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MMD24S
MMD24B
SERVICE MANUAL
S38M289MMD24S
MICROWAVE DRAWER
MODELS
MMD24S
MMD24B
In the interest of user-safety the unit should be restored to its original condition and only parts identical to those specified should
be used.
WARNING TO SERVICE PERSONNEL:
This service manual is intended for use by persons having electrical and mechanical training and a level of
knowledge of these subjects generally considered acceptable in the appliance repair trade. Sharp Electronics
Corporation cannot
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MMD24S MMD24B PRECAUTIONS TO BE OBSERVED BEFORE AND DUR- ING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY (a) Do not operate or allow the oven to be operated with the door open. (b) Make the following safety checks on all ovens to be serviced before activating the magnetron or other microwave source, and make repairs as necessary: () interlock operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening o
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MMD24S MMD24B WARNING TO SERVICE PERSONNEL Microwave Oven units contain circuitry capable of producing very high voltage and current, contact with following parts may result in a severe, possibly fatal, electrical shock. (Example) High Voltage Capacitor, High Voltage Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness, Heating Elements, etc.. Read the Service Manual carefully and follow all instructions. Before Servicing When the testing is completed, .
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MMD24S MMD24B MICROWAVE MEASUREMENT PROCEDURE A. Requirements: ) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave 2 oven should not exceed mW/cm at any point 5cm or more from the external surface of the oven, measured prior to 2 acquisition by a purchaser, and thereafter (through the useful life of the oven), 5 mW/cm at any point 5cm or more from the external surface of the oven. 2) Safety interlock switches: Primary interloc
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MMD24S MMD24B SERVICE MANUAL PRODUCT DESCRIPTION MICROWAVE DRAWER MMD24S / MMD24B SCHEMATICS FOREWORD This Manual has been prepared to provide Dacor Service Personnel TEST PROCEDURE with Operation and Service Information for the DACOR MICROWAVE DRAWER. It is recommended that service personnel carefully study the entire text of this manual so that they will be qualified to render satisfactory TOUCH CONTROL PANEL customer service. Check the interlock switches and the door seal carefully. Spec
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MMD24S MMD24B MICROWAVE DRAWER SPECIFICATION ITEM DESCRIPTION Power Requirements Canada - 7 Volts / 3.0 Amperes / 500 Kw / 60 Hz (CUL) U.S.A. - 20 Volts / 3.6 Amperes / 500 Kw / 60 Hz (UL) Single phase, 3 wire grounded Power Output 950 watts (IEC TEST PROCEDURE) Operating frequency of 2450MHz Cooking Cavity Dimensions Width 7-/32 Height 5-7/8" .0 Cubic F eet Depth 7-/8" Outside Dimensions Width 23-3/6" Hei
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MMD24S MMD24B GENERAL INFORMATION GROUNDING INSTRUCTIONS This oven is equipped with a three prong grounding plug. It must be plugged into a wall receptacle that is properly installed and grounded in accordance with the National Electrical Code and local codes and ordinances. In the event of an electrical short circuit, grounding reduces the risk of electric shock by providing an escape wire for the electric current. WARNING: Improper use of the grounding plug can result in a risk of electric s
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MMD24S MMD24B OPERATION DESCRIPTION OF OPERATING SEQUENCE The following is a description of component functions dur- the secondary interlock switch and secondary interlock ing oven operation. relay and is mechanically associated with the drawer so that it will function in the following sequence. 8. When the drawer opens from the closed position, the OFF CONDITION primary interlock relay (RY2) and secondary interlock Closing the drawer activates the door sensing switch and switch open their
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MICROWAVE MICROWAVE MMD24S MMD24B SENSOR COOKING CONDITION 2. The coil of shut-off relay (RY-) is energized, but the Using the SENSOR function, food is cooked without figur- power transformer is not turned on. ing time, power level or quantity. When the oven senses 3. After about 6 seconds, the cook relay (RY-2) is enough steam from the food, it relays the information to its energized. The power transformer is turned on, microprocessor which will calculate the remaining cooking micro
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MAGNETRON H.V. RECTIFIER CAPACITOR xxx µF AC 2300V POWER TRANSFORMER WHT N.C. COM WHT N.O. RED or BLK MONITOR SWITCH BLU BRN GRN M5 GRN GRY GRN M4 RED or BLK GRN GRN WHT PRIMARY INTERLOCK RELAY GRY M1 M3 GRN RY2 STIRRER MOTOR BLK N5 SM ORG or BLU YLW N4 YLW FAN MOTOR RY3 N3 BLU FM N2 GRY RED *2 or BLK *2 ORG RY4 N1 OVEN LAMP RED OL RED *2 WHT WHT WHT or BLK *2 GRY WHT RY1 F3 F2 RY5 F1 HUMDITY SENSOR RED GRN GRY BLK WHT GRY "TO LOAD" "TO LOAD" 0.0033 µF 250V 0.0033 µF 250V LINE BYPASS CAPACITOR L
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MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER A TOUCH CONTROL PANEL ASSEMBLY TEST The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and ohmmeter. In this service manual, the touch control panel assembly is divided into three units, Control Unit, Keyboard Unit and Power Unit, and troubleshoo
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MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 4) Reconnect all leads removed from components during testing. 5) Re-install the covers. 6) Reconnect the power supply cord after the covers are installed. 7) Run the oven and check all functions. B KEY UNIT TEST . Disconnect the power supply cord, and then remove outer case. 2. Open the drawer and block it open. 3. Discharge high voltage capacitor. 4. If the display fails to clear when the STOP/
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MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 2. Re-install the outer case (cabinet). 3. Reconnect the po wer supply cord after the outer case is installed. 4. Run the o ven and check all function. D DEFROST TEST WARNING : The oven should be fully assembled before following procedure. () Place one cup of water in the center of the tray in the oven cavity. (2) Close the drawer, touch the Defrost pad. Then select Steaks/Chops by touching the number pad 2. And touch
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MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER ) Discharge high voltage capacitor. 2) Reconnect all leads removed from components during testing. 3) Re-install the outer case (cabinet). 4) Reconnect the power supply cord after the outer case is installed. 5) Run the oven and check all functions. F AH SENSOR TEST Checking the initial sensor cooking condition WARNING : The oven should be fully assembled before following procedur
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MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 9-2. Place the container on the center of tray in the oven cavity. 9-3. Close the drawer. 9-4. Touch the TIMER/CLOCK pad once, the POWER LEVEL pad twice and the START pad once. And touch the number pads once and the number pad 4 once. 9-5. The control panel is in automatic Sensor operation. 9-6. The oven turns off automatically, and the time for detecting moisture will be displayed. If new sensor does not operate properly
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MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER Refer to the disassembly instructions found on Page 27. G MAGNETRON ASSEMBLY TEST . Disconnect the power supply cord. 2. Open the drawer and keep it open. 3. To discharge high voltage capacitor, wait for 60 seconds. 4. To test for an open filament, isolate the magnetron from the high voltage circuit. A continuity check across the magnetron filament leads should indicate less than ohm. 5. To
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MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER I SECONDARY INTERLOCK SWITCH TEST . Disconnect the power supply cord. 2. Open the drawer and keep it open. 3. To discharge high voltage capacitor, wait for 60 seconds. 4. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the switch. The meter should indicate an open circuit with the drawer open and a closed circuit with the drawer closed. If im
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MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER L BLOWN MONITOR FUSE TEST . Disconnect the power supply cord. 2. Open the drawer and block it open. 3. To discharge high voltage capacitor, wait for 60 seconds. 4. If the monitor fuse is blown when the drawer is opened, check the primary interlock switch, secondary interlock switch and monitor switch according to the "TEST PROCEDURE" for those switches before replacing the blown monitor fuse.
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MMD24S MMD24B TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units. 6) Power Source Circuit This circuit generates voltages necessary in the control () Key unit unit from the AC line voltage. (2) Control Unit In addition, the synchronizing signal is available in order (3) Power unit to compose a basic standard time in the clock circuit. Symbol Voltage Application The principal functions of these units and the signal
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MMD24S MMD24B DESCRIPTION OF LSI (IC-1) The I/O signal of the LSIis detailed in the following table. Pin No. Signal I/O Description - 3 AN5- AN3 IN Terminal to change cooking input according to the Model. By using A/D converter contained in the LSI, DC voltage in accordance with the Model in operation is applied to set up its cooking constant. 4 AN2 IN Input signal which inform the drawer door is in the middle position between the opened position and the closed position, to LSI from
