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.
MMD24S MMD24B PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY (a) Do not operate or allow the oven to be operated with the door open.
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 1. Disconnect the power supply cord remove cabinet.
MMD24S MMD24B 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/cm2 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/cm2 at any point 5cm or more from the external surface of the oven.
MMD24S MMD24B SERVICE MANUAL PRODUCT DESCRIPTION MICROWAVE DRAWER MMD24S / MMD24B SCHEMATICS FOREWORD This Manual has been prepared to provide Dacor Service Personnel with Operation and Service Information for the DACOR MICROWAVE DRAWER. TEST PROCEDURE It is recommended that service personnel carefully study the entire text of this manual so that they will be qualified to render satisfactory customer service. TOUCH CONTROL PANEL Check the interlock switches and the door seal carefully.
MMD24S MMD24B MICROWAVE DRAWER SPECIFICATION ITEM Power Requirements DESCRIPTION Canada - 117 Volts / 13.0 Amperes / 1500 Kw / 60 Hz (CUL) U.S.A. - 120 Volts / 13.6 Amperes / 1500 Kw / 60 Hz (UL) Single phase, 3 wire grounded Power Output 950 watts (IEC TEST PROCEDURE) Operating frequency of 2450MHz Cooking Cavity Dimensions Width 17-11/32 Height 5-7/8" 1.
GENERAL INFORMATION MMD24S MMD24B 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 shock.
MMD24S MMD24B OPERATION DESCRIPTION OF OPERATING SEQUENCE The following is a description of component functions during oven operation. the secondary interlock switch and secondary interlock 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 primary interlock relay (RY2) and secondary interlock switch open their contacts. And contacts of the relay (RY1) remains closed.
MMD24S MMD24B SENSOR COOKING CONDITION 2. The coil of shut-off relay (RY-1) is energized, but the power transformer is not turned on. 3. After about 16 seconds, the cook relay (RY-2) is energized. The power transformer is turned on, microwave energy is produced and first stage is started. The 16 seconds is the cooling time required to remove any vapor from the oven cavity and sensor. Using the SENSOR function, food is cooked without figuring time, power level or quantity.
FUSE 20A "TO SOURCE" BLK 10 GRN GRY WHT RY2 N3 BLU N2 RY1 "TO LOAD" DM GRN GRN M1 DOOR SENSING SWITCH M5 GRN GRY GRN GRN N5 BLK N4 YLW N1 ORG WHT DOOR POSITION SWITCH REAR BLU DOOR POSITION SWITCH FRONT GRN*2 M4 MICROWAVE DRAWER DOOR OPEN-CLOSE MOTOR PRIMARY INTERLOCK RELAY RY5 MICROWAVE DRAWER WHT GRY COM RY4 CN502 H9 3 RY3 CONTROL UNIT N.O. "TO LOAD" WHT GRY E3 MONITOR SWITCH NOISE SUPRESSION COIL LINE CROSS CAPACITOR 1.
TEST PROCEDURES PROCEDURE LETTER A MMD24S MMD24B COMPONENT TEST 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.
MMD24S MMD24B TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 4) 5) 6) 7) B Reconnect all leads removed from components during testing. Re-install the covers. Reconnect the power supply cord after the covers are installed. Run the oven and check all functions. KEY UNIT TEST 1. Disconnect the power supply cord, and then remove outer case. 2. Open the drawer and block it open. 3. Discharge high voltage capacitor. 4.
MMD24S MMD24B TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 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 function. D DEFROST TEST WARNING : The oven should be fully assembled before following procedure. (1) 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 the number pad 5.
MMD24S MMD24B TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 11) 12) 13) 14) 15) F Discharge high voltage capacitor. Reconnect all leads removed from components during testing. Re-install the outer case (cabinet). Reconnect the power supply cord after the outer case is installed. Run the oven and check all functions. AH SENSOR TEST Checking the initial sensor cooking condition WARNING : The oven should be fully assembled before following procedure.
MMD24S MMD24B TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 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 1 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.
MMD24S MMD24B TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST Refer to the disassembly instructions found on Page 27. G MAGNETRON ASSEMBLY TEST 1. 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 1 ohm. 5.
MMD24S MMD24B TEST PROCEDURES PROCEDURE COMPONENT TEST LETTER I SECONDARY INTERLOCK SWITCH TEST 1. 2. 3. 4. 5. 6. 7. 8. J Disconnect the power supply cord. Open the drawer and keep it open. To discharge high voltage capacitor, wait for 60 seconds. 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.
MMD24S MMD24B TEST PROCEDURES PROCEDURE LETTER L COMPONENT TEST BLOWN MONITOR FUSE TEST 1. 2. 3. 4. Disconnect the power supply cord. Open the drawer and block it open. To discharge high voltage capacitor, wait for 60 seconds. 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.
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 unit from the AC line voltage. In addition, the synchronizing signal is available in order to compose a basic standard time in the clock circuit. (1) Key unit (2) Control Unit (3) Power unit The principal functions of these units and the signals communicated among them are explained below.
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 1 - 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.
MMD24S MMD24B Pin No. Signal I/O 27 COM0 OUT 28 VL3 IN 29 - 31 P27- P25 OUT 32 SEG20 OUT 33 P23 IN Description 45 P07 OUT Common data signal. Connected to LCD signal C4. Connected VC (+5V). Terminal not used. Segment data signal. Connected to LCD segment S24. Signal coming from touch key. When any one of J-4 line keys on key matrix is touched, a corresponding signal from P10P17 will be input into P23. When no key is touched, the signal is held at "L" level.
MMD24S MMD24B Pin No. Signal I/O 47 P05 OUT 48-52 P04-P00 OUT 53 P57 OUT Description Magnetron high-voltage circuit driving signal. To turn on and off the cook relay(RY2). In 100% power operation, the signals holds “H” level during microwave cooking and “L” level while not cooking. In other cooking modes (90%, 80%, 70%, 60%, 50%, 40%, 30%, 20%, 10%, 0%) the signal turns to “H” level and “L” level in repetition according to the power level.
MMD24S MMD24B HUMIDITY SENSOR CIRCUIT (1) Structure of Humidity Sensor The humidity sensor includes two thermistors as shown in the illustration. One thermistor is housed in the closed vessel filled with dry air while another in the open vessel. Each sensor is provided with the protective cover made of metal mesh to be protected from the external airflow. the resistance values results in that there is the same potential at both F-3 terminal of the absolute humidity sensor and AN6 terminal of the LSI.
MMD24S MMD24B TOUCH CONTROL PANEL SERVICING A. On some models, the power supply cord between the touch control panel and the oven itself is so short that the two can’t be separated. For those models, check and repair all the controls (sensor-related ones included) of the touch control panel while keeping it connected to the oven. B. On some models, the power supply cord between the touch control panel and the oven proper is long enough that they may be separated from each other.
MMD24S MMD24B PRECAUTIONS FOR USING LEAD-FREE SOLDER 1. Employing lead-free solder The "Main PWB" of this model employs lead-free solder. This is indicated by the "LF" symbol printed on the PWB and in the service manual. The suffix letter indicates the alloy type of the solder. Example: Indicates lead-free solder of tin, silver and copper. 2. Using lead-free wire solder When repairing a PWB with the "LF" symbol, only lead-free solder should be used.
MMD24S MMD24B COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE WARNING AGAINST HIGH VOLTAGE: Microwave ovens contain circuitry capable of producing very high voltage and current. Contact with the 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.. WARNING: To Avoid possible exposure to microwave energy, please follow the instructions below before operating the oven. 1.
MMD24S MMD24B MICROWAVE DRAWER DISASSEMBLY WARNING: Follow all safety precautions as stated at the beginning of this Service Manual before proceeding! 1. Before removing Microwave Drawer, take measures to protect the Drawer louver by either removing the louver or by letting the louver over hang off flat protected surface (Fig 1). Fig. 1 2. Open the Drawer to access the 4 mounting screws holding the unit on to the wall or cabinet opening. (Fig 1). Louver 3.
MMD24S MMD24B 7. To remove the Control Panel Frame Assembly, remove the 9 screws holding the C/P frame to the cavity. (Fig 3). With the C/P frame assembly now loose, you can unplug all wires. Fig. 3 At this point, you will have access to all parts of the Microwave Drawer. POWER CORD REPLACEMENT 1. Un-hook the black and white AC terminals from the Noise Filter PWB and green ground wire from the back plate. (Fig 4). 2.
MMD24S MMD24B STOP SWITCH, SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH REMOVAL 1. Follow the Microwave Drawer disassembly as previously stated 2. Open the drawer and keep it open. in the top position, located on the left side of the unit. 3. To discharge the high voltage capacitor, wait for 60 The door sensing switch by itself on the right side of the seconds. unit. 4. Remove the screw holding the latch hook to the oven 2. Re-connect wire leads to each switch. Refer to pictorial flange. diagram. 5.
MMD24S MMD24B DRAWER/SLIDE RAIL REMOVAL DRAWER ASSEMBLY AND CHOKE REMOVAL 1. Follow the Microwave Drawer disassembly as previously stated 2. Open the drawer and keep it open. 3. To discharge the high voltage capacitor, wait for 60 seconds. 4. Remove the both right and left side panels. 5. Remove (2) Drawer Support Covers from Choke Cover as shown in (Fig. D-1). 6. Insert a putty knife (thickness of about 0.5mm) into the gap between the choke cover and the door frame. 7.
MMD24S MMD24B SWITCH ANGLE REMOVAL/ADJUSTMENT SWITCH ANGLE REMOVAL Fig. S-1 (Locate either the right or left switch angle) 1. 2. 3. 4. Follow the Microwave Drawer disassembly as previously stated Open the drawer and keep it open. To discharge the high voltage capacitor, wait for 60 seconds. To remove switch, remove screw (1) holding switch to switch angle (Fig. S-1). 5. To replace switch angle, remove bottom cover and remove the 2 screws holding the switch lever (Fig. S-2). 6.
MMD24S MMD24B AUTO DRAWER GEAR REMOVAL/INSTALLATION (This procedure requires a 14" or greater phillips screwdriver) 1. Disengage any power going to the unit. 2. Open the drawer and keep it open. 3. Remove the top cover and right side cabinet. 4. Unhook wiring to Auto Drawer Gear. 5. Remove bottom screw below Auto Drawer Gear (Fig. G-1). 6. Remove the (4) screws holding the auto drawer gear to the bottom cavity angle (Fig. G-2). 7.
MMD24S MMD24B 2 1 4 3 6 5 A A RED H 3 BLK BLK 2 WHT 1 GRN WHT N Power Supply cord 120V 60Hz WHT NOISE FILTER BOARD to Back Plate GRY 4 3 RED CN502 2 GRN B B 1 BLK ORG ORG RED (SWITCHING POWER SUPPLY) BLK or RED ORG CN502 2 BLK 1 GRY 7 RED or BLK GRN CN501 MAGNETRON THERMAL CUT-OUT OVEN THERMAL CUT-OUT 6 WHT 5 4 3 RED WHT WHT RED or BLK N.C. 1 BLU MONITOR SWITCH 3 CNB 2 1 RED THIRD DOOR SWITCH BRN C YLW or ORG N.O. GRY 2 YLW or BLK COM.
MMD24S MMD24B 2 1 CN-A A-7 3 T1 PA154DR FUSE AC 120V 60Hz D1 -- D4 1N4002L x4 5 5 CN-H D4 D1 D3 8 D2 + C1 1 1000uF/50V A-5 6 VR H-1 VRS1 10G471K 0.1uF/50V C2 A 2.5A 4 3 A K-1 GND H-3 K-3 INT B H-2 B K-2 RY5 D12 SW Reg. PWR H-8 K-8 C C H- 9 SW Reg. OUT +24V E-3 J10 H-11 502-3 RY2 MICRO D N.O. D5 D COM RY1 N.O. H-6 K-6 E COM J11 0.1u 250V (C11) COM (O.
FM (RY4) SM (RY3) +24V +24V 502-1 SLIDE M 6 E-1 N-5 N-4 N-3 N-2 N-1 E-3 K-8 K-7 K-5 M-5 K-6 M-3 M-2 M-1 K-4 M-6 M-7 M-4 F-1 F-2 F-3 K-2 K-3 CN-F + CN-N CN-M CN-E 2K 6 5 10uF/35V + D20 7 100 + Q26 Q25 Q95 Q22 1 C20 1.5K R69 KRC101S KRC101S KRC101S R24 10K Q23 4 8 KRC101S 10K R56 10K R58 KIA358 3 IC-5 2 KRC101S KRA102S Q97 R95 100 R96 R22 270 C21 10uF/35V KRC101S Q20 + - KRA224S Q21 10K R21 R41 3.32KD R43 1.
MMD24S MMD24B 1 2 4 3 5 6 A A B B 11 D5 2 RY2 DIP D12 D7 C RY1 CNH C RY5 1 R3 1 J11 C10 J10 N.O. COM. RY3 D CNB D10 D3 D2 D1 D4 C1 1 Q1 D N.O. COM. R10 R1 ZD1 C2 8 1 D11 1 3 RY4 E R11 E T1 F VRS1 4 3 P 7 CNA C11 FUSE F 2.5A 3 G G H H Figure S-4.
1 2 37 3 4 5 6 H H R5 1 R6 2 1 1 R7 WHA 6 CNK C3 + C3 + C21 C4 8 Q3 I C O C5 R22 C20 C2 G 1 + + 9 8 C6 CNM 1 2 ZD4 C5 C6 R11 C10 C8 + C8 R45 R46 1 R18 R21 R106 R105 R104 CNJ CF1 CF1 16 C13 R107 R103 R102 R101 R100 C44 D41 C54 D40 R42 2 J2 2 1 3 J1 J3 J4 J6 K R40 4 CNF 3 3 1 C0 C0 R115 C103 R114 C102 R112 C100 R113 C101 R41 + C90 C90 R68 R98 R96 R99 R95 1 C90 S0 C3 S0 C41 C30 C43 R44 Q24 Q95 1 R36 R38 R37 R35 IC6 5 1 R43 C42 C40 Q96
MMD24S MMD24B COPYRIGHT © 2008 BY DACOR, INC. ALL RIGHTS RESERVED. No part of this publication may be reproduced, stored in retrieval systems, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without prior written permission of the publisher.