use the following unsoldering technique: a. Allow the soldering iron tip to reach normal temperature (500 °F to 600 °F). b. Heat the component lead until the solder melts. c. Quickly draw the melted solder with an anti-static, suction-type solder removal device or with solder braid. CAUTION: Work quickly to avoid overheating the circuit board printed foil.
• Use the following soldering technique: a. Allow the soldering iron tip to reach a normal temperature (500 °F to 600 °F). b. First, hold the soldering iron tip and solder the strand against the component lead until the solder melts. c. Quickly move the soldering iron tip to the junction of the component lead and the printed circuit foil, and hold it there only until the solder flows onto and around both the component lead and the foil. CAUTION: Work quickly to avoid overheating the circuit board printed foil. d. Closely inspect the solder area and remove any excess or splashed solder with a small wire-bristle brush.

IC Remove/Replacement

Some chassis circuit boards have slotted holes (oblong) through which the IC leads are inserted and then bent flat against the circuit foil. When holes are the slotted type, the following technique should be used to remove and replace the IC. When working with boards using the familiar round hole, use the standard technique as outlined in paragraphs 5 and 6 above.

• Removal: Desolder and straighten each IC lead in one operation by gently prying up on the lead with the soldering iron tip as the solder melts. Draw away the melted solder with an anti-static suction-type solder removal device (or with solder braid) before removing the IC.
• Replacement: Carefully insert the replacement IC in the circuit board. Carefully bend each IC lead against the circuit foil pad and solder it. Clean the soldered areas with a small wire-bristle brush. (It is not necessary to reapply acrylic coating to the areas).

"Small-Signal" Discrete Transistor Removal/Replacement

• Remove the defective transistor by clipping its leads as close as possible to the component body.
• Bend into a "U" shape the end of each of three leads remaining on the circuit board.
• Bend into a "U" shape the replacement transistor leads.
• Connect the replacement transistor leads to the corresponding leads extending from the circuit board and crimp the "U" with long nose pliers to insure metal to metal contact then solder each connection.

Power Output, Transistor Device Removal/Replacement

• Heat and remove all solder from around the transistor leads.
• Remove the heat sink mounting screw (if so equipped).
• Carefully remove the transistor from the heat sink of the circuit board.
• Insert new transistor in the circuit board.
• Solder each transistor lead, and clip off excess lead.
• Replace heat sink.

Diode Removal/Replacement

• Remove defective diode by clipping its leads as close as possible to diode body.
• Bend the two remaining leads perpendicular to the circuit board.
• Observing diode polarity, wrap each lead of the new diode around the corresponding lead on the circuit board.
• Securely crimp each connection and solder it.
• Inspect (on the circuit board copper side) the solder joints of the two "original" leads. If they are not shiny, reheat them and if necessary, apply additional solder.

Circuit Board Foil Repair

Excessive heat applied to the copper foil of any printed circuit board will weaken the adhesive that bonds the foil to the circuit board causing the foil to separate from or "lift-off" the board. The following guidelines and procedures should be followed whenever this condition is encountered.

At IC Connections

To repair a defective copper pattern at IC connections use the following procedure to install a jumper wire on the copper pattern side of the circuit board. (Use this technique only on IC connections).

• Carefully remove the damaged copper pattern with a sharp knife. (Remove only as much copper as absolutely necessary).
• Carefully scratch away the solder resist and acrylic coating (if used) from the end of the remaining copper pattern.
• Bend a small "U" in one end of a small gauge jumper wire and carefully crimp it around the IC pin. Solder the IC connection.
• Route the jumper wire along the path of the out-away copper pattern and let it overlap the previously scraped end of the good copper pattern. Solder the overlapped area and clip off any excess jumper wire.

At Other Connections

Use the following technique to repair the defective copper pattern at connections other than IC Pins. This technique involves the installation of a jumper wire on the component side of the circuit board.

• Remove the defective copper pattern with a sharp knife. Remove at least 1/4 inch of copper, to ensure that a hazardous condition will not exist if the jumper wire opens.
• Trace along the copper pattern from both sides of the pattern break and locate the nearest component that is directly connected to the affected copper pattern.
• Connect insulated 20-gauge jumper wire from the lead of the nearest component on one side of the pattern break to the lead of the nearest component on the other side. Carefully crimp and solder the connections. CAUTION: Be sure the insulated jumper wire is dressed so that it does not touch components or sharp edges.

Fuse and Conventional Resistor Removal/Replacement

• Clip each fuse or resistor lead at top of the circuit board hollow stake.
• Securely crimp the leads of replacement component around notch at stake top.
• Solder the connections. CAUTION: Maintain original spacing between the replaced component and adjacent components and the circuit board to prevent excessive component temperatures.

SPECIFICATION

NOTE: Specifications and others are subject to change without notice for improvement.

1. Application range: This specification is applied to the LED TV used UA71J chassis.

2. Test condition: Each part is tested as below without special appointment.

• (1) Temperature: 25 °C ± 5 °C, CST: 40 °C ± 2 °C
• (2) Relative Humidity: 65 % ± 10 %
• (3) Power Voltage: Standard input voltage (AC 100-240 V~, 50/60 Hz) * Standard Voltage of each products is marked by models.
• (4) Specification and performance of each parts are followed each drawing and specification by part number in accordance with BOM.
• (5) The receiver must be operated for about 5 minutes prior to the adjustment.

3. Test method:

• (1) Performance: LGE TV test method followed
• (2) Demanded other specification - Safety: CE, IEC specification - EMC: CE, IEC

4. General Specification

5. External Input Support Format

5.1. Component (Y, CB/PB, CR/PR)

5.2. HDMI Input (PC/DTV)

HDMI-PC

DTV

Spec. out but display

SOFTWARE UPDATE

1. USB Update:

1. Insert the USB memory stick to the USB port.
2. The system automatically detects the SW Version and displays a message.
3. Click [YES] to initiate the download and installation of the update.
4. After the update is finished, a pop-up message appears.
5. Click [Yes] to restart the TV (DC OFF -> ON).
6. After the TV turns on, check the updated SW Version and Tool Option.

2. NSU (Network Software Update):

(This function requires an internet connection)

1. Navigate to Menu -> All Settings -> General -> About This TV.
2. Click [CHECK FOR UPDATES] to check for the newest version.
3. Click [DOWNLOAD AND INSTALL] to download and install the update.
4. The TV will be updating.
5. After the update is finished, a pop-up message appears.
6. Turn OFF the TV and then turn it ON. Check the updated SW Version and Tool Option.

BLOCK DIAGRAM

[Diagram Description: The block diagram illustrates the internal architecture of the LG LED TV. Key components include:

• Inputs: Air/RF Cable, TUNER (C/A), USB1 (2.0), USB2 (2.0), HDMI1-4 (supporting 2.0, ARC for HDMI2), RS232C/HP, CVBS/COMP, OPTIC (SPDIF Out), LAN (ETHERNET).
• Tuner & Demodulator: Receives RF signals, processes IF+, IF-, SIF, CVBS, P_TS.
• Memory: DDR3 (2133 512MB, 2133 256MB), EEPROM (NVRAM 256Kb), eMMC (4GB).
• Main Processor & System: Includes a Main Micom, Sub Micom (for Key/IR sensing), PMIC (Power Management IC), GAMMA IC, Sub PMIC.
• Audio: Main Audio AMP.
• Connectivity: WIFI/BT Combo, IR/KEY, LOGO LIGHT (Ready).
• Internal Clocks: X_TAL (24MHz, 32.768KHz).
• Interconnections: Various I2C buses (I2C 0, 1, 4, 6), OCP, USB_WIFI, PHY signals (RX0N for USB/WIFI), SPDIF OUT, ETHERNET.
• Power Supply Unit (PSU): Provides power to the various boards.
• Panel: The display panel itself, connected via FFC cable.
• Other Boards/Modules: SUB ASSY, WIFI bracket.

The diagram shows signal paths from inputs through processing units to outputs, highlighting the integration of various components for TV functionality.]

EXPLODED VIEW

[Diagram Description: The exploded view illustrates the physical layout of the TV's internal components, showing how they are assembled. It depicts the back cover, various internal boards (like the main board and power board), the display panel, speakers, and other modules. Specific screw types and quantities are indicated for disassembly steps.]

DISASSEMBLY

Note: The disassembly screw torque is 5 ~ 7Kgf.cm.

For 43" Model:

1. Disassemble the screws in the Back cover.
2. Disassemble the power board, main board, key board, and WIFI bracket.

Screw Specifications for 43" Back Cover: AM3*6 BLACK (12 pcs), WM 6*20 (HARDEN) (4 pcs), B3 4*10 BLACK (1 pc), PM 4*14 BLACK (4 pcs).

Screw Specifications for 43" Boards/Bracket: WM 3 X 10 (9 pcs), AM 3*6 BLACK (2 pcs).

For 49" & 55" & 65" Models:

1. Disassemble the screws in the Back cover.
2. Disassemble the power board, main board, key board, and WIFI bracket.

Screw Specifications for 49"/55"/65" Back Cover: AM3*6 BLACK (14 pcs for 49", 15 pcs for 55", 18 pcs for 65"), WM 6*20 (HARDEN) (4 pcs), B3 4*10 BLACK (1 pc), PM 4*14 BLACK (4 pcs).

Screw Specifications for 49"/55"/65" Boards/Bracket: WM 3 X 10 (9 pcs), AM 3*6 BLACK (2 pcs).

LCD TV Repair Guide & TROUBLE SHOOTING GUIDE

This section provides detailed guidance for diagnosing and resolving common TV issues.

Contents of Standard Repair Process

Standard Repair Process Details

A. Video error

1. No video/Normal audio:
   • Check Back Light On with naked eye.
   • If backlight is ON: Check Power Board 13V output. If normal, replace T-con/Main Board or module. If not normal, repair Power Board or parts.
   • If backlight is OFF: Check Power Board 13V output. If normal, replace Inverter or module. If not normal, repair Power Board or parts.
   • Precaution: Always check & record S/W Version and White Balance value before replacing the Main Board. Re-enter White Balance value after replacement.
2. No video/No audio:
   • Check voltage of Power Board (e.g., 13V).
   • If voltages are normal, check and replace MAIN B/D.
   • If voltages are not normal, replace Power Board and repair parts.
3. Picture broken/ Freezing:
   • Check RF Signal level using a Digital signal level meter or Diagnostics menu on OSD (Signal strength and quality should be normal, typically over 50%).
   • If signal is not normal: Check RF Cable Connection (reconnect or install booster). Contact signal distributor or broadcaster if issues persist.
   • If signal is normal: Check if other equipment has the same problem. Check S/W Version; if outdated, perform S/W Upgrade. Check Tuner soldering. If issues persist, replace Main B/D.
4. Color error:
   • Check color by input type (External Input: COMPONENT, AV, HDMI).
   • Check Test pattern.
   • If color error persists across inputs: Check and replace Link Cable (V by one) and contact condition.
   • If color error is specific to an input: Check external device and cable for that input.
   • If color error persists after checking cables and external devices: Replace Main/T-con B/D.
5. Vertical/Horizontal bar, residual image, light spot, external device color error:
   • Check screen condition by input type (External Input, Component, HDMI).
   • Check Test pattern.
   • If screen is not normal on test pattern: Replace module.
   • If screen is normal on test pattern but not on inputs: Check external device connection condition and Link Cable. If external device/cable is faulty, request repair.
   • If screen is not normal after checking external devices and cables: Replace Main/T-con B/D.
   • For external device color error: Check S/W Version; if outdated, perform S/W Upgrade. Connect other external devices to test. If issues persist, replace Main/T-con B/D.

B. Power error

1. No power:
   • Check Logo LED status (Stand-By: Red, Operating: Green/White).
   • Check Power cord insertion.
   • Attempt DC Power on by pressing the Power Key. If normal operation, the issue might be with the remote control.
   • Measure voltages of each output of the Power B/D (e.g., ST-BY 3.5V, 13V).
   • If voltages are normal, replace Main B/D.
   • If voltages are not normal, replace Power B/D.
2. Off when on, off while viewing, power auto on/off:
   • Check outlet and A/C cord.
   • Check for all 3-phase power outputs.
   • Check Power Off Mode status via the adjustment menu (e.g., "POWEROFF_REMOTEKEY", "POWEROFF_AUTOOFF", "POWEROFF_CPUABNORMAL").
   • If CPU Abnormal or other abnormal status is indicated, replace Main B/D.
   • If Power Off mode is not displayed or indicates normal status but the TV turns off, check Power B/D voltages. If voltages are abnormal, replace Power B/D. If voltages are normal, replace Main B/D.

C. Audio error

1. No audio/Normal video:
   • Check user menu settings: Settings -> Sound -> Sound Out -> TV Speaker. Ensure it's not set to external or off.
   • Check audio B+ voltage (e.g., 13V) from the Power Board. If normal, replace MAIN Board. If not normal, replace Power Board.
   • Check Speaker connection and condition. If disconnected, reconnect. If faulty, replace Speaker.
2. Wrecked audio/discontinuation/noise:
   • Check input signal (RF, External Input). If signal is normal, check and replace speaker and connector. If still problematic, replace Main B/D.
   • If signal is not received: Request repair to external cable/ANT provider or check/fix external device.
   • Check audio B+ Voltage (13V) from Power Board. If normal, replace Main B/D. If not normal, replace Power B/D.
   • For External Input specific issues: Connect and check other external devices. If other devices work, check/fix the faulty external device.

D. Function error

1. Remote control & Local switch checking:
   • Check R/C itself: Operate in a dark room, check battery. If it works, interference from light is the cause. If not, replace R/C.
   • Check IR cable condition between IR module and Main board.
   • Check standby 3.5V on the Main B/D (e.g., terminal 22 pin).
   • Check IR Output signal. If IR output signal is abnormal, check 3.5V on Power B/D and replace Power B/D or Main B/D. If IR output signal is normal, repair/replace IR B/D.
2. MR15 (Magic Remote) operating checking:
   • Check IN-START menu for RF Receiver version. If "00.00", check/repair RF Assy connection or replace Battery of MR15.
   • If MR15 operates normally after battery replacement or RF Assy check, check firmware download option in IN-START menu.
   • If MR15 still does not operate normally, replace MR15.
3. Wifi operating error:
   • Check IN-START menu for Wi-Fi Mac value. If "NG", check Wifi cable connection and Wifi wafer 1pin voltage.
   • If voltage is normal but Mac value is "NG", change the Wifi Assy.
   • If voltage is abnormal, replace Main B/D.
4. Camera operating error:
   • Check IN-START menu for Camera Ver. If "NULL", reconnect the Camera module.
   • If Camera still does not operate normally, change the Camera module.
   • If issues persist after module replacement, replace Main B/D.
5. External device recognition error:
   • Check input signal and external device/cable.
   • Consult technical information for S/W Version fixes.
   • For External Input and Component recognition errors, or HDMI/DVI, Optical recognition errors, replace Main B/D.

E. Noise

1. Circuit noise, mechanical noise:
   • Identify noise type (circuit or mechanical).
   • Check location of noise.
   • For severe noise, replace the module. If there is specific fix information, upgrade S/W.
   • For "Tak Tak" noise from the cabinet, refer to KMS fix information.
   • For mechanical noise, follow the described process.

F. Exterior error

1. Exterior defect:
   • For module damage, replace module.
   • For cabinet damage, replace cabinet.
   • For remote control damage, replace remote control.
   • For stand dent, replace stand.

Contents of Standard Repair Process Detail Technical Manual

Detailed Repair Process Examples:

A. Video error_No video/Normal audio:

• Check LCD back light with naked eye: After turning on the power and disassembling the case, check if light is visible from the panel locations.
• Check White Balance value: Enter adjustment mode using the ADJ button on the remote. Navigate to White Balance settings (item 6.1.3). Record current R, G, B (GAIN, Cut-off) values. After replacing the Main Board, re-enter these values.
• TUNER input signal strength checking method: Access All Settings -> Channels -> Channel Tuning -> Manual Tuning. Use an attenuator (-10dB, -15dB, -20dB) if the signal is too strong.
• Version checking method: Press the IN-START button on the adjustment remote control to access adjustment items and check the version.
• TUNER checking part: Check signal strength or screen condition with an external device connected. Measure voltages from the power supply. If issues persist, replace the MAIN BOARD. For UHD live TV, connect signal to the left side jack (Korea model specific).
• Connection diagram: Check screen condition by signal for external inputs.
• Check Link Cable (EPI/Vby1) reconnection condition: Check the contact condition of the Link Cable, ensuring it is free from dust and properly inserted.
• Adjustment Test pattern - ADJ Key: Use the ADJ Key to view 6 types of patterns. Check for defective pixels, residual images, module errors (ADD-BAR, SCAN BAR), and classify video errors between MODULE or Main-B/D.

Appendix:

• Exchange Main Board (1): Covers issues like solder defects, CNT broken, abnormal power section, short/crack solder.
• Defected Type caused by T-Con/ Inverter/ Module: Lists common defects related to these components.
• Exchange Main Board (2): Covers abnormal power section, solder defects, fuse open, abnormal display, gradation, noise.
• Exchange Power Board (PSU): Addresses issues like no light, dim light, no picture/sound ok.
• Exchange the Module (1): Covers press damage, crosstalk, and un-repairable cases requiring module exchange.
• Exchange the Module (2): Covers vertical block, source TAB IC defect, horizontal block, gate TAB IC defect, and un-repairable cases.

B. Power error_No power:

• Check front Power Indicator: Observe the LED status.
• Check power input voltage and ST-BY 3.5V: Measure the DC 13V at the 14PIN connector on the Power Board. Also check the 13V input voltage supplied from the Power Board to the Main Board (14PIN).

B. Power error_Off when on, off while viewing:

• POWER OFF MODE checking method: Entry method: Press IN-START button on adjustment remote control, then check adjustment item 3.

C. Audio error_No audio/Normal video:

• Checking method in menu when there is no audio: Press Setting button -> Sound function -> Sound Out -> TV Speaker.
• Voltage and speaker checking method when there is no audio: Check the contact condition of the 13V connector of the Main Board. Measure the 13V input voltage from the Power Board. Connect a tester RX1 to the speaker terminal; if a "Chik Chik" sound is heard when touching GND and output terminal, the speaker is normal.

D. Function error:

• Remote control operation checking method: Check IR cable condition between IR & Main board. Check standby 3.5V on terminal 22 pin. Check IR Output signal. If IR LED light moves slowly when power is ON, it's defective.
• Wifi Only Front/Rear: Check Wifi cable condition between Wifi Only Assy & Main board. Check the 3.5V on terminal 1.