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LG GR-B492Y*C, Service Manual

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LG GR-B492Y*C Service Manual Download Page 24

7-2 PCB FUNCTION

7-2-1 POWER CIRCUIT

The power circuit consists of the noise attenuation part and the SMPS (Switch Mode Power Supply) part. The SMPS
consists of the rectifier (D1,D2,D3,D4 & CE1) to convert AC voltage to DC voltage, switching part (IC2) to switch the
converted DC voltage, transformer to transmit energy of the first side of the switching end to the second side, the secondary
power to supply power to MICOM and IC, and the feedback part (IC3) to feedback the secondary voltage to the first side of
the transformer in order to maintain the secondary voltage constant.

Caution: 

High voltage (DC 310V) is maintained in this circuit. Wait at least 3 minutes after unplugging to allow the

current to dissipate. There is a danger of electric shock.

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Summary of Contents for GR-B492Y*C

Page 1: ...CAUTION BEFORE SERVICING THE UNIT READ THE SAFETY PRECAUTIONS IN THIS MANUAL MODEL GR M492Y Y GR B492Y Y GR B492Y Q GR B492Y C REFRIGERATOR SERVICE MANUAL http biz lgservice com ...

Page 2: ...lectric shock 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 u...

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: ... Micom Control DEFROSTING SYSTEM Full Automatic Heater Defrost OUT CASE Pre Coated Metal INNER CASE A B S INSULATION Cyclo Pentane Foam FREEZER 1 EA REFRIGERATOR 2 EA 3EA Option VEGETABLE TRAY Drawer Type EGG TRAY 1 Piece ICE TRAY 2 Piece ICE BANK 1 Piece COMPRESSOR P T C Starting Type EVAPORATOR Fin Tube Type CONDENSER Wire Condenser REFRIGERANT R 134a 125g DEFROSTING DEVICE Heater l TEMPERATURE ...

Page 5: ...eatures shown above FREEZER COMPARTMENT REFRIGERATOR COMPARTMENT Lamp In Door Ice Maker Optional Twisting Ice Serve Optional or Freezer Door Rack Egg Storage Rack Green Ion Door Cooling Optional Dairy Corner Levelling Screw Refrigerator Door Rack Lamp Base Cover Shelves Fresh Zone Vegetable Drawer helf Vitamin Kit Optional Freezer Temperature Control Dial Deodorizer Optional oner Optional ...

Page 6: ...purchased may have some or all of the features shown above FREEZER COMPARTMENT REFRIGERATOR COMPARTMENT Lamp Freezer Temperature Control Dial Freezer Door Rack Levelling Screw Refrigerator Door Rack Lamp Base Cover Shelves Fresh Zone Vegetable Drawer Shelf Twisting Ice Serve Deodorizer Optional ...

Page 7: ...CH 1 T o remove the door switch pull out it with a Ñ type Ass y 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 by loosening 1 screw fixed to ceiling of Inner Liner 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 and se...

Page 8: ...Wrap Figure 14 3 5 LAMP 1 Unplug the power cord from the outlet 2 Remove the room lamp lid by loosening 1screw and take down while pulling it forward with both hands as shown in figure 3 Remove the lamp by turning it counterclockwise 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 pulling it forward 4 Make sure the bu...

Page 9: ... 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 l According to Starting Method of Motor 4 2 4 Motor Restarting and PTC Cooling 1 For restar...

Page 10: ...s by heating the heater inside OLP and OLP protects 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 10 CONTACTING...

Page 11: ...u u u GR M492Y Y GR B492Y Y GR B492Y Q u u u GR B492Y C NOTE 1 This is a basic diagram and specifications vary in different localities 5 CIRCUIT DIAGRAM 11 ...

Page 12: ...cted Advise 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 at voltage 10 of rated voltage 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 regular...

Page 13: ...Wheat stone bridge Figure 22 Separate the OLP from Compressor and check resistance value between two terminals of OLP with a T ester Figure 23 Observation value at 220V 50Hz 47 30 220 240V 50Hz 47 30 110 115V 60Hz 6 8 30 220V 60Hz 47 30 127V 60Hz 22 30 The resistance value is 0 or several hundreds or infinity Check another electric components Replace OLP Check another electric components Replace P...

Page 14: ... 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 t 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 Repl...

Page 15: ...n 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 surrounding 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 Leveling screw and position noise generates in the f...

Page 16: ...re Normal cooling is possible don t get cold formed when injecting Refrigerant at all of regular amount PARTIAL Freezer room and Flowing sound of Refrigerant A little higher Normal discharging of CLOG Refrigerator is heard and frost forms 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 a...

Page 17: ...ithout fail 1 gauge of charging M C vacuum Perform vacuum operation until a proper 1 degree is within 1 T orr 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 T orr below for low pressure and 20 T orr check the leakage from 2 for high pressure it says no vacuum the Cycle Pipe line part and 2 leakage state Quick Coupler Connecting...

Page 18: ... ÕÕ4Õ in order and Interior display is set to ÔR2Õ ÕÕR3Õ ÕÕR4Õ ÕÕR0Õ ÕÕR1Õ 2 When the power is initially applied or restored after a power failure it is automatically set to Ô3Õ against the interruption of electric power 7 DESCRIPTION OF FUNCTION CIRCUIT OF MICOM 18 u GR M492Y Y GR B492Y Y GR B492Y Q u GR B492Y C MIN MAX REF TEMP CONTROL Temp Medium Medium Control Low Low Medium High High TEMP ßC ...

Page 19: ... RPM 7 1 3 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 application super cool mode and load corresponding operation But standard rpm is used in the general working conditions 3 When the d...

Page 20: ... circuited wire the defrosting will not be performed 7 1 7 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 result from the simultaneous start of various components on turning the power on or after the completion of a test Condition of Operation Operating Seq...

Page 21: ...92Y Y GR B492Y Y GR B492Y C NO Error Error Code Cause State of Operation with Error Display Comp Cooling fan Defrosting heater 1 2 3 4 Faulty refrigerator R sensor Faulty defrosting sensor Faulty Room temperature sensor in the main PCB Defrosting failure r d when super cool and refrigerator key pressed together display will be all off Cut or short circuited wire of H refrigerator sensor Cut or sho...

Page 22: ...are off 22 u GR B652Y C MIN MAX REF TEMP CONTROL NO Error Error Code Display Cause R0 R1 R2 R3 R4 Comp Cooling fan Defrosting heater OFF ON 1 2 3 4 Faulty refrigerator sensor on the control box of the refrigerator Faulty defrosting sensor Faulty room temp sensor in the main PCB Defrosting failure Cut or short circuited wire of refrigerator sensor Cut or short circuited wire of defrosting sensor Cu...

Page 23: ...test button 1 Continuous operation of the comp once 2 Continuous operation of the freezer fan 3 Defrosting heater OFF 4 Every display LED ON 5 F lamp can be switch on off by door open close 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 13 C or above 4 Every display LED OFF except the refri...

Page 24: ... voltage transformer to transmit energy of the first side of the switching end to the second side the secondary power to supply power to MICOM and IC and the feedback part IC3 to feedback the secondary voltage to the first side of the transformer in order to maintain the secondary voltage constant Caution High voltage DC 310V is maintained in this circuit Wait at least 3 minutes after unplugging t...

Page 25: ... 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 includingthe 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 ÔLOWÕ voltage is applied to the MICOM RESET terminal During a ...

Page 26: ...he door of the freezer refrigerator is left open for 7 minutes or longer the lamp of the freezer refrigerator turns of f automatically 26 Load Type COMP NO 16 NO 12 NO 12 NO 14 NO 11 1V or below 12V Defrosting Heater Lamp R Lamp Fan Motor Low RPM Measurement Location IC6 Condition ON OFF ...

Page 27: ...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 9 kHz Beep OFF 0 1 s 0 5 s 0 V 5 V 0 V 5 V 1 9 kHz Beep PIN NO 34 Closed 0 V Open 5 V Freezer Measurement Refrigerat Door Location A B ...

Page 28: ...is shown below 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 28 SENSOR CHECK POINT NORMAL 30 C 50 C SHORT CIRCUITED OPEN Room Temperature Sensor POINT Voltage Refrigeration Sensor POINT Volta...

Page 29: ... circuits for less cooling and overcooling compensation in a refrigerator compartment The above OPTION circuit is to compensate refrigerator temperature by simply cutting during service 29 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 CU...

Page 30: ...AY LIGHT ON CIRCUIT ç 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 30 ...

Page 31: ...iving 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 ßC 22 3 K 77 K 15 ßC 16 9 K 60 K 10 ßC 13 0 K 47 3 K 5 ßC 10 1 K 38 4 K 0 ßC 7 8 K 30 K 5 ßC 6 2 K 24 1 K 10 ßC 4 9 K 19 5 K 15 ßC 3 9 K 15 9 K 20 ßC 3 1 K 13 K 25 ßC 2 5 K 11 K 30 ßC 2 0 K 8 9 K 40 ßC 1...

Page 32: ...d COOLING blocked 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 not sticking on EVA and the and reaching Refrige...

Page 33: ...NG is NO DEFROSTING 1 HEATER emit heat PRESS TEST KEY on MAIN HEATER disconnection Replace HEATER poor 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 DRAIN PIPE...

Page 34: ...7 5 MAIN PWB ASS Y AND PARTS LIST 7 5 1 MAIN PWB ASS Y In the case of GR M652 M712 203V model P No of main ASSÕY is used as EBR327903 34 ...

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

Page 36: ... 36 ...

Page 37: ...7 5 3 PWB ASS Y DISPLAY AND PARTS LIST 37 ...

Page 38: ... 38 7 5 4 PWB ASS Y DISPLAY I MICOM AND PARTS LIST ...

Page 39: ... 39 7 5 5 V LED DISPLAY PART LIST ...

Page 40: ...7 6 PWB DIAGRAM 40 ...

Page 41: ... 41 ...

Page 42: ...b e t to ch ge n i ferent loca it es c ors d s p i p s Capa it an fu e are o t onal art 8 EXPLODED VIEW REPLACEMENT PAR S LIST T 42 501F 103 166 165 411A 158 501K 171 129A 115 109 164 121 604G 109 142 145 181 323B 183 312A 29 150 148 179 40 318A 105A 418A 116 108 139 329A 178 106A 182 120A ...

Page 43: ... 43 111 138 154A 140A 120 110 134 149B 118 119 405C 404A 405C 405A 329B 155J ...

Page 44: ... 44 241D 244C 244A 241A 235A 173 241C 205A 205A 279A 162 212A 212C 101 102 122 123 241E 172 ...

Page 45: ...P No MFL38971701 MAR 2007 Printed in Korea ...

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