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LG MS-191MC Service Manual

Microwave oven
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MICROWAVE OVEN

SERVICE MANUAL
MODEL : MS-191MC
CAUTION
BEFORE SERVICING THE UNIT, READ THE
SAFETY PRECAUTIONS IN THIS MANUAL.

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Summary of Contents for LG MS-191MC

  • Page 1: Microwave Oven

    MICROWAVE OVEN SERVICE MANUAL MODEL : MS-191MC CAUTION BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

  • Page 2: Service Information

    SERVICE INFORMATION TOOLS AND MEASURING INSTRUMENTS NECESSARY TOOLS NECESSARY MEASURING INSTRUMENTS Tools normally used for TV servicing are sufficient. ¥ TESTER(VOLTS-DC, AC., Ohmmeter) Standard tools are listed below. ¥ Microwave survey meter ¥ Diagonal pliers - Holaday HI-1500 ¥ Long nose pliers HI-1501 ¥...

  • Page 3: Measurement With Outer Case Removed

    MEASUREMENT WITH OUTER CASE NOTES WHEN MEASURING REMOVED ¥ Do not exceed meter full scale deflection. ¥ The test probe must be removed no faster than ¥ When you replace the magnetron, measure for 1 inch/sec (2.5 cm/sec) along the shaded area, microwave energy leakage before the outer case is otherwise a false reading may result.

  • Page 4: Measurement Of Microwave Power Output

    MEASUREMENT OF MICROWAVE POWER OUTPUT ¥ Microwave power output measurement is made with ¥ The microwave power output P in watts is calculated the microwave oven supplied at its rated voltage and from the following formula : operated at its maximum microwave power setting with 4187 x (ÆT) a load of (1000±5) g of potable water.

  • Page 5: Fan Motor Assembly Removal

    D. DOOR GROSS ASSEMBLY REMOVAL E. HIGH VOLTAGE TRANSFORMER 1) Open the door. REMOVAL 2) Remove the choke cover very carefully with a flat- 1) Discharge the high voltage capacitor. blade screwdriver. 2) Disconnect the leadwire from magnetron, high voltage CAUTION : Be careful not to damage door seal plate transformer, and capacitor.

  • Page 6: Magnetron Removal

    H. AIR DUCT ASSEMBLY REMOVAL J. REMOVING THE TURNTABLE MOTOR 1) Remove the turntable. 1) Disconnect the leadwire from the lamp. 2) Remove the turntable shaft VERY CAREFULLY. 2) Remove the mounting screw to the latch board. 3) Lay the unit down on its back. 4) Remove the turntable motor cover.

  • Page 7: Pcb Assembly Removal

    K. PCB ASSEMBLY REMOVAL L. INTERLOCK SYSTEM 1) Remove the control panel assembly from the 1) INTERLOCK MECHANISM cavity. (Refer to control panel assembly removal The door lock mechanism is a device which has on previous page.) been specially designed to eliminate completely 2) Remove screws which hold the PCB SUB ASSÕY to microwave activity when the door is opened during the control panel.

  • Page 8: Interlock Continuity Test

    INTERLOCK CONTINUITY TEST WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS. TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR PRIMARY SWITCH TYPE NO. SZM-V 16-FA-62 OR VP-532A-OF FOR MONITOR SWITCH TYPE NO. SZM-V 16-FA-63 OR VP-533A-OF FOR SECONDARY SWITCH B.

  • Page 9: Component Test Procedure

    COMPONENT TEST PROCEDURE CAUTIONS 1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUTER CASE FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR AND REMOVING THE WIRE LEADS FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER.

  • Page 10: High Voltage Capacitor

    COMPONENTS TEST PROCEDURE RESULTS Antenna Gasket Chassis Filament Terminals NOTE: When testing the magnetron, be sure to install the magnetron gasket in the correct position and be sure that the gasket is in good condition. HIGH VOLTAGE Measure the resistance. Normal: Momentarily indicates CAPACITOR (Ohm-meter scale: Rx1000)
  • Page 11 COMPONENTS TEST PROCEDURE RESULTS Check for continuity of relay 2 with an RELAY 2 POWER ohm-meter. LEVEL (Remove wire leads from relay 2 and operate the unit.) 6 sec 16 sec 10 sec 12 sec Relay 1 14 sec 8 sec Relay 2 18 sec 4 sec...

  • Page 12: Troubleshooting

    TROUBLE SHOOTING WHEN YOU GET A COMPLAINT FROM YOUR CUSTOMER, EVALUATE THE COMPLAINT CAREFULLY. IF THE FOLLOWING SYMPTOMS APPLY, PLEASE INSTRUCT THE CUSTOMER IN THE PROPER USE OF THE MICROWAVE OVEN. THIS CAN ELIMINATE AN UNNECESSARY SERVICE CALL. CAUTIONS 1. Check grounding before checking for trouble. 2.
  • Page 13 (TROUBLE 1) The following visual conditions indicate a probable defective control circuit. 1. Incomplete segments. ¥ Segment missing. ¥ Partial segment missing. ¥ Digit flickering (NOTE:Slight flickering is normal.) 2. Colon does not turn on or blink. 3. A distinct change in the brightness of one or more numbers in display. 4.
  • Page 14 (TROUBLE 2) Oven does not operate at all; Display window does not display any figures, and no input is accepted. CONDITION CHECK RESULT CAUSE REMEDY Malfunction of the Replace fuse, Check continuity 1. Fuse blows. Continuity. monitor switch. primary, monitor of monitor switches, and switch (with...
  • Page 15 (TROUBLE 3) Display shows all figures set, but oven does not start cooking while desired program times are set and START pad is touched. CONDITION CHECK RESULT CAUSE REMEDY Defective Replace Check continuity 1. Setting time No continuity. secondary switch. secondary switch.
  • Page 16 (TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run. (Display operates properly) CONDITION CHECK RESULT CAUSE REMEDY No microwave Defective PCB Replace PCB Disconnect the No continuity. oscillation. assembly. assembly. wire leads from relay 2 and check continuity Continuity.
  • Page 17 (TROUBLE 5) No microwave oscillation even though oven lamp and fan motor run. (Display operates properly) CONDITION CHECK RESULT CAUSE REMEDY Defective PCB Replace PCB Output is full power Disconnect the Abnormal. assembly. assembly. when you set lower wire leads from power level.

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