Dacor DMO2420 Parts And Service Manual
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Dacor DMO2420 Parts And Service Manual

Dacor DMO2420 Parts And Service Manual

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DMO2420
Microwave
Parts and Service Manual

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Summary of Contents for Dacor DMO2420

  • Page 1 DMO2420 Microwave Parts and Service Manual...

  • Page 2: Warning To Service Personnel

    DMO2420B DMO2420R DMO2420S WARNING TO SERVICE PERSONNEL Microwave ovens contain circuitry capable of pro- ducing 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 Trans- former, Magnetron, High Voltage Rectifier Assem- bly, High Voltage Harness etc..

  • Page 3: Microwave Measurement Procedure

    DMO2420B DMO2420R DMO2420S MICROWAVE MEASUREMENT PROCEDURE A. Requirements: 1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven should not exceed 1mW/cm at any point 5cm or more from the external surface of the oven, measured prior to 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.
  • Page 4 MICROWAVE OVEN DMO2420B/DMO2420R/DMO2420S GENERAL INFORMATION FOREWORD This Manual has been prepared to provide Dacor Service Personnel OPERATION with Operation and Service Information for the DACOR MICRO- WAVE OVENS, DMO2420B, DMO2420R and DMO2420S. It is recommended that service personnel carefully study the entire text...

  • Page 5: Specification

    DMO2420B DMO2420R DMO2420S SPECIFICATION ITEM DESCRIPTION Power Requirements 120 Volts / 13.8 Amperes 60 Hertz Single phase, 3 wire grounded Power Output 1200 watts (IEC TEST PROCEDURE) Operating frequency of 2450MHz Case Dimensions Width 24" Height 13-3/8" Depth 19-1/8" Cooking Cavity Dimensions Width 17-3/8"...

  • Page 6: Oven Diagram

    DMO2420B DMO2420R DMO2420S Where a two-pronged wall-receptacle is encountered, it is the personal Grounded responsibility and obligation of the customer to contact a qualified Receptacle Box electrician and have it replaced with a properly grounded three-pronged wall receptacle or have a grounding adapter properly grounded and polarized.

  • Page 7: Description Of Operating Sequence

    DMO2420B DMO2420R DMO2420S OPERATION DESCRIPTION OF OPERATING SEQUENCE the secondary interlock switch and primary interlock The following is a description of component functions during relay and is mechanically associated with the door so that oven operation. it will function in the following sequence. (1) When the door opens from the closed position, the OFF CONDITION primary interlock relay (RY2) and secondary interlock...
  • Page 8 DMO2420B DMO2420R DMO2420S The time of supplementary cooking is determined by experi- ment with each food category and inputted into the LSI. An example of how sensor works: (POTATOES) 1. Potatoes at room temperature. Vapor is emitted very slowly. 2. Heat Potatoes. Moisture and humidity is emitted rapidly. You can smell the aroma as it cooks.
  • Page 9 DMO2420B DMO2420R DMO2420S SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED. NOTE: Indicates components with potential above 250 V. 2. CLOCK APPEARS ON DISPLAY. MAGNETRON MONITOR TEMP. FUSE 20A FUSE COM. N.O. CAPACITOR 1.0µF AC 2300V (RY-2) (RY-1) PRIMARY INTERLOCK RELAY CONTROL UNIT N.O.

  • Page 10: Description And Function Of Components

    DMO2420B DMO2420R DMO2420S DESCRIPTION AND FUNCTION OF COMPONENTS DOOR OPEN MECHANISM open, the monitor fuse blows simultaneously with closing of the monitor switch contacts. The door is opened by pushing the open button on the control CAUTION: BEFORE REPLACING A BLOWN MONITOR panel, refer to the Figure D-1.

  • Page 11: Troubleshooting Guide

    DMO2420B DMO2420R DMO2420S TROUBLESHOOTING GUIDE Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected. When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the checks. Many of the possible causes of trouble will require that a specific test be performed.

  • Page 12: Test Procedure

    DMO2420B DMO2420R DMO2420S CK = Check / RE = Replace TEST PROCEDURE A B C D E E F F G H J K L M N RE RE RE RE CK CK CK CK POSSIBLE CAUSE DEFECTIVE PARTS PROBLEM CONDITION Home fuse or circuit breaker blows when power cord is plugged into wall receptacle.

  • Page 13: Test Procedures

    DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER MAGNETRON ASSEMBLY TEST 1. Disconnect the power supply cord, and then remove outer case. 2. Open the door and block it open. 3. Discharge high voltage capacitor. 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 1 ohm.
  • Page 14 DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER (HIGH VOLTAGES ARE PRESENT AT THE HIGH VOLTAGE TERMINAL, SO DO NOT ATTEMPT TO MEASURE THE FILAMENT AND HIGH VOLTAGE.) HIGH VOLTAGE RECTIFIER TEST 1. Disconnect the power supply cord, and then remove outer case. 2.
  • Page 15 DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 5. Reconnect all leads removed from components during testing. 6. Reinstall the outer case (cabinet). 7. Reconnect the power supply cord after the outer case is installed. 8. Run the oven and check all functions. CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERA- TURE, REPLACE TEMPERATURE FUSE.

  • Page 16: Component Test

    DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER with the door opened (in this condition the plunger of the monitor switch is pushed in), the meter should indicate an open circuit. If improper operation is indicated, the switch may be defective. After testing the monitor switch, reconnect the wire lead to the monitor switch (COM) terminal and check the continuity of the monitor circuit.

  • Page 17: Key Unit Test

    DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 4) Reconnect the power supply cord after the outer case is installed. 5) Run the oven and check all functions. The following symptoms indicate a defective key unit. a) When touching the pads, a certain pad produces no signal at all. b) When touching a number pad, two figures or more are displayed.

  • Page 18: Relay Test

    DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER may be used (after clearing the control unit) to determine if the control unit or key pad is at fault. 5. Reconnect all leads removed from components during testing. 6. Re-install the outer case (cabinet). 7.

  • Page 19: Foil Pattern On The Printed Wiring Board Test

    DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER MENU 1ST STAGE 2ND STAGE Steaks, chops or fish LEVEL TIME LEVEL TIME 0.5lb 30sec. 15sec. (5) If improper operation is indicated, the control unit is probably defective and should be checked. FOIL PATTERN ON THE PRINTED WIRING BOARD TEST To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the PWB, this foil pattern acts as a fuse.

  • Page 20: Ah Sensor Test

    DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 10) Discharge high voltage capacitor. 11) Reconnect all leads removed from components during testing. 12) Re-install the outer case (cabinet). 13) Reconnect the power supply cord after the outer case is installed. 14) Run the oven and check all functions.

  • Page 21: Checking Control Unit

    DMO2420B DMO2420R DMO2420S TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER 9-3. Close the door. 9-4. Touch the Timer/Clock pad once, the Power Level pad twice, the Start pad once and the number pad 1 once. 9-5. The control panel is in automatic Sensor operation. 9-6.

  • Page 22: Touch Control Panel Assembly

    DMO2420B DMO2420R DMO2420S TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL 4) Relay Circuit The touch control section consists of the following units. A circuit to drive the magnetron, fan motor, turntable motor and light the oven lamp. (1) Key Unit (2) Control Unit (The Control Unit consists of Power Unit 5) Buzzer Circuit and LSI Unit).
  • Page 23 DMO2420B DMO2420R DMO2420S LSI(IXA098DR) The I/O signal of the LSI(IXA098DR) is detailed in the following table. Pin No. Signal Description COM5 Common data signal : COM11. Connected to LCD signal COM11. COM4 Common data signal : COM12. Connected to LCD signal COM12. COM3 Common data signal : COM13.
  • Page 24 DMO2420B DMO2420R DMO2420S Pin No. Signal Description INT0 Signal synchronized with commercial power source frequency. H : GND This is the basic timing for time processing of LSI. L : -5V 16.7 msec. Key strobe signal. Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16 and P17 terminal while one of G1 line keys on key matrix is touched.
  • Page 25 DMO2420B DMO2420R DMO2420S Pin No. Signal Description Terminal not used. XCOUT Terminal not used. XCIN Connected to VC. Terminal not used. Power source voltage: GND(0V). The power source voltage to drive LSI is input to VCC terminal. OSCSEL Connected to VC(-5V). XOUT Internal clock oscillation output.

  • Page 26: Absolute Humidity Sensor Circuit

    DMO2420B DMO2420R DMO2420S Pin No. Signal Description COM7 Common data signal : COM9. Connected to LCD signal COM9. COM6 Common data signal : COM10. Connected to LCD signal COM10. ABSOLUTE HUMIDITY SENSOR CIRCUIT LSI are turned on in such a way as to change the (1) Structure of Absolute Humidity Sensor resistance values in parallel with R98 ~ R102.

  • Page 27: Touch Control Panel Servicing

    DMO2420B DMO2420R DMO2420S TOUCH CONTROL PANEL SERVICING 4) Re-install the outer case (cabinet). 1. Precautions for Handling Electronic Components 5) Re-connect the power supply cord after the outer This unit uses CMOS LSI in the integral part of the case is installed. circuits.

  • Page 28: Component Replacement And Adjustment Procedure

    DMO2420B DMO2420R DMO2420S COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE WARNING AGAINST HIGH VOLTAGE: Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts may result in severe, possibly fatal, electric shock. (Example) High Voltage Capacitor, Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness etc.. Avoid possible exposure to microwave energy.

  • Page 29: Power Transformer Removal

    DMO2420B DMO2420R DMO2420S CAUTION: 1. DISCONNECT OVEN FROM POWER SUP PLY BEFORE REMOVING OUTER CASE. 2. DISCHARGE THE HIGH VOLTAGE CA- PACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING. Special screw NOTE: When replacing the outer case, the 2 special Torx screws must be reinstalled in the same locations.

  • Page 30: Oven Lamp And Lamp Socket Removal

    DMO2420B DMO2420R DMO2420S OVEN LAMP AND LAMP SOCKET REMOVAL 1. Disconnect the power supply cord and remove outer case. Oven lamp 2. Open the door and block it open. socket 3. Discharge high voltage capacitor. 4. Remove the oven lamp from the oven lamp socket. Terminal 5.

  • Page 31: Cooling Fan Motor Removal

    DMO2420B DMO2420R DMO2420S COOLING FAN MOTOR REMOVAL REMOVAL CAUTION: 1. Disconnect the power supply cord and then remove outer * Do not reuse the removed fan blade because the hole case. (for shaft) may be larger than normal. 2. Open the door and block it open. 3.

  • Page 32: Door Sensing Switch/Secondary Interlock Switch And Monitor Switch Adjustment

    DMO2420B DMO2420R DMO2420S monitor switches are in the lower position and the door 3. Secure latch hook (with two (2) mounting screws) to oven sensing switch is in the upper position. flange. 2. Re-connect wire leads to each switch. 4. Make sure that the monitor switch is operating properly Refer to pictorial diagram.

  • Page 33: Sealer Film

    DMO2420B DMO2420R DMO2420S 13.Now, door panel is free. Note: The door on a microwave oven is designed to act as 14.Slide latch head upward and remove it from door frame an electronic seal preventing the leakage of by releasing latch spring from door frame and latch head. microwave energy from oven cavity during cook 15.Now, latch head and latch spring are free.
  • Page 34 NOTE: The grounding conductor of the power supply cord has been grounded by power supply cord fixing screw. CAVITY TEMP. FUSE The screw must always be MAGNETRON TEMP. FUSE kept tight. CN-F AH SENSOR POWER SUPPLY CORD 120V 60Hz DOOR CONTROL PANEL N.O.
  • Page 35 DMO2420B DMO2420R DMO2420S CN-C 12PIN LEAD WIRE HARNESS Q2 2SB1238 R4 27 R5 4.7k D1-D4 11ES1 CN-A 1SS270A 1SS270A – – R3 510 1/2w Q1 2SB1238 R2 680 1/2w SP1 PKM22EPT Q3 KRC243M BUZZER OVEN LAMP R6 3.3k TURNTABLE OVEN LAMP MOTOR TURNTABLE FAN MOTOR...
  • Page 36 CN-C DTA143EAK 0.1µ/50v 0.1µ/50v SENSOR DEFROST TURNTABLE OFF COOK – HELP 0.1µ/50v 0.1µ/50v LD10 LD11 LD12 LD13 C-10 MA152WA 4.7k 330 1w 3.32kD COM5 SEG34 DTA143EAK COM4 SEG35 COM3 SEG36 COM2 SEG37 COM1 SEG38 IC-2 OVEN LAMP COM0 SEG39 BA4558 0.01µ/25v SEG40 TURNTABLE...
  • Page 37 DMO2420B DMO2420R DMO2420S (CN - C) CN - C CN - B CN - A (J1) (CN - D) (D10) Figure S-4. Printed Wiring Board of Power Unit...
  • Page 38 Technical Service 950 S. Raymond Ave. Pasadena, CA 91105 800-353-2267 Part # 85927...

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