MICROWAVE OVEN M1912 SERVICE MICROWAVE OVEN Manual CONTENTS 1. Precaution 2. Specifications 3. Operating Instructions 4. Disassembly and Reassembly 5. Alignment and Adjustments 6. Troubleshooting 7. Exploded Views and Parts List 8.
1. Precaution Follow these special safety precautions. Although the microwave oven is completely safe during ordinary use, repair work can be extremely hazardous due to possible exposure to microwave radiation, as well as potentially lethal high voltages and currents. 1-1 Safety precautions ( ) 1. All repairs should be done in accordance with the procedures described in this manual. This product complies with Federal Performance Standard 21 CFR Subchapter J (DHHS). 2.
Pretaution 1-2 Special Servicing Precautions (Continued) 17. When checking the continuity of the witches or transformer, always make sure that the power is OFF, and one of the lead wires is disconnected. 18. Components that are critical for safety are indicated in the circuit diagram by shading, or . 19. Use replacement components that have the same ratings, especially for flame resistance and dielectric strength specifications.
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Operating Instruction 3-2 Features & External Views VENTILATION HOLES LIGHT VARIABLE COOKING POWER CONTROL KNOB TIMER KNOB DOOR LATCHES ROLLER RING TURNTABLE COUPLER SAFETY INTERLOCK HOLES 297mm DOOR OPEN DOOR PUSH BUTTON 336mm 517mm 241mm 379mm 3-3 Checking That Your Oven is Operating Correctly NOTE: The oven must be plugged into an appropriate wall socket. The glass plate must be in position in the ovn. 1. Open the oven door by pushing the OPEN DOOR button.
Operating Instruction 3-4 Variable Power Cooking Chart Operation: Set the COOKING POWER CONTROL knob to the appropriate power level by turning it. OUTPUT POWER LEVEL M1912 FULL HIGH REHEAT MEDIUM HIGH MEDIUM MEDIUM LOW DEFROST LOW / KEEP WARM 1000W 850W 700W 600W 450W 300W 180W 100W 3-5 Adjusting the Cooking Time During Cooking Stopping the Cooking To stop the cooking.... Press.... Temporarily Open Door. To resume cooking, close the door.
4. Disassembly & Reassembly 4-1 Replacement of Magnetron, Motor Assembly and Lamp Remove the magnetron including the shield case, permanent magnet, choke coils and capacitors (all of which are contained in one assembly). Lamp Cover Air Thermo S/W 1. Disconnect all lead wires from the magnetron and lamp. 2. Remove a screw securing the magnetron supporter. 3. Remove the magnetron supporter. 4. Remove the air cover. 5. Remove screws securing the magnetron to the wave guide. 6.
Disassembly & Reassembly 4-3 Replacement of Door Assembly 4-3-1 Removal of Door "C" Insert flat screwdriver into the gap between Door "A" and Door "C" to remove Door "C". Be careful when handling Door "C" because it is fragile. Then remove the door assembly. Door "A" Door "C" 4-3-2 Removal of Door "E" Following the procedure as shown in the figure, insert and bend a thin metal plate between Door "E" and Door "A" until you hear the 'tick' sound. • Insertion depth of the thin metal plate should be 0.
Disassembly & ReaAssembly 4-3-5 Reassembly Test After replacement of the defective component parts of the door, reassemble it and follow the instructions below for proper installation and adjustment so as to prevent an excessive microwave leakage. 1. When mounting the door to the oven, be sure to adjust the door parallel to the bottom line of the oven face plate by moving the upper hinge and lower hinge in the direction necessary for proper alignment. 2.
5. Alignment and Adjustments PRECAUTION 1. High voltage is present at the high voltage terminal of the high voltage transformer during any cook cycle. 2. It is neither necessary nor advisable to attempt measurement of the high voltage. 3. Before touching any oven components, or wiring, always unplug the oven from its power source and discharge the high voltage capacitor. 5-1 High Voltage Transformer 1. Remove connectors from the transformer terminals and check continuity. 2.
Alignment and Adjustments 5-3 High Voltage Capacitor 1. Check continuity of the capacitor with meter set at the highest ohm scale. 2. Once the capacitor is charged, a normal capacitor shows continuity for a short time, and then indicates 10MΩ. 3. A shorted capacitor will show continuous continuity. 4. An open capacitor will show constant 10MΩ. 5. Resistance between each terminal and chassis should read infinite. 5-4 High Voltage Diode 1. Isolate the diode from the circuit by disconnecting its leads. 2.
Alignment and Adjustments 5-6 Output Power of Magnetron CAUTION MICROWAVE RADIATION PERSONNEL SHOULD NOT ALLOW EXPOSWRE TO MICROWAVE RADIATION FROM MICROWAVE GENERATOR OR OTHER PARTS CONDUCTING MICROWAVE ENERGY. The output power of the magnetron can be measured by performing a water temperature rise test. Equipment needed * Two 1-liter cylindrical borosilicate glass vessel (Outside diameter of 190mm) * One glass thermometer with mercury column NOTE: Check line voltage under load.
Alignment and Adjustments 5-8 Procedure for Measurement of Microwave Energy Leakage 1) Pour 275±15cc of 20±5˚C(68±9˚F) water in a beaker which is graduated to 600cc, and place the beaker in the center of the oven. 2) Start to operate the oven and measure the leakage by using a microwave energy survey meter. 3) Set survey meter with dual ranges to 2,450MHz. 4) When measuring the leakage, always use the 2 inch spacer cone with the probe. Hold the probe perpendicular to the cabinet door.
6. Troubleshooting WARNING FOR HIGH VOLTAGE 4000 VOLTS EXIST AT THE HIGH VOLTAGE AREA. DO NOT OPERATE THE OVEN WITH CABINET PARTS REMOVED. DO NOT REMOVE THE CABINET PARTS IF THE POWER SUPPLY CORD IS PLUGGED IN THE WALL OUTLET. UNPLUG THE POWER CORD BEFORE SERVICING. 6-1 Electrical Malfunction Parts Fuse blows out when door is opened. Fuse is open. Oven lamp does not light. Fan does not operate. Cause Diagnosis Remedy Defective primary interlock switch ary winding.
Troubleshooting 6-1 Electrical Malfunction (Continved) Parts Cause Diagnosis Remedy 1) Too small a load If a small amount of food is heated for a long time, period of microwave may turn off during operation. To increase the oven load, add a glass of water into the oven. 2) Defective magnetron thermal cutout S/W Check to see if the magnetron thermal cutout switch is activated at a temperature higher than 150˚C. Replace thermal cutout switch. Electric shock is felt.
Troubleshooting 6-2 Unsatisfactory Cooking Parts - Food is not heated. Cause Diagnosis Remedy 1) Open cathode of magnetron Check the terminals with a multimeter to see if the heater circuit is open. Replace magnetron. 2) Defective H. V. Diode Check the H. V. Diode for continuity in the reverse and normal directions using megger. If there is continuity in the reverse direction, the H. V. Diode may be faulty. (In this event H. V. Capacitor will be hot) Replace H. V. Diode.
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Exploded Views and Parts List 7-2 Main Parts List Ref. No. M1 M2 M3 M4 M5 M6 M7 M8 M9 M10 M12 M13 M14 M15 M16 M17 M18 M19 M20 M21 M22 M23 M24 M25 M26 M27 M28 M29 M30 M31 Parts No.
Exploded Views and Parts List 7-3 Assembly Door Parts List Ref. No. Parts No. D1 D2 D3 D4 D5 D6 D7 DE64-40317D DE67-20197A DE94-00075B DE64-40012A DE64-40006F DE61-70032A DE01-00118A Description DOOR-A SCREEN-DOOR ASSY DOOR-E DOOR-C DOOR-KEY SPRING-KEY FILM-DOOR Specification Q'ty ABS,T2.0,-,-,-,M1912 S1,-,-,-,-,3RD-1.0 3RD-1.0,BLK,COATING RESIN-PP(TB53),T2.0,CE945GF,BL POM(F20-02),-,-,12G,BLK,MW7897G,NO-TALK ES,HSWR,PI0.6,D5.4,L25,MW8640T T0.
Exploded Views and Parts List 7-6 Standard Parts List Parts No.
8. Wiring Diagram Wiring Diagram ASSY NOISE FILTER BRN MGT TCO BLK CAVITY TCO PRIMARY S/W BLK BRN BRN H. V. TRANS FUSE 250V10A COM 230V BRN BLK YEL 21V BLU WHT D/M F/M 0V 500k T/M COM MONITOR S/W NC YEL H. V. C (0.91uF) NO H. V. FUSE (0.75A) INRUSH COIL 2200pF 1mH BLU BLK ORG T-MOTOR L 230V D-MOTOR F-MOTOR 0.1uF POWER CORD 230V50HZ LAMP 230V40W 2200pF L F YEL N FA MAGNETRON MONITOR FUSE(1.6A) H. V.
