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LG WT4901C Series, Service Manual

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LG WT4901C Series Service Manual Download Page 20

4-1. DISASSEMBLY INSTRUCTION

20

▶ 

 Be sure to unplug the power to repair and replace 

electric parts.

ESD (ElectroStatic DIscharge) WARNING

Be sure to follow proper ESD and grounding 

precautions for diagnosis and repair. If this is not 

possible, touch the ground wire on a regular basis to 

remove any static charge built up on your person. 

1)  Remove front panel and main PCB 

assembly

  

①  

Remove 5 panel screws attaching the panel on the 

back. 

② 

Remove the rear panel.

③ 

Pull the front panel forward.

④ 

Disassemble the protective cover.

⑤ 

Disconnect the leads from the controller.

⑥ 

Remove 8 screws on the PCB assembly.

⑦ 

Remove the PCB assembly.

rear Panel

Main PCB

Protect Cover

display PCB

4. SERVICE INFORMATION

Summary of Contents for WT4901C Series

Page 1: ...WASHING MACHINE SERVICE MANUAL READ THIS MANUAL CAREFULLY TO DIAGNOSE PROBLEMS CORRECTLY BEFORE SERVICING THE UNIT CAUTION MODEL WT4901C WT4970C ...

Page 2: ...nce is energized Pump bracket rotor and heater Disconnect this appliance from the power supply before servicing Turning the controls to the off position does not disconnect this appliance from the power supply Failure to do this can result in shock Reconnect all grounded devices after servicing Failure to do this can result in shock CONTENTS 1 Specifications 3 2 Installation Instructions 2 1 How t...

Page 3: ...0V 60Hz Spin Speed 1100 50 rpm Weight 145 5 lbs 66kg Cycles Cotton Normal Perm Press Heavy Duty Bulky Bedding Bright WhitesTM Tub Clean Speed Wash Delicates Time Delay 1 19 Hr Lid Interlock Switch Magnet Sensor Control Lock Yes Softener Dispenser Yes Detergent Dispenser Yes Bleach Inlet Yes Auto Power Off Yes Smart Rinse with Jet Spray Yes Heater No ...

Page 4: ... noise and malfunctioning 1 Installation area Install the washer on a firm flat surface If the washer is installed on an unsuitable floor it could make considerable noise and vibrate 2 3 Checking level Open the lid check if the washer is correctly leveled by looking down from the top If the tub is not centered in the opening then the washer is not level WRONG RIGHT No shims It would be dangerous I...

Page 5: ...he drain hose and the wall Distance between the drain hose and the wall should be more than 4 inches 10 cm and the distance between any other part and the wall should be more than 1 inches 2 5 cm Do not install the washer in the following places Where the washer is exposed to direct sunlight Near a heater or heating appliance Where the washer is exposed to freezing temperatures In damp environment...

Page 6: ...ck water leakage After connecting the hose open the tap to check for any water leakage Connecting Water Supply Hose to the Machine Be sure there is a gasket in the end of the hose Connect the hose to the appropriate inlet vale hotorcold ofthewashingmachineandtightenif firmly Turn on the water and check for leacks Always install new hoses with a new washing machine Do not re use old hoses Relplace ...

Page 7: ...rain pipe to avoid siphoning and odor build up Cable Tie Cable Tie 35 47 0 9 1 2m 35 47 0 9 1 2m WARNING The washer should never be installed or stored in a location subject to freezing temperatures If the washer was exposed to freezing temperatures prior to installation allow it to stand at room temperature for several hours before use Damage to the water lines and internal mechanisms of the wash...

Page 8: ... HOT WATER SUPPLY HOSE Make sure the water does not leak POWER PLUG If the supply cord is damaged it must be replaced by the manufacturer or its service agents or similarly qualified person in order to avoid a hazard FUNCTION SELECTOR BASE DRAIN HOSE Be sure the drain hose is properly installed on the drain before operating the washer Smart Rinse with Jet Spray This washer is designed to save rins...

Page 9: ...mable materials waxes cleaning fluids etc Load Size The WATER LEVEL should just cover the clothes Adjust the load size accordingly Loosely load clothes no higher than the top row of holes in the washer tub To add items after washer has started press the START button and submerge additional items Close the lid and press the Start button again to restart Do not wash waterproofed fabrics such as skii...

Page 10: ...lors with light soil When washing in COLD water additional steps may be needed Adjust detergent amount and pre dissolve detergent in WARM water Pretreat spots and stains Soak heavily soiled items Use appropriate bleach Temperature below 18 C 65 F will not activate laundry additives and may cause lint residue poor cleaning etc In addition detergent manufactures and care labels define COLD water as ...

Page 11: ...ine bleach into the bleach dispenser During the final portion of the wash cycle two sequential flushes of the dispenser put all the bleach into the wash load and completely flush the dispenser to eliminate the carryover of bleach to a subsequent load Any liquid remaining in the bleach dispenser at the end of the cycle is water not bleach To prevent unintentional self siphoning of the bleach never ...

Page 12: ...most effective cleaning After adding the laundry products to the dispenser close the dispenser drawer Close the dispenser drawer gently to avoid spilling or starting the siphoning action To add detergent bleach and fabric softener to the automatic dispenser Open the dispenser drawer Load the laundry products into the appropriate compartments Close the lid slowly and smoothly to avoid spilling spla...

Page 13: ...ic softener Dilute with water to the maximum fill line Do not exceed the maximum fill line Overfilling can cause early dispensing of the fabric softener which could stain clothes NOTE Do not pour fabric softener directly on the wash load It may stain the clothes If you use an ultra thick fabric softener you might want to dilute it with water so it dispenses easily Adding Wash Boost Additives The w...

Page 14: ...umes may result Never wash items which have been previously cleaned in washed in soaked in or spotted with gasoline dry cleaning solvents or other flammable or explosive substances because they give off vapors that could ignite or explode Never use highly flammable solvents such as gasoline inside the home Vapors can explode on contact with flames or sparks For successful stain removal Remove stai...

Page 15: ... fabric Scrape residue from fabric Pretreat Wash using hottest water safe for fabric For heavy stains and tar apply nonflammable dry cleaning fluid to back of stain Replace towels under stain frequently Rinse throughly Wash using hottest water safe for fabric Some inks may be impossible to remove Washing may set some inks Use prewash stain remover denatured alcohol or nonflammable dry cleaning flu...

Page 16: ... will be adjusted accordingly POWER Power on Push again power goes off Power goes off automatically after the wash is finished After turning the power on the unit will automatically turn off if nothing is selected LOAD SENSING It operates in all cycles During being detected by the sensor the LOAD SENSING LED flashes It automatically sensing the size of the load During this step the washing machine...

Page 17: ...e end of the cycle The clothing should be removed at that time to prevent the setting of wrinkles Touch the SIGNAL button to cycle through the volume settings between OFF and high START PAUSE BUTTON Use to start or pause the wash cycle Changes while be made to the wash settings while the machine is paused Repeats start and pause by pushing the button CYCLE SELECTOR KNOB Use for selecting wash prog...

Page 18: ...water ONLY WASH SMALL LOADS to make sure there is plenty of room for the load to move during washing Keep like items together do not mix large bulky items with smaller clothing items Failure to follow these instructions may result in damage to the clothing or to the washer Heavy Duty Heavy soiled cotton fabrics Hot Extra High Heavy Warm High Normal Eco Warm Medium Light Cold Low Tap Cold No Spin P...

Page 19: ...mable DO NOT put them in washer or dryer Some pretreatment sprays or liquids can damage your washer s control panel Use of dyes in your washer may cause staining of the plastic components The dye will not damage the machine but we suggest you thoroughly clean your washer afterwards We do not recommend the use of dye strippers in your washer Do not use your washer lid as a work surface If Frozen Re...

Page 20: ...ch the ground wire on a regular basis to remove any static charge built up on your person 1 Remove front panel and main PCB assembly Remove 5 panel screws attaching the panel on the back Remove the rear panel Pull the front panel forward Disassemble the protective cover Disconnect the leads from the controller Remove 8 screws on the PCB assembly Remove the PCB assembly Rear Panel Main PCB Protect ...

Page 21: ...filter Inlet Valve Disconnect the leads from the inlet valve and remove three screws Remove the hoses and output pipes from the input valve Remove the inlet valve Pressure Switch Disconnect the leads from pressure switch and detatch the pressure switch from the machine Disconnect the pressure tube from the pressure switch Dispenser Housing Remove the hoses and output pipes from the input valve Dis...

Page 22: ...de between the cabinet and the top cover to release the latches Lift the top cover Use the blade to push the left hinge out of the way and to displace the hinge pin to remove the lid Remove the lid by pulling the right hinge pin out of its holder close open ...

Page 23: ...pulsator washer Tub Cover Pulsator Cap Pulsator Screw Pulsator Inner Tub Cap Hub Fixing Nut Outer Tub Inner Tub Stator Rotor Nut Hub Attachment Nut Shaft Bearing Housing ASM Rotor Inner Tub Cap Hit the bar using the hammer Disconnect hub nut and disassemble the inner tub 5 Assemble the service tool 38 mm wrench 6 Remove the hub attachment nut 38 mm ...

Page 24: ... top cover of the washing machine As shown in the drawing lift the damper assembly and remove it along with the outer tub assembly Damper assembly shall not be disassembled Replace damper as assembly 7 Disassembly of the Back Cover and Drain Pump Remove the screws that attach the back cover and take it off Disconnect the leads and the drain hose from the drain pump Remove the pump attachment screw...

Page 25: ...ng sure it faces the rotor and stator To keep from dropping the stator loosen the six bolts almost all the way then hold the stator in one hand while removing the bolts with the other Be careful during removal and replacement to avoid cutting nicking or pinching any of the wires This could cause a short or electrical noise in the machine Remove the screws that secure the water guide ...

Page 26: ...achment screws Remove the door switch and remove the attachment tube Remove 17 screws to release the bearing housing Pull the housing away from the tub but do not pry it with a screwdriver to avoid damage Remove four screws to release the tub bracket Bearing Housing ...

Page 27: ...4 2 WIRING DIAGRAM 27 WIRING DIAGRAM ...

Page 28: ...cient of flood sensing T5 and the coefficient of load sensing T6 and water level frequency T7 and the coefficient of load sensing T8 and RPM None Number of times the START PAUSE button is pressed Check Point Display Status 1 SAFETY CAUTION The main power board assembly has exposed live 120 VAC and live DC voltages Use care when disconnecting connectors during troubleshooting and testing Wear elect...

Page 29: ...ect amount of detergent for load size amount of soil and water hardness Use WARM or HOT water for normal soil Different water temperature may be required according to soil type refer to page 10 Reduce load size Wash with heavy or soak heavy wash cycle for heavy soiled laundry Separate heavily soiled items from lightly soiled ones Pretreat stain and heavy soil according to directions shown on page ...

Page 30: ...4 5 TROUBLESHOOTING SUMMARY 30 Pin1 Rx Pin2 Tx Pin3 Smps2_5v Pin4 GND Pin5 Pin6 Smps2_13v Pin7 Boot ...

Page 31: ...k the Presure Sensor 21 23 Ω 10 and connection 2 Check the Connector BL6 1 Check the connector of PCBA YL3 BL6 or motor connector or connection connector 2 Check the magnet for Rotor 3 Check the Rotor Resistance YL3 5 to 15 Ω U V V W W V U 1 V 2 W 3 1 Check the fuse for noise filter and PCBA by tester 2 Check the IPM Check the Short between top switch Heatsink and YL3 pin by Tester Check counterpl...

Page 32: ... running 120V 5 Stopped Motor Pump 0 1V Method 1 Enter the SERVICE Mode 2 Press START PAUSE button 1 time Main version 2 times Display version 3 times Inlet valve check mode 4 times Cold valve bleach valve 5 times Rinse valve hot valve 6 times Jet spray valve 7 times Heater check 8 times Alph check 9 times Pump check Note Environmental check list 1 The drainage hose must not stay in a lower positi...

Page 33: ... Is the resistance values in the range of 5 to15 Ω U V V W W V U 1 V 2 W 3 After pull out the YL3 connector check the terminal of the connector in wire No Replace the ROTOR Replace the STATOR Replace the Hall sensor Replace the MAIN PCB ASSEMBLY Part of motor Motor Hall Sensor Hall Sensor Hall Sensor Hall Sensor Hall Sensor Hall Sensor Hall Sensor Hall Sensor Hall Sensor Hall Sensor Hall Sensor Ha...

Page 34: ...Does the inlet valve work when the power is not applied Replace the INLET VALVE ASSEMBLY No Adjust the height of washing machine to be kept horizontally Yes If the inlet valve works continuously when the power is applied replace the MAIN PCB ASSEMBLY OVER FLOW ERROR Yes Is FE displayed Check the AIR CHAMBER and the tube clogged Yes When you enter the service mode is the water level frequency over ...

Page 35: ...onnected to pressure sensor disconnected or disassembled Yes Replace the pressure switch No Is the resistance of the pressure sensor out of range pin 1 pin 3 21 23 Ω 10 Yes No Is the AIR CHAMBER and the tube clogged Yes Fix the air chamber and remove the foreign material Replace the MAIN PCB assembly ...

Page 36: ... three pin wire of display PCB broken Yes Replace the MAIN PCB ASSEMBLY No Is LED on while the power is on Yes Check the fuse or reset the circuit breaker Yes Is the supplied voltage 120V AC 10 15 No Reconnect or repair the connector Yes Is the connector connected to PCB Noise filter disconnected or disassembled No Alternate with explanation Yes Is the current rating of multi outlet power strip en...

Page 37: ...nd and LED light while touch the LCD Yes Yes No Is the connector connected to Main PCB Display PCB disconnected or disassembled Reconnect or repair the connector Connecting connector Main PCB Display PCB POWER BUTTON DOESN T WORK Yes No Is the button of panel stuck Repair the button ...

Page 38: ...cking the component be sure to turn the power off and do voltage discharge sufficiently Wiring diagram Test points and Result Circuit in the MAIN PCB Wiring Diagram MAIN PCB ASSEMBLY 3 3 1 1 RD1 WH1 Vac 1 1 2 2 2 2 Test Points WH 1 to RD 1 WH 3 to RD 2 Result 0 Ω 0 Ω 1 3 1 2 RD1 WH1 WARNING ...

Page 39: ...etected when switch sensing point is detected lock position The motor stops Door locked The maximum allowable number of impulse authorizations is 3 Upon the third authorization of the impulse the position of hook goes back to the door open position Authorizing the impulse occurs in 4 5 seconds upon input for max performance and two authorization processes are allowed at most 2 Operation for door o...

Page 40: ...Result 33 46 Ω 9 11 AT 40 Test points Result Test Points 1 To 2 1 Black 2 Brown 4 To 5 4 White 5 Green 1 2 3 4 5 6 ...

Page 41: ...ed to maximum speed in infinite steps in either direction There are 36 poles on the stator 12 permanent magnets spaced around the rotor There are no brushes to wear out Unlike a more traditional brushless motor the rotor surrounds the stator rather than being attached to it Result 5 15 Ω 5 15 Ω 5 15 Ω Test Points 1 to 2 2 to 3 3 to 1 WINDINGS 1 HALL SENSOR 3 2 ...

Page 42: ...carefully move test leads to terminals 1 to 4 blue and gray Slowly rotate motor rotor by hand You should read a pulsing 10 Vdc If 10 Vdc is measured from 1 to 4 move lead on blue wire to red wire terminal 2 Repeat rotating motor rotor by hand You should read a pulsing 10 Vdc from red to gray 8 If pulsing 10 Vdc is measured from 1 to 4 and 2 to 4 hall sensor is OK If either test netted only 9 to 10...

Page 43: ...5 Vdc is measured the control board is defective 8 Place meters leads on Blue to Yellow Turn motor rotor slowly by hand You should measure a pulsing 10 Vdc Place meter leads on Red to Yellow Turn motor rotor slowly by hand You should measure a pulsing 10 Vdc If both tests measure a pulsing 10 Vdc hall sensor and harness OK If either or both tests measures 9 to 10 volts but does not pulse or change...

Page 44: ...5 4 PUMP MOTOR ASSEMBLY 44 Wiring diagram Test points and Result Circuit in the MAIN PCB Wiring Diagram 1 2 Result 10 9 Ω 5 Remarks Resistance Test Points 1 to 2 ...

Page 45: ...t valve driving circuit Depending on the cycle and water temperature the controller will energize the hot or cold water valve solenoids to meet the selected water temperature After unplugging the connector of the defective valve check the resistance 1 2 2 2 2 2 1 1 1 1 All valves operate at 13 5 VDC Test Points 1 2 Result 24 10 Ω ...

Page 46: ...HERMISTOR ASSEMBLY 46 Wiring diagram Function Test points Circuit in the MAIN PCB Wiring Diagram Wash Thermistor The thermistor temperature sensor is used to monitor water temperature in the tub MAIN PCB 2 1 ...

Page 47: ...it standard The upper limit 70 519 46 997 22 285 15 803 6 984 5 180 76 531 50 584 23 623 16 635 7 471 5 573 82 848 54 307 24 978 17 467 7 971 5 981 Test Points 1 to 2 Remarks Result At 86 30 At 104 40 At 140 60 At 158 70 At 203 95 At 221 105 ...

Page 48: ...6 EXPLODED VIEW 48 BODY A BODY B ...

Page 49: ...COVER ASSEMBLY 49 A100 A140 A157 A020 A148 A050 A062 A056 A061 A063 A200 A202 A230 A410 A241 A105 A240 A180 A186 A183 A184 A390 A380 A125 A147 A190 A011 A150 A151 A153 A154 A152 A101 This is old non slide type of Top Cover A101 ...

Page 50: ...032 F000 F017 F018 F011 F100 F100 The replacement parts in this kit may be different than the original Replace all the original drain hose parts with these new parts F090 F102 F103 F104 F105 F102 5 These are old mold type of Hanger Pivot F001 F001 This is old non slide type of cabinet ...

Page 51: ...6 3 EXPLODED VIEW OF TUB ASSEMBLY 51 K000 K005 K100 K250 K060 NATURAL K340 K345 K200 K210 K201 K305 K300 K170 K290 K230 K050 K350 K430 K040 K012 K030 K020 K021 K061 K064 K140 ...

Page 52: ...7 REPLACEMENT PART LIST 52 ...

Page 53: ...P No MFL40322153 Mar 2012 PRINTED IN KOREA ...

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