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7-2-5 TEMPERATURE SENSOR CIRCUIT

The upper CIRCUIT reads FREEZER and REFRIGERATOR temperature, and DEF-SENSOR temperature for defrosting
and the indoor temperature for compensating for the surrounding temperature, into MICOM.
OPENING or SHORT state of each TEMPERATURE SENSOR are as follows.

- 27 -

SENSOR

CHECK POINT

NORMAL(-30 °C ~ 50 °C)

SHORT-CIRCUITED

OPEN

Refrigerator Sensor

POINT Voltage

Defrosting Sensor

POINT Voltage

0.5 V ~ 4.5 V

0 V

5 V

Room Temperature Sensor

POINT Voltage

A

B

C

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Summary of Contents for GR-642APA

Page 1: ...CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL MODEL GR 642APA REFRIGERATOR SERVICE MANUAL http biz lgservice com Ref No GR 642AVPA COLOR SUPER WHITE ...

Page 2: ...unplug prior to servicing 3 In case of testing with power on wear rubber gloves to prevent electric shock 4 If you use any appliances check regular current voltage and capacity 5 Don t touch metal products in cold freezer with wet hand It may cause frostbite 6 Prevent water flowing to electric elements in mechanical parts 7 When you stand up during observing the lower part with the upper door open...

Page 3: ...operation 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...

Page 4: ...pe CONDENSER Wire Condenser REFRIGERANT R 134a 140g DEFROSTING DEVICE HEATER SHELF 1 SPECIFICATIONS 1 1 GR 642 ITEMS SPECIFICATIONS FREEZER 154 NET CAPACITY REFRIGERATOR 399 TOTAL 553 DIMENSIONS mm 860 W X729 D X1794 H NET WEIGHT kg 97 COOLING SYSTEM Fan Cooling TEMPERATURE CONTROL Micom Control Full Automatic DEFROSTING SYSTEM Heater Defrost OUT CASE Pre Coated Metal INNER CASE A B S INSULATION C...

Page 5: ...Utility Corner Freezer Door Rack Leveling Screw Base Cover FREEZER COMPARTMENT Lamp Shelf Deodorizer Vegetable Drawer Used to keep fruits and vegetables etc fresh and crisp Shelves Lamp Fresh Meat REFRIGERATOR COMPARTMENT Freezer Temperature Control Dial Freezer Temperature Control Dial Twisting Ice Serve Option or General Type Ice Making Snack Corner ...

Page 6: ...d is pressed The pad returns to its original position when the glass is removed and the water stops its flow Tab Groove CONNECTING PART WATER TANK LOCK DIAL CAP HANDLE TAB HOLE HOLDER RING BOTTLE HOLDER MOTOR INSIDE DISPENSER GRILLE DRIP TRAY PAD WATER TANK CAUTION 1 Do not use anything other than water including soft drinks milk and juices 2 Hot water needs to be cooled before being put in the wa...

Page 7: ...e the cap 2 Clean the inside and outside of the water tank with dishwashing detergent and rinset horoughly under running water Other Parts Remove the cap and clean the cap and connecting part with a mild detergent and rinse thoroughly CAUTION 1 Use lukewarm water when cleaning 2 Do not use anything other than water If it is used with soft drinks put water in the water tank and discharge three or f...

Page 8: ...WITCH 1 To remove the door switch pull out it with a type driver as shown in figure 9 2 Disconnect the lead wire from the switch 3 3 FAN AND FAN MOTOR 1 Remove the freezer shelf 2 Remove the Cover Lamp F and Case Lamp by loosening 1 screw fixed to ceiling of Inner Case 3 Remove the Grille by pulling it out 4 Pull out the Shroud and remove the Fan Motor Assy by loosening 2 screws 5 Pull out the fan...

Page 9: ...fter inserting finger into the inside hole as shown in figure 16 3 Remove the lamp by turning it counterclockwise 4 Assemble in reverse order of disassembly Replacement bulb must be the same specication as original 3 5 2 Refrigerator room lamp 1 Unplug the power cord from the outlet 2 Remove refrigerator shelves 3 Remove the room lamp lid by taking down while pulling forward with your hands as sho...

Page 10: ...tor 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 resta...

Page 11: ...otects 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 CONTACTIN...

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: ...istone 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 47Ω 30 220 240V 50Hz 47Ω 30 110 115V 60Hz 6 8Ω 30 220V 60Hz 47Ω 30 127V 60Hz 22Ω 30 The resistance value is 0 or several hundreds Ω The value is Check another electric components Replace OLP Check another electric components Replace...

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 Medium Medium Control Low Low Medium High High TEMP C 5 3 2 0 1 ROOM REFRIGERATOR ...

Page 19: ...f and then the all LEDs are kept on 2 While the LED turns on as described above the sensor detects the location of the food and so on 7 1 4 CONTROL OF VARIABLE SPEED FAN IN THE FREEZER COMPARTMENT 1 Fan motor in the freezer compartment shall change from standard to high speed rpm in order to increase cooling speed and load corresponding speed 2 Hign speed rpm is only used for the initial power app...

Page 20: ... defrosting starts the defrosting error code is displayed Refer to 7 1 10 Error Diagnostic Mode 4 With the defective defrosting sensor cut or short circuited wire the defrosting will not be performed 7 1 9 SEQUENTIAL OPERATION OF ELECTRIC COMPONENTS The electric components such as the comp defrosting heater and cooling fan start sequentially to avoid the noise and damage to the part which may resu...

Page 21: ... of the refrigerator while the remaining LEDs are off 21 Error Code Display NO Error Error Code Cause State of Operation with Error Display Comp Cooling fan Defrostingheater 1 2 3 4 Faulty refrigerator R sensor Faulty defrosting sensor Faulty Room temperature sensor in the main PCB Defrosting failure r d when checking LED the error code display all off H Cut or short circuited wire of refrigerator...

Page 22: ...button 1 Continuous operation of the comp once 2 Continuous operation of the freezer fan 3 Defrosting heater OFF 4 Every display LED ON TEST 2 Push the test button 1 Comp OFF Reset if the temp of once while in the 2 Freezer fan OFF the defrosting sensor TEST MODE 1 3 Defrosting heater ON is 10 C or above 4 Every display LED OFF except the refrigerator temp status LEDs Reset Push the test button Re...

Page 23: ...mposed of the CIRCUIT supplying POWER 12Vdc to DISPENSER PUMP MOTOR Voltage of each part is as follows VA1 is a part preventing from over voltage and noise 23 PART Ⓐ PART both ends of VA1 both ends of CE1 both ends of CE2 both ends of CC2 VOLTAGE 220 Vac 17 Vdc 12 Vdc 5 Vdc PART Ⓑ PART both ends of 2nd part both ends of CE6 both ends of CE7 VOLTAGE 13 Vdc 15 Vdc 12 Vdc ...

Page 24: ... 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 25: ...ft open for 7 minutes or longer the lamp of the freezer refrigerator turns off automatically 25 Load Type COMP NO 16 NO 12 NO 10 NO 15 NO 14 NO 13 NO 11 1V or below 12V Defrosting Heater Lamp Freezer Fan Motor Standard RPM Double cooling Fan Motor R FAN R Lamp Freezer Fan Motor HIGH RPM Measurement Location IC5 Condition ON OFF ...

Page 26: ...the button on the display is pushed Alarm for open door beep beep beep OFF IC1 0 V IC1 0 V Measure ment Location Condition 0 V 5 V 0 V 5 V 0 5 s 0 5 s 1 9kHz Beep OFF 0 1 s 0 5 s 0 V 5 V 0 V 5 V 1 9 kHz Beep PIN NO 15 Closed 0 V Open 5 V Freezer Refrigerat Door Measurement Location A B ...

Page 27: ...nd the indoor temperature for compensating for the surrounding temperature into MICOM OPENING or SHORT state of each TEMPERATURE SENSOR are as follows 27 SENSOR CHECK POINT NORMAL 30 C 50 C SHORT CIRCUITED OPEN Refrigerator Sensor POINT Voltage Defrosting Sensor POINT Voltage 0 5 V 4 5 V 0 V 5 V RoomTemperatureSensor POINT Voltage A B C ...

Page 28: ...ircuits for less cooling and overcooling compensation in a refrigerator compartment The above OPTION circuit is to compensate refrigerator temperature by simply cutting during service 28 CUT OVER COOLING LESS COOLING COMPENSATION COMPENSATION REFRIGERATOR TEMPERATURE REMARKS JCR1 JCR2 JCR3 JCR4 COMPENSATION VALUES CUT 1 C CUT CUT 2 C CUT 1 C CUT CUT 2 C CUT CUT 0 C CUT CUT 0 C CUT CUT CUT 1 C CUT ...

Page 29: ...LAY 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 LED Module The drive type is the scan type 29 ...

Page 30: ...verse rotate for 0 5 second 30 A FORWARD A REVERSE STOP ROTATE STOP ROTATE STOP PUMP S W OPERATION PUMP MOTOR OPERATION PUMP S W PART both ends of CC11 H L H H H NO 11 of IC1 H H H L H PUMP MOTOR NO 12 of IC1 H L H H H PART VOLTAGE CHECK as MULTIMETER 0V 12V 0V 12V 0V connect Ⓐ Ⓑ 0 6 sec 0 5 sec RELEASE PRESS A FORWARD ROTATE STOP A REVERSE ROTATE CHECK POINT MOTOR OPERATION STATE ...

Page 31: ...speed Measure the F SENSOR SUPER FROST SENSOR R1 R2 SENSOR after disconnect CON5 of PWB ASSY MAIN TEMPERATURE SENSOR RESISTANCE OF FREEZER RESISTANCE OF REFRIGERATOR SENSOR DEFROST SENSOR 20 C 22 3 KΩ 77 KΩ 15 C 16 9 KΩ 60 KΩ 10 C 13 0 KΩ 47 3 KΩ 5 C 10 1 KΩ 38 4 KΩ 0 C 7 8 KΩ 30 KΩ 5 C 6 2 KΩ 24 1 KΩ 10 C 4 9 KΩ 19 5 KΩ 15 C 3 9 KΩ 15 9 KΩ 20 C 3 1 KΩ 13 KΩ 25 C 2 5 KΩ 11 KΩ 30 C 2 0 KΩ 8 9 KΩ 40...

Page 32: ...locked If pass less than 7 minutes OLP PTC is poor Replace OLP PTC after stop of COMP don t COMPRESSOR RELAY is Replace MAIN PWB RY1 press it and stand by poor THE CONNECTING WIRE Certify the black wire of MAIN is poor PWB CONNECTOR CON2 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 Refrigera...

Page 33: ... is NO DEFROSTING 1 HEATER emit heat PRESS TEST KEY on MAIN HEATER disconnection Replace HEATER poor on MAIN PWB three times forced DEFROSTING TEMPERATURE FUSE Replace TEMPERATURE disconnection FUSE Connection is poor Certify EVA connection and wire of MAIN PWB CONNECTOR DEF SENSOR is poor Replace DEF SENSOR HEATER RELAY is poor Replace RY5 of MAIN PWB 2 DRAIN PIPE blocking Certify DRAIN PIPE DRAI...

Page 34: ...7 5 MAIN PWB ASS Y AND PARTS LIST 7 5 1 MAIN PWB ASS Y 34 ...

Page 35: ...7 5 2 REPLACEMENT PARTS LIST 35 ...

Page 36: ...7 5 3 PWB ASS Y DISPLAY AND PARTS LIST 36 ...

Page 37: ...7 6 PWB DIAGRAM 37 ...

Page 38: ... 38 ...

Page 39: ... 8 EXPLODED VIEW REPLACEMENT PARTS LIST 39 324A 106A 304A 406B 104A 106A 315A 283B 105A 282B 282A 103C 281B 501F 323B 328A 329C 420A 319A 315B 315B 315C 318A 314A 307A 312A 317A 310A 120A 327A 129A 158A 158B 409A 281A 604G 319C 604E 501A 501K 501B C 410G 411A 328B 401A 309A 308A 282J 158C 103B 103A 158F 329D 410J 409B 409C 301A 418A 407A EV ...

Page 40: ...A 149C 149C 140B 140A 149B 205A 205A 241A 241D 241A 233A 230A 203A 200A 210A 210B 241B 231A 201A 235A 131A 131C 243A 243B 212G 244A 244C 212C 212A 503B 503C 125A 125H 149A 149A 330B 405C 404A 329A 405A 332A 125A 131A 151A EV ...

Page 41: ...49C 140B 140A 125A 125H 149A 131A 125A 149A 205A 330B 405C 404A 329A 405A 205A 241D 241A 233A 230A 203A 200A 210A 210B 231A 201A 332A 235A 131A 131C 131C 243A 243B 212G 503B 503C 241A 241B 212B 212A 212C 244C 244A 244B 212D 244D 149B EV ...

Page 42: ...C 140B 140A 125A 125H 149A 131A 125A 149A 205A 330B 405C 404A 329A 405A 205A 241D 241A 233A 230A 203A 200A 210A 210B 231A 201A 332A 235A 131A 131C 131C 243A 243B 212G 503B 503C 241A 241B 149B 212A 244A 151A 1SZZJA 109A 1SZZJA 109A EV ...

Page 43: ... 43 611P 611M 611Q 611A 611B 611C 611D 611H 611S 611T 611N 611R 611Y 611Z 611E 611K 611W 611X EV ...

Page 44: ...P No 3828JD8734B OCT 2004 Printed in Korea ...

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