LG WT4901C Series Service Manual
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LG WT4901C Series Service Manual

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

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Summary of Contents for LG WT4901C Series

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

  • Page 2: Table Of Contents

    SAFETY PRECAUTION! IMPORTANT SAFETY NOTICE! This service information is intended for individuals possessing adequate backgrounds of electrical, electronic, and mechanical experience. Any attempt to repair this appliance may result in personal injury or property damage. The manufacturer or seller can not be responsible for the interpretation of this information, nor can it assume any liability in connection with its use.

  • Page 3: Specifications

    1. SPECIFICATIONS Model WT4901C*/WT4970C* Electrical 120 VAC@60 Hz. Inner Tub Stainless Inlet Water Pressure 14.5 ~ 116 PSI (100 ~ 800 kPa) Rating of Fuse 120V/60Hz Spin Speed 1100±50 rpm Weight 145.5 lbs (66kg) Cotton/Normal, Perm Press, Heavy Duty, Bulky/Bedding, Cycles Bright WhitesTM, Tub Clean, Speed Wash, Delicates Time Delay...

  • Page 4: Installation Instructions

    2. INSTALLATION INSTRUCTIONS 2-1. HOW TO ADJUST LEVEL Raise Lower Installation area Checking level Install the washer on a firm, flat • Open the lid, check if the washer is • surface. correctly leveled by looking down If the washer is installed on an •...
  • Page 5 Horizontal setting Distance between the drain hose and the wall • If the washer is not level, adjust the leveling feet. Turn clockwise to raise, Distance between the drain hose and • counterclockwise to lower. the wall should be more than 4 inches (10 cm,) and the distance between any side to side other part and the wall should be more...

  • Page 6: Connecting Water Supply Hose

    2-2. CONNECTING WATER SUPPLY HOSE Before connecting the water supply hose to the water tap, check the hose type and then choose the correct instruction here below. Screw Type Be sure there is a gasket in both ends of the hose. Push the water supply hose up so that the rubber packing Water tap within the hose can adhere completely to the tap.

  • Page 7: Connect The Drain Hose

    2-3. CONNECT THE DRAIN HOSE • Connect the drain hose to the • And then push it toward the body of • Check that the drain hose is hung outlet of the drain pump located at the washing machine as indicated up over the edge of the laundry tub.

  • Page 8: Operating Instructions

    3. OPERATING INSTRUCTION 3-1. IDENTIFICATION OF PARTS CoLd wAter SUPPLY HoSe Hot wAter SUPPLY HoSe Make sure the water Powder detergent does not leak. Box for delayed washing/softener additves box FUnCtIon SeLeCtor Power PLUg If the supply cord is damaged, it must be replaced by the manufacturer or its service agents...

  • Page 9: Before Starting To Wash

    3-2. BEFORE STARTING TO WASH Care Labels • Look for a care label on your clothes. This will tell you about the fabric content of your garment and how it should be washed. Sort clothes into loads that can be washed with the same wash cycle, water temperature, and spin speed.
  • Page 10 1) Using Water Water Temperature • The machine sets the appropriate temperature automatically according to the wash program . You can override the preset selection by pressing the water temperature icon. Touch the arrow buttons up or down until your desired temperature setting is displayed. •...
  • Page 11 2) Using Detergent Detergent Follow the detergent package directions. Using too little detergent is a common cause of laundry problems. Use more detergent if you have hard water, large loads, greasy or oily soils or lower water temperature. Choosing the Right Detergent Your washing machine is designed for use with only High-Efficiency (HE) detergents.
  • Page 12 Using the Dispenser Drawer ABOUT THE DISPENSER Main Wash Main Wash Powder Detergent Liquid Detergent The automatic dispenser consists of two Compartment Compartment compartments which hold: • Liquid fabric softener. Liquid Fabric • Liquid or powdered detergent. Softener All laundry products can be added at once in their respective Compartment dispenser compartments.
  • Page 13 Adding Detergent Add measured detergent to the detergent compartment of the dispenser drawer. • Do not exceed the maximum fill line. Detergent is flushed through the dispenser at the beginning of the wash cycle. Either powdered or liquid detergent can be used, but the drawer insert must be removed to use powder.
  • Page 14 3) Special Guide for Stain Removal WARNING Do not use or mix liquid chlorine bleach with other household chemicals such as toilet cleaners, rust removers, acid, or products containing ammonia. These mixtures can produce dangerous fumes which can cause serious injury or death. To reduce the risk of fire or serious injury to persons or property, comply with the basic warnings listed below: •...
  • Page 15 Stain Removal StAIn treAtMent Adhesive tape, chewing Apply ice. Scrape off excess. Place stain face down on paper towels. Saturate with gum, rubber cement prewash stain remover or nonflammable dry cleaning fluid. Baby formula, dairy Use product containing enzymes to pretreat or soak stains. products, egg Beverages (coffee, tea, soda, Pretreat stain.

  • Page 16: Function Of Each Button

    3-3. FUNCTION OF EACH BUTTON POWER LOAD SENSING · It operates in all cycles. · Power on. · During being detected by the sensor, the LoAD · Push again, power goes off SENSING LED flashes. · Power goes off automatically after the wash ·...
  • Page 17 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 program. ·...

  • Page 18: Washing Programs

    3-4. WASHING PROGRAMS. Cycle guide The cycle guide below shows the options and recommended fabric types for each cycle. =Default setting STAIN Extra Water Fabric Cycle Fabric Type Wash Temp. Spin Speed Soil Level Soak COLDWASH CARE Rinse Plus Softener High Tub Clean Refer to page 29.

  • Page 19: Care And Maintenance

    3-5. CARE AND MAINTENANCE When There Is The Possibility Of Freezing Temperatures • Close the water taps and remove the water supply hoses. • Remove the water which remains in the water supply. • Lower the drain hose and drain the water in the sump and the drain hose by running a spin cycle. If Frozen •...

  • Page 20: Service Information

    4. SERVICE INFORMATION 4-1. DISASSEMBLY INSTRUCTION ▶ 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.
  • Page 21 2) Disassembly of the Noise Filter, Ⓐ Ⓑ Ⓒ Power Cord, Inlet Valve, Pressure Switch, and Dispenser Housing. Ⓓ Noise Filter and Power Cord ① Remove the two screws attaching the noise filter. ② Disconnect both connectors in the noise filter. Remove the power cord from the noise filter.
  • Page 22 3) Disassembly of Top Cover and Lid ① Insert a flat blade between the cabinet and the top cover to release the latches. ②Lift the top cover. ③ Use the blade to push the left hinge out of the way and to displace the hinge pin to remove the lid.
  • Page 23 Inner Tub Cap Hub Fixing Nut Tub Cover Outer Tub Inner Tub Pulsator Cap Pulsator Shaft Bearing Housing ASM Screw Rotor Rotor Nut Stator Pulsator Inner Hub Attachment Nut Tub Cap 4) Disassembly of Tub Cover and Pulsator ① Remove 8 screws and take off the tub cover. ②...
  • Page 24 7) Disassembly of the Back Cover and Drain Pump ① Remove the screws that attach the back cover and take it off. ② Disconnect the leads and the drain hose from the drain pump. ③ Remove the pump attachment screws and the lead connector.
  • Page 25 ③ Remove the screws that secure the water guide. ④ Disconnect the hall sensor and stator connection before removing the stator in the subsequent step. ⑤ Remove the six screws securing the rotor. ⑥ Check the position of the snap ring, being sure it faces the rotor and stator.
  • Page 26 ⑨ Remove four screws to release the tub bracket. ⑩ 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. Bearing Housing 9) Disassembly of Door Lock Switch Remove the two door lock attachment screws.

  • Page 27: Wiring Diagram

    4-2. WIRING DIAGRAM...

  • Page 28: Test Running Without Water

    4-3. TEST RUNNING WITHOUT WATER 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 electrostatic discharge gloves when handling the board. •...

  • Page 29: Troubleshooting By Common Washing Problems

    4-4. TROUBLESHOOTING BY COMMON WASHING PROBLEMS Many washing problems involve poor soil and stain removal, residues of lint and scum, and fabric damage. For satisfactory washing results, follow these instructions. Use ONLY powdered or liquid HE (High Effificiency) detergents. Do NOT use flakes scraped from a soap cake or bar, flakes, soap ribbons (available in some markets,) detergent tablets, plastic pouches, magic laundry balls, or anything other than powdered or liquid HE detergent products.

  • Page 30: Troubleshooting Summary

    4-5. TROUBLESHOOTING SUMMARY...

  • Page 31: Troubleshooting With Error Code

    4-6. TROUBLESHOOTING WITH ERROR CODE Trouble Check counterplan 1. Verify the valve is open and water is on. 1. Turn the tap on. 2. Check the filter on inlet valve whether 2. Clean or replace the filter clogged with foreign material or not. 3.
  • Page 32 DRAIN ERROR Is OE displayed? Is the connector connected to Replace the Reconnect or Is the coil of the drain pump pump motor assembly DRAIN PUMP repair the too high or low? (resistance of disconnected or ASSEMBLY. connector the coil is 10-20 Ω) disassembled? Is the voltage between Replace the...
  • Page 33 LOCKED MOTOR ERROR - Part of motor Is LE displayed? Reconnect Check the connectors below. the connector Is the connector disconnected Motor (connector / or disassembled? wire / motor ) (motor hall sensor connector, motor drive connector) Is rotor magnet cracked? - Part of main PCB assembly (YL3, BL6) Replace the...
  • Page 34 UNBALANCE ERROR OVER FLOW ERROR Is UE displayed? Is FE displayed? Does the laundry lean toward When you enter the service Put laundry evenly Check the AIR one side, not evenly put in the mode, is the water level In the DRUM CHAMBER and the DRUM assembly? frequency over 21.0 kHz?
  • Page 35 PRESSURE SENSOR ERROR Is PE displayed? Is the connector connected to Reconnect or pressure sensor disconnected repair the or disassembled? connector Is the resistance of the Replace the pressure sensor out of range? pressure switch (pin 1~ pin 3) (21~23 Ω±10%) Fix the air Is the AIR CHAMBER and the chamber and...

  • Page 36: Other Troubleshooting

    4-7. OTHER TROUBLESHOOTING CAUTION 1. Be careful of electric shock if disconnecting parts while troubleshooting. 2. First of all, check the connection of each electrical terminal with the wiring diagram. 3. If you replace the main PCB assembly, reinsert the connectors correctly. NO POWER Is LED on while the power is Replace the MAIN...
  • Page 37 POWER BUTTON DOESN’T WORK Is the connector connected to Reconnect or Replace the Is the display PCB broken? Main PCB / Display PCB repair the DISPLAY PCB (check the buzzer sound and ASSEMBLY disconnected or connector LED light while touch the disassembled? LCD) Connecting connector...

  • Page 38: Component Testing Information

    5. COMPONENT TESTING INFORMATION WARNING When resistance (Ohm) checking the component, be sure to turn the power off, and do voltage discharge sufficiently. 5-1. Filter Assembly (Line Filter) Circuit in the MAIN PCB / Wiring Diagram Wiring diagram MAIN PCB ASSEMBLY Test points...

  • Page 39: Door Lock Switch Assembly

    5-2. Door Lock Switch Assembly. Circuit in the MAIN PCB / Wiring Diagram Wiring diagram The Door Lock Switch Assembly consists of a DC Motor, a Bimetal, a Protection PTC, Sensing Point. It locks the door during a wash cycle. 1.
  • Page 40 Test points Test Points Result (1)To (2) 33 ~ 46 Ω Result (1)-Black / (2)-Brown (4) To (5) 9 ~ 11 AT (4)-White / (5)-Green...

  • Page 41: Stator Assembly

    5-3. STATOR ASSEMBLY Circuit in the MAIN PCB / Wiring Diagram Wiring diagram The DD motor can be driven from stopped 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 Function brushes to wear out.
  • Page 42 The hall sensor determines the speed and direction of the motor. It also can read that the load is off balance when the drum speed fluctuates. - Voltage Testing Hall Sensor at Stator If measuring voltage from the Main PCB Assembly to the Hall Sensor, use the following steps: 1.
  • Page 43 - Voltage Testing Hall Sensor from the Main PCB Assembly 1. Unplug power cord. 2. Remove rear panel. 3. Remove Washer Top. 4. Remove Main PCB Assembly cover as shown in Figure below. 5. Locate the Blue Hall Sensor 6 wire connector using wiring diagram wire colors as your guide. 6.

  • Page 44: Pump Motor Assembly

    5-4. PUMP MOTOR ASSEMBLY Circuit in the MAIN PCB Wiring Diagram Wiring diagram Test Points Result Remarks (1) to (2) 10.9 Ω±5% Resistance Test points Result...

  • Page 45: Inlet Valve Assembly

    5-5. INLET VALVE ASSEMBLY Circuit in the MAIN PCB Inlet valve driving circuit Wiring diagram Wiring diagram INLET VALVE * All valves operate at 13.5 VDC. Depending on the cycle and water temperature, the controller will energize the hot or cold water Function valve solenoids to meet the selected water temperature.

  • Page 46: Thermistor Assembly

    5-6. THERMISTOR ASSEMBLY Circuit in the MAIN PCB / Wiring Diagram Wiring diagram MAIN PCB The thermistor (temperature sensor) is used to monitor water temperature in the tub. Function Test points Wash Thermistor...
  • Page 47 Wash Thermistor Result [㏀] Test Points Remarks The lowest standard The upper limit limit 70.519 76.531 82.848 At 86℉ (30℃) (1) to (2) Result 46.997 50.584 54.307 At 104℉ (40℃) 22.285 23.623 24.978 At 140℉ (60℃) 15.803 16.635 17.467 At 158℉ (70℃) 6.984 7.471 7.971...

  • Page 48: Exploded View

    6. EXPLODED VIEW BODY-A BODY-B...
  • Page 49 6-1. EXPLODED VIEW OF TOP COVER ASSEMBLY A011 A056 A063 A061 A062 A240 A202 A050 A200 A148 A180 A184 A390 A020 A152 A183 A154 A186 A153 A151 A147 A150 A241 A410 A105 A230 A100 A190 A125 A380 A157 A140 (A101)This is old (non slide) type of Top Cover A101...
  • Page 50 6-2. EXPLODED VIEW OF OUT CASE ASSEMBLY F102 F103 F104 F105 F018 F032 F011 (F102~5) These are old (mold) type of Hanger Pivot F017 F070 F000 F090 (F100) The replacement parts in this kit may be different than the original. Replace all the original drain hose parts with these new parts.
  • Page 51 6-3. EXPLODED VIEW OF TUB ASSEMBLY K005 K000 K012 K021 K020 K030 K040 K050 K061 K060 NATURAL K100 K250 K350 K064 K140 K170 K345 K340 K200 K290 K230 K210 K201 K305 K430 K300...

  • Page 52: Replacement Part List

    7. REPLACEMENT PART LIST...
  • Page 53 Mar. 2012 PRINTED IN KOREA P/No.: MFL40322153...

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Wt4970c series

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