LG LFC20760 Series Service Manual Download Page 28 | Manualshive

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2. Motors driving circuit (freezing compartment fan)

1. The circuit makes the Motor Fan OFF by cutting Off the power supplied to driver inside the Fan Motor when the is necessary.

2. This is a circuit to perform a temporary change of speed for the fan motor and applies DC voltage up to 7.5V ~ 16V to motor .

3. This circuit prevents over-driving the fan motor by cutting off power applied to the fan motor in the lock of fan motor by

sensing the operation RPM of the fan motor.

part

part

MOTOR OFF

2V or less

0V

MOTOR ON

13V~15V

0V

a

b

3. Cooling motor driving circuit (machine room)

1. This circuit makes standby power 0 by cutting off power supplied to Iss inside of the fan motor in the fan motor OFF.
2. This circuit prevents over-driving the fan motor by cutting off power applied to the fan motor in the lock of fan motor by
sensing the operation RPM of the fan motor.

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Summary of Contents for LFC20760 Series

Page 1: ...CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL REFRIGERATOR SERVICE MANUAL MODELS LFC20760 https appliancetechmanuals com ...

Page 2: ...FETY PRECAUTIONS SAFETY PRECAUTIONS 1 SPECIFICATIONS 2 PARTS IDENTIFICATION 3 DISASSEMBLY 3 1 Door 3 2 Door alignment 3 3 Fan and fan motor 3 4 Defrost control assembly 3 5 Lamp 3 6 Control box refrigerator 3 7 Multi duct 4 ADJUSTMENT 4 1 Compressor 4 2 PTC Starter 4 3 OLP Overload Protector 4 4 To remove the cover PTC 5 CIRCUIT DIAGRAM 6 TROUBLESHOOTING 6 1 Compressor and electrical components 6 ...

Page 3: ... YES 2 40W blue GUIDE BOTTLE YES 2 DOOR COOOLING NO TRAY VEGETABLE YES NORMAL 270 28 GENERAL FEATURES CAPACITY CUFT F R T R134a 120 3 ICE TRAY SHELF SPECIFICATIONS DIMENSIONS in W H D FREEZER REFRIGERATOR WEIGHT lb Ice bank 1ea BASKET DOOR 3LEFT 3RIGHT REFRIGERANT gr MODELS NO LFC20760ST LFC20760SW LFC20760SB 6 39 13 21 19 6 29 88 68 43 32 17 https appliancetechmanuals com ...

Page 4: ...oor Depth Total with Door Open Height to Top of Case Height to Top of Door Hinge Width Width door open 90 deg w o handle Width door open 90 deg w handle A B C D E F G H I Description LFC20760 34 32 28 44 29 32 37 67 7 16 68 5 8 https appliancetechmanuals com ...

Page 5: ...f the features shown below may not match your model on some models A B C G H I J E F K D L M N O P A L Digital Sensor Control Filter Inside Durabase Divider Egg Box Refrigerator Door Rack Freezer Light Pull out Drawer B C D F E G H I J K M N O P Ice Tray Optibin Crisper Keeps fruits and vegetable fresh and crisper Chef Fresh Snack Pan Can Dispenser Shelves Refrigerator Light Customcube Icemaker Da...

Page 6: ...maining two clips until you hear each snap securely into place Note Make sure that no part of gasket bracket edge protrudes from beneath door frame edge 3 DISASSEMBLY 5 Frame Cover Handle Gasket Door Bracket Clip Frame Flat Tip Screwdriver Gasket Bracket Figure 3 Figure 1 Figure 2 Figure 4 Gasket Bracket Clip Spring Door Frame Correct Incorrect Figure 5 Left Door Loosen the cover screw 1 Disconnec...

Page 7: ...ng down snap cover back into door 3 2 DOOR ALIGNMENT If the space between your doors is uneven follow the instructions below to align the doors 1 With one hand lift up the door you want to raise at middle hinge 2 With other hand use pliers to insert snap ring as shown 3 Insert additional snap rings until the doors are aligned Three snap rings are provided with unit 6 Figure 6 Correct Incorrect Fig...

Page 8: ...e 14 Max 40 W2EA 3 5 2 Freezer Compartment Lamp figure 15 1 Unplug refrigerator or disconnect power 2 Reach behind light shield to remove bulb 3 Replace bulb with a 40 watt appliance bulb 4 Plug in refrigerator or reconnect power 3 6 CONTROL BOX REFRIGERATOR 1 First remove all shelves in the refrigerator than remove the Refrigerator control Box by loosening 2 screws 2 Remove the Refrigerator Contr...

Page 9: ...ng and main winding 4 2 3 PTC Applied Circuit Diagram Starting Method for the Motor 4 2 4 Motor Restarting and PTC Cooling 1 It requires approximately 5 minutes for the pressure to equalize before the compressor can restart 2 The PTC device generates heat during operation Therefore it must be allowed to cool before the compressor can restart 4 2 5 Relation of PTC Starter and OLP 1 If the compresso...

Page 10: ... way 4 4 TO REMOVE THE COVER PTC 1 Remove the Cover Back M C 2 Disconnect two housing upper side of comp connected in 3 Loosen two screws on comp base 4 Use a L shaped flap tool to pry off the cover 5 Assembly in reverse order of disassembly 9 Part Customer part number Lot code date code 330 FBYY S1 BOX98 12345678 Physical termination part number Electrical characteristics part number No Name Base...

Page 11: ... C FUSE M I MAKER W VALVE BK V S W Cr RD PK 2 2 CAPACITOR PART CAPACITOR PART CON6 1 BL 2 1 RD BK 5 5 6 6 4 4 3 3 PTC STARTER Cs BL COMP ACCESSORIES POWER PK PINK YL YELLOW BK BLACK GN GREEN BN BROWN PWB PCB ASSEMBLY ICE MAKER WH WHITE BL FUSE M BL B A HEATER SHEATH BO RD 72 C nc BK OLP YL S GN PART PART S GN YL M COMP EARTH COMP EARTH GN GN BL PR F LAMP nc R LAMPS D C BL nc PR PURPLE BO BRIGHT OR...

Page 12: ...hecked by an electrician Replace Compressor Supply voltage rating with 10 Applied voltage isn t in acceptable range 115V 10 Remove PTC Starter from Compressor and measure voltage between Terminal C of Compressor and Terminal 5 or 6 of PTC Check resistance between M C S C and M S in Motor Compressor Check resistance of two terminals in PTC Starter Check resistance of two terminals in OLP Check the ...

Page 13: ...between No 5 and 6 of PTC Starter with a Tester Figure 19 Separate OLP from Compressor and check resistance value between two terminals of OLP with a Tester Figure 20 Observation value is 115V 60Hz 6 8 30 The resistance value is 0 short or open Check another electric component Replace OLP Replace PTC Starter Figure 19 Figure 20 https appliancetechmanuals com ...

Page 14: ... indicated component Advise customer that the Power supply needs to be checked by an electrician Replace indicated component Cause Check voltage at starting devices Check current flowing in sub coil of Compressor Check rating of OLP Fan motor doesn t run Heavy frost buildup on EVAPORATOR Wire is open or shorted Coil is shorted or open Open Open Replace Defrost Heater Replace indicated component Re...

Page 15: ...ap in the door gasket Is the unit positioned in a firm and even place Are any unnecessary objects placed in the back side of the unit Check if the Drip Tray is not firmly fixed Check if the cover of the compressor enclosure in the lower front side is taken out Check if the door gasket is dirty with an item like juice Is the refrigerator level Is there too much food in the refrigerator Check if the...

Page 16: ...nlet only temperature The capillary tube is faulty cool normally WHOLE Freezer Flowing sound of refrigerant Equal to ambient Normal discharging of the CLOG compartment and is not heard and frost isn t temperature Refrigerant Refrigerator don t cool formed MOISTURE Cooling operation Flowing sound of refrigerant Lower than Cooling operation restarts CLOG stops periodically is not heard and frost mel...

Page 17: ...efficient Compressor Partial Restriction Complete Restriction Equalization Test Condenser Temperature None Very Fast Very Slow Very Slow Hotter than Normal Air Low Side Leak Loss of Change Compressor Not Pumping Cap Tube Sound Room Temperature Trace of Oil Undercharge Leak Yes No Faint Fast None to Weak The equalization test is trying to restart a compressor using a start kit after it has been ope...

Page 18: ... Fill Test Mode Waits until water becomes cold after starting the Icemaking operation Runs MOTOR to drop ice from the tray into the ICE BIN Performs Icemaking Mode after supplying water by operating the SOLENOID in ICE VALVE To operate LINE and SERVICE press and hold the Cube Size button for 3 seconds The icemaking will run through 3 stages Harvest Fill Icemaking With the detect lever checks if th...

Page 19: ... start position again while Heater Motor are on at the same time A ice bin is full The EJECTOR stops heater off B ice bin is not full The EJECTOR rotates twice to open for ice NOTE If the EJECTOR does not rotate once within 5 minutes in status 2 separate heater control mode starts operating to prevent the EJECTOR from being constrained It is recommended that the user open for ice to return to norm...

Page 20: ... panel ERROR indicators in table can be checked only in TEST mode STAGE ITEMS INDICATOR REMARKS 1 2 3 4 5 6 HEATER MOTOR HALL IC TRAY SOLENOID VALVE HALL IC LEVER Reset Five seconds after heater starts heater will go off if temperature recorded by sensor is 10 C 50 F or lever is in up position Five seconds after heater starts you can confirm that motor is moving You can confirm Hall IC detection o...

Page 21: ... PLUS operates for the rest of time after defrost is completed when ICE PLUS operation time is less than 90 minutes If ICE PLUS operates for more than 90minutes the ICE PLUS will operate for two hours after defrost is completed 3 If ICE PLUS is pressed during defrost ICE PLUS LED is on but this function will start seven minutes after defrost is completed and it shall operate for three hours 4 If I...

Page 22: ...r temperature reaches 46 4 F 8 C or more If the sensor doesn t reach 46 4 F 8 C in a hour the defrost mode is malfunctioning 4 Defrosting won t function if its sensor is defective wires are cut or short circuited OPERATING ORDERS Initial power on Temperature of Defrosting Sensor is 45 C or more when unit is newly purchased or when moved POWER ON In second COMP ON In second Freezer FAN ON In second...

Page 23: ...wires on each sensor Snapping of defrost heater or Temperature fuse pull out of Connector indicated minimum 1 Hours after failure occurs All off All off All off All off All off LED OFFLED ON 1 hours later after Open or short circuit Visible in LED CHECK MODE starting defrost If sensor doesn t be over 46ºF 8ºC 5 Failure of BLDC fan motor at freezing compartment DISPLAY CHECK MODE Press at the same ...

Page 24: ...ds Or press TEST S W one time in the Main PCB board Push ICEPLUS key and ADJUST key of Freezer temperature at the same time over 3 seconds being in TEST MODE1 Or press TEST S W one time being in TEST MODE 1 Push ICEPLUS key and ADJUST key of Freezer temperature at the same time over 3 seconds being in TEST MODE2 Or press TEST S W one time being in TEST MODE 2 1 Continuous operation of the COMPRESS...

Page 25: ... MICOM and IC 5 Vdc The voltage for each part is as follows VA1 is a part for preventing over voltage and noise When high voltage is applied the inside elements are short circuited and broken resulting in blowout of the fuse in order to protect the elements of the secondary part of the TRANSFORMER PART VA 1 CE 3 CE 4 CE 5 VOLTAGE 115 Vac 12 Vdc 15 5 Vdc 5 V https appliancetechmanuals com ...

Page 26: ...3 Reset Circuit The RESET circuit allows all the functions to start at the initial conditions by initializing various parts including the RAM inside the MICOM IC1 when the power is initially supplied or the power supply to the MICOM is restored after a momentary power failure For the initial 10ms of power supply LOW voltage is applied to the MICOM RESET terminal During a normal operation 5V is app...

Page 27: ...oor Detection Circuit 1 Load Drive Condition Check LOAD TYPE COMP NO 14 NO 12 NO 11 NO 13 1V or below 12V DEFROSTING HEATER LAMP FRENCH DOOR HEATER 1 2 DEW HEATER Measurement Location IC6 Condition ON OFF https appliancetechmanuals com ...

Page 28: ...an motor by cutting off power applied to the fan motor in the lock of fan motor by sensing the operation RPM of the fan motor part part MOTOR OFF 2V or less 0V MOTOR ON 13V 15V 0V a b 3 Cooling motor driving circuit machine room 1 This circuit makes standby power 0 by cutting off power supplied to Iss inside of the fan motor in the fan motor OFF 2 This circuit prevents over driving the fan motor b...

Page 29: ...eep OFF 0 05 s 0 1 s 0 2 s 2 s 0 V 5 V 0 V 5 V 2 63 kz Ding 2 21 kz Dong A B Tone Ding Dong when the button on the display is pushed Alarm for open door beep beep beep Pin No 14 Refrigerator Door Pin No 15 Freezer Door Closed 5 V Open 0 V Freezer Refrigerator Door Measurement Location REFRIGERATOR DOOR SWITCH FREEZER DOOR SWITCH https appliancetechmanuals com ...

Page 30: ... defrosting and the indoor temperature for compensating for the surrounding temperature into MICOM OPENING or SHORT state of each TEMPERA TURE SENSOR are as follows 8 2 6 Refrigeration Compartment Stepping Motor Damper Circuit The circuit shown below is the damper circuit to regulate the refrigerator temperature https appliancetechmanuals com ...

Page 31: ...R 2 deg compensation Example 2 CUTTING JCR1 and JCR3 no compensation in R compartment Example 3 CUTTING JCR1 JCR2 and JCR3 compensation of temp 1deg 1deg 1deg 8 2 9 Key Button Input Display Light On Circuit The circuit shown above determines whether a function control key on the operation display is pushed It also turns on the corresponding function indication LED LED Module SEVEN SEGMENT DISPLAY ...

Page 32: ...suring temperature This delay is necessary due to sensor response speed Measure the F SENSOR SUPER FROST SENSOR R1 R2 SENSOR after disconnect CON5 of PWB AS SY MAIN TEMPERATURE DETECTED RESISTANCE OF FREEZER RESISTANCE OF REFRIGERATOR BY SENSOR SENSOR DEFROST SENSOR ROOM SENSOR 20º C 15º C 10º C 5º C 0º C 5º C 10º C 15º C 20º C 25º C 30º C 40º C 50º C https appliancetechmanuals com ...

Page 33: ...e OLP PTC after compressor shuts off COMPRESSOR RELAY is Replace MAIN PWB don t press the KEY and poor wait THE CONNECTING WIRE Check the connection of the is poor black wire of the MAIN PWB CONNECTOR CON2 2 If refrigerant is leaking Measure the amount of frost Refrigerant leakage Replace the leaking part and sticking on EVAPORATOR replace any lost refrigerant and the surface temperature of the co...

Page 34: ...place Door liner door is closed DEFROSTING is NO DEFROSTING 1 If HEATER emits heat USE TEST MODE3 HEATER disconnection Replace HEATER poor forced DEFROSTING TEMPERATURE FUSE Replace TEMPERATURE disconnection FUSE Connection is poor Check EVAPORATOR connection and wire of MAIN PWB CONNECTOR DEFROST SENSOR is poor Replace DEFROST SENSOR HEATER RELAY is poor Replace RY2 of MAIN PWB 2 If DRAIN PIPE is...

Page 35: ...8 5 MAIN PWB ASSEMBLY AND PARTS LIST 8 5 1 Main PWB Assembly 34 TOP VIEW BOTTOM VIEW https appliancetechmanuals com ...

Page 36: ...8 5 2 Replacement Parts List 35 https appliancetechmanuals com ...

Page 37: ...8 5 3 PWB Assembly Display and parts list 36 https appliancetechmanuals com ...

Page 38: ...8 6 PWB DIAGRAM 8 6 1 PWB Main Assembly 37 https appliancetechmanuals com ...

Page 39: ... 38 https appliancetechmanuals com ...

Page 40: ...406B 328A 105A 317A 318A 307A 314A 312A 420A 327A 310A 308A 309A 410G 323B 329C 319A 319C 106A 328B 305B 305C 305B 305C 903B 903A 903B 103C 105F 405G 329A 319E 405C 404A 405F 405A 332A 135C S22 158E 418A 106A 409B 315A 9 EXPLODED VIEW AND REPLACEMENT PARTS LIST EV 412D 405B 405B CASE PARTS CAUTION use the part number to order part not the position number 39 S38 https appliancetechmanuals com ...

Page 41: ...131A 136B 248E 248F 136A 237C EV FREEZER PARTS CAUTION Use the part number to order part not the position number 40 145F 145C https appliancetechmanuals com ...

Page 42: ...D 140B 103E 167B 154A 151A 151A 103E 155B 151C 41 EV REFRIGERATOR PARTS CAUTION Use the part number to order part not the position number 140D S24 S24 140E 143E 140B 140D S24 S24 140E 143E 140B 140D S24 S24 140E 143E 140B https appliancetechmanuals com ...

Page 43: ...7A 233G 233E 244A 212J 286A 286A 243A 243A S27 S27 243B 243B 262E 262E 233H 233F 244A 212J 249A 249E 250B 249J 621B 250A 205C 205B 200A 203A 201A 212J 212A 621C 250B 249B 249K 249F EV DOOR PARTS CAUTION Use the part number to order part not the position number 42 https appliancetechmanuals com ...

Page 44: ...S28 602A 600A 600C 622B S29 618A 616E 627A 619C S31 619A 262D 623C EV WATER and ICE MAKER PARTS CAUTION Use the part number to order part not the position number 43 https appliancetechmanuals com ...

Page 45: ...February 2009 MFL49482901 https appliancetechmanuals com ...

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