LG GR-391SCA Service Manual Download Page 21 | Manualshive

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7-2 PCB FUNCTION

7-2-1 POWER CIRCUIT

The secondary part of the TRANS is composed of the power supply for the display and relay drive (12Vdc) and that for the
MICOM and IC (5Vdc).

The voltage for each part is as follows.

VA1 is a part for preventing the over voltage and noise. When 385V or higher power is applied, the inside elements are
short-circuited and broken, resulting in the blowout of the fuse in order to protect the elements of the secondary part of the
TRANS.

- 21 -

PART

VA 1

CE 2

CE3

VOLTAGE

220 Vac

12 Vdc

5 Vdc

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Summary of Contents for GR-391SCA

Page 1: ...CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL MODEL GR 391SCA REFRIGERATOR SERVICE MANUAL Ref No GR 432SCA GR 431SCA GR 482SCA COLOR SUPER WHITE http biz lgservice com ...

Page 2: ...ecially thin plate type ex glass shelf or books 9 When servicing evaporator part wear cotton gloves without fail It is to prevent wound by sharp fin of evaporator 10 Leave a breakage of refrigerating cycle to a heavy service center The gas in cycle inside may soil ambient air SAFETY PRECAUTIONS CONTENTS 2 SAFETY PRECAUTIONS 2 SERVICING PRECAUTIONS 3 SPECIFICATIONS 4 PARTS IDENTIFICATION 5 DISASSEM...

Page 3: ...ration is over add the quantity in grams of R 134a to the refrigerant system Remember that every system has an exact quantity of R 134a with a tolerance of 5 grams that can be added Figure 4 Before performing this operation if the vacuum pump and refilling cylinder are connected make sure that the valve placed between the vacuum pump and refilling tube are closed to keep the Freon for adding to th...

Page 4: ...nob Dial REFRIGERATOR Micom Control Full Automatic Heater Defrost OUT CASE Coated Steel Sheet INNER CASE A B S INSULATION Polyurethane Foam FREEZER 1 EA REFRIGERATOR 2 EA VEGETABLE TRAY Drawer Type EGG TRAY 2 Pieces ICE TRAY 1 Piece 2 ICE BANK 1 Piece COMPRESSOR P T C Starting Type EVAPORATOR Fin Tube Type CONDENSER Wire Condenser REFRIGERANT R134a 150g DEFROSTING DEVICE L CORD TE PLATE HEATER l S...

Page 5: ...sting Ice Serve or General Type Ice Making Freezer Shelf Plastic or Steel REFRIGERATOR COMPARTMENT Deodorizer Option Chilled Room Refrigerator Temperauer Electronic Control Lamp F I R Lamp Option Shelves Plastic or Steel Multi Flow Duct Distributes cold air to each part of refrigerator compartment Vegetable Drawer Used to keep fruits and vegetables etc fresh and crisp Dairy Corner Movable Rack Veg...

Page 6: ...from the switch 3 3 THERMOSTAT 1 Remove the Cover Lamp R by the use of type driver inserting in the low holes of the cover 2 Loose 2 screw 3 Pull the Control Box R 4 Disconnect the Housing of lead wire 5 Separate the INSU Multi Duct and Control Box R 6 Separate the Thermistor and Control Box R 7 Separate the Thermistor and Display PCB 3 4 FAN AND FAN MOTOR 1 Remove the freezer shelf 2 Separate the...

Page 7: ... 1 Pull out the Shroud after removing the Grille 2 Separate the connector connected with the Def Control Assy and replace the Def Control Assy after cutting the Tie Wrap and removing the Holder Fuse Figure 14 3 6 LAMP 3 6 1 Freezer room lamp 1 Pull forward the lamp cover F hole 2 Remove the lamp F by turning 3 6 2 Refrigerator room lamp 1 Remove the cover lamp R by pulling with a type driver 2 Rem...

Page 8: ...m Don t lay the refrigerator down in working with it it will cause to get out of order 4 Be careful not to drop the door in disassembling or assembling the freezer or the refrigerator door 5 This refrigerator according to the install position or user s liking can be used as the type of opening from the right or the left W HOW TO REPLACE THE DOOR OPENING TYPE WHEN CONVERTING FROM THE LEFT OPENING T...

Page 9: ... of the Refrigerator Door 8 Move the Cap J and Assemble the Hinge C D After removing the washer 9 8 4 10 9 Assembe the Door Stopper F K for Right Opening Type 10Move the Cap L and Assemble the Freezer Door C 11 3 3 12 5 11Move the Pin Position M of the Hinge Upper 12Assemble the Hinge Upper B and the Cap A 13 2 1 ...

Page 10: ...For normal operation of single phase induction motor in the starting operation flows in both main coil and sub coil After the starting is over the current is cut off in subcoil The proper features of PTC play the above all roles So PTC is used as a starting device of motor 4 2 3 PTC Applied Circuit Diagram According to Starting Method of Motor 4 2 4 Motor Restarting and PTC Cooling 1 For restartin...

Page 11: ...ts Motor by cutting off current which flows to Compressor Motor 4 3 2 Role of OLP 1 OLP is attached to Hermetic Compressor used to Refrigerator and Show Case and prevents Motor Coil from being started in the Compressor 2 Do not turn the Adjust Screw of OLP in any way for normal operation of OLP Composition and connection Diagram of OLP 5 CIRCUIT DIAGRAM CONTACTING POINT COVER BIMETAL CONTACTING PO...

Page 12: ...dvise the customer to use a regular Trans Replace Compressor OLP works within 30 sec in forcible OLP operation by turning instant power on and off Components start in the voltage of Rating Voltage 10 below Applied voltage isn t in the range of Rating Voltage 10 Check the resistance among M C S C and M S in Motor Compressor Check the resistance of two terminals in PTC Starter Check if applying a re...

Page 13: ... Tester or Whistone Bridge Figure 22 Separate the OLP from Compressor and check resistance value between two terminals of OLP with a Tester Figure 23 Observation value is 220V 50Hz 22 30 115V 60Hz 6 8 30 240V 50Hz 33 30 127 220V 60Hz 22 30 The resistance value is 0 or several hundreds The value is Check another electric components Replace OLP Check another electric components Replace PTC Figure 23...

Page 14: ...ressor Replace the compressor Replace each component Raise the voltage Replace each component Cause Check if current flows to starting devices Check current flowing in sub coil of Compressor Check capacity of OLP The items described above are normal Cooling ability is poor Fan motor doesn t run Much frost are sticked to the EVAPORATOR Poor contacting Coil is shorted Shorted Replace each component ...

Page 15: ...ten or check if the door is closed up it firmly Dew forms Check if ambient temperature and humidity Wipe dew with a dry cloth This happening in the Out Case of surroumcling air are high is solved in low temperature and humidity naturally Is the gap in the door packed Fill up the gap Abnormal Is the set positioned in a firm and even place Adjust the Adjust Screw and position noise generates in the ...

Page 16: ...re Normal cooling is possible don t get cold formed when injecting Refrigerant at all of regular amount PARTIAL Freeze room and Flowing sound of Refrigerant A little high Normal discharging of CLOG Refrigerator is heard and frost forms more than refrigerant don t get cold in inlet only ambient The capillary tube is faulty normally temperature WHOLE Freezer and Flowing sound of Refrigerant Equal to...

Page 17: ...ge without fail 1 gauge of charging M C vacuum Perform vacuum operation until a proper 1 degree is within 1 Torr vacuum degree is built up 2 If the vacuum degree of the cycle inside is If a proper vacuum degree isn t built up 2 10 Torr below for low pressure and 20 Torr check the leakage from 2 for high pressure it says no vacuum the Cycle Pipe line part and 2 leakage state Quick Coupler Connectin...

Page 18: ...ce is plugged in it is set to Medium Each time the button is pushed it is set to Medium Medium High High Low Medium Low Medium in order 2 When the power is initially applied or restored after a power failure it is automatically set to Medium 7 DESCRIPTION OF FUNCTION CIRCUIT OF MICOM 18 Temp Control Medium Medium Low Low Medium High High TEMP C 7 4 2 0 2 ROOM REFRIGERATOR ...

Page 19: ...sting heater and cooling fan start sequentially to avoid the noise and damage to the part which may result from the simultaneous start of various components on turning the power on or after the completion of a test 7 1 4 CONTROL OF DOUBLE COOLING FAN IN THE REFRIGERATOR COMPARTMENT 1 To raise the refrigerating speed Fan Motor in the Refrigerator Compartment is operated when the door of freezer roo...

Page 20: ...isplayed by the refrigerator temp indication LED on the display of the refrigerator while the remaining LEDs are off 20 R4 R3 R1 R2 NO Error Error Code Display Cause State of Operation with Error R1 R2 R3 R4 Comp Cooling fan Defrostingheater ON OFF 1 2 3 Faulty refrigerator R sensor on the control box of the refrigerator Faultydefrostingsensor Defrosting failure Cut or short circuited wire of refr...

Page 21: ...MICOM and IC 5Vdc The voltage for each part is as follows VA1 is a part for preventing the over voltage and noise When 385V or higher power is applied the inside elements are short circuited and broken resulting in the blowout of the fuse in order to protect the elements of the secondary part of the TRANS 21 PART VA 1 CE 2 CE3 VOLTAGE 220 Vac 12 Vdc 5 Vdc ...

Page 22: ... is changed 7 2 3 RESET CIRCUIT The RESET circuit is for allowing 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 n...

Page 23: ...7 2 4 LOAD DRIVE CIRCUIT 1 Load Drive Condition Check 23 Load Type Defrosting Heater Refrigerator Fan Measurement Location IC5 No 13 No 10 No 12 ON 1V or below Condition OFF 12V Comp Freezer Fan Motor ...

Page 24: ...MICOM OPENING or SHORT state of each TEMPERATURE SENSOR are as follows 7 2 6 DOOR OPEN DETECTING CIRCUITS 24 SENSOR CHECK POINT NORMAL 30 C 50 C SHORT CIRCUITED OPEN Refrigerator Sensor POINT Voltage 0 5 V 4 5 V 0 V 5 V Defrosting Sensor POINT Voltage A B MEASURING POINTS Freezer Refrigerator Door CLOSED OPEN IC1 Pin No 8 5 V 0 V ...

Page 25: ... compensation resistance RCR1 is changed from 10K the current resistance to 18K the adjustment resistance the temperature of the refrigerator rises 1 C Refrigerator Resistance Temperature Remark RCR1 Compensation 180 KΩ 2 5 C Compensation by 56 KΩ 2 0 C raising the 33 KΩ 1 5 C temperature 18 KΩ 1 0 C 12 KΩ 0 5 C 10 KΩ 0 C Standard Temperature 8 2 KΩ 0 5 C Compensation by 5 6 KΩ 1 0 C lowering the ...

Page 26: ... DISPLAY LIGHT ON CIRCUIT The circuit shown above is to determine whether a function control key on the operation display is pushed and to turn on the corresponding function indication LED The drive type is the scan type 26 ...

Page 27: ...emperature This postponing is necessary because of perceiving speed Measure the F SENSOR SUPER FROST SENSOR R1 R2 SENSOR after disconnect CON5 of PWB ASSY MAIN TEMPERATURE SENSOR RESISTANCE OF REFRIGERATOR DEFROST SENSOR 20 C 77 KΩ 15 C 60 KΩ 10 C 47 3 KΩ 5 C 38 4 KΩ 0 C 30 KΩ 5 C 24 1 KΩ 10 C 19 5 KΩ 15 C 15 9 KΩ 20 C 13 KΩ 25 C 11 KΩ 30 C 8 9 KΩ 40 C 6 2 KΩ 50 C 4 3 KΩ ...

Page 28: ...OMPRESSOR lock or Replace COMPRESSOR blocked OLP PTC is poor Replace OLP PTC COMPRESSOR RELAY is Replace MAIN PWB RY1 poor THE CONNECTING WIRE Certify the black wire of MAIN is poor PWB CONNECTOR CON1 2 Whether refrigerant leaks or Measure the amount of frost Refrigerant leakage Remedy the leaking part leaks or not sticking on EVA and the and reaching Refrigerant surface temperature of condenser p...

Page 29: ...G is poor DEFROSTING is NO DEFROSTING 1 HEATER emit heat Check the MAIN PCB HEATER disconnection Replace HEATER poor TEMPERATURE FUSE Replace TEMPERATURE disconnection FUSE Connection is poor Certify EVA connection and wire of MAIN PWB CONNECTOR CON1 DEF SENSOR is poor Replace DEF SENSOR HEATER RELAY is poor Replace RY4 of MAIN PWB 2 DRAIN PIPE blocking Certify DRAIN PIPE DRAIN PIPE blocking Remov...

Page 30: ...7 5 MAIN PWB ASSEMBLY AND PARTS LIST 7 5 1 MAIN PWB ASSEMBLY 30 ...

Page 31: ...7 5 2 REPLACEMENT PARTS LIST 31 ...

Page 32: ...7 5 3 PWB ASSEMBLY DISPLAY AND PARTS LIST 32 ...

Page 33: ...7 6 PWB DIAGRAM 33 ...

Page 34: ... 34 REF TEMP CONTROL ...

Page 35: ...301A 418A 120A 409B 409C 158C 106B 158F 158A 410J 315C 104C 407A 282J 410G 410H 35 8 EXPLODED VIEW The parts of refrigerator and the shape of each part are subject to change in different localities Capacitors and fuse are optional parts Optional parts 1 Freezer Shelf Plastic 149A Steel 136 136D 2 Ice Maker Twist 110B 125A 125H 131A Standard 125J 3 Refrigerator Shelves Plastic 149C Steel 136A 136B ...

Page 36: ... 36 154A 149C 151A 149C 155B 330B 405A 405C 404A 149C 140A 149B 332A 149D 136D 149C 136A 136B 136A 136B 149A 110B 125A 131A 136C 125J 125H 329A 330B EV ...

Page 37: ...241C 205A 205A 241A 233A 203A 235A 200A 230A 233B 210A 231A 201A 244A 244C 212C 212A 212G 233B 231A 231A 201A 201A 210A 212G 212A 212C 210A 244A 244C 212G 212A 244A 1SZZJA 109A 1SZZJA 109A 233B 234B 210A 243A 210A 243A EV ...

Page 38: ...P NO 3828JD8746B APR 2005Printed in Korea ...

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