MICROWAVE TECHNICAL SERVICE GUIDE Models: ■ MO-24SS
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.
WARNING TO SERVICE PERSONNEL Microwave ovens 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 etc.. Read the Service Manual carefully and follow all instructions. Don't Touch ! Danger High Voltage When the testing is completed, 1.
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.
PRODUCT DESCRIPTION ..........................................................................................................1-2 GENERAL INFORMATION ..........................................................................................................4-5 OPERATION ..........................................................................................................................................6-9 TROUBLESHOOTING ....................................................................................
SPECIFICATION ITEM DESCRIPTION Power Requirements 120 Volts / 13.8 Amperes/1650Watts 60 Hertz Single phase, 3 wire grounded Power Output 1200 watts (IEC-705 TEST PROCEDURE) Operating frequency of 2450MHz Case Dimensions Width 24" Height 13-3/8" Depth 19-1/8" Cooking Cavity Dimensions 2.0 Cubic Feet Width 17-3/8" Height 10-1/2" Depth 18-5/8" Tray Size 15" Control Complement Touch Control System Clock ( 1:00 - 12:59 ) Timer (0 - 99 min.
adapter properly grounded and polarized. If the extension cord must be used, it should be a 3-wire, 15 amp. or higher rated cord. Do not drape over a countertop or table where it can be pulled on by children or tripped over accidentally. CAUTION: DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE ROUND GROUNDING PRONG FROM THIS PLUG. 1. One touch door open button. Push to open door. 2. Door latches. The oven will not operate unless the door is securely closed. 3. Removable turntable support. 4.
OPERATION DESCRIPTION OF OPERATING SEQUENCE the secondary interlock switch and primary interlock relay and is mechanically associated with the door so that it will function in the following sequence. (1) When the door 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. Then the monitor switch contacts close.
2. The coil of shut-off relay (RY-1) is energized, the turntable motor are turned on, 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. SENSOR COOKING CONDITION Using the SENSOR function, food is cooked without figuring time, power level or quantity.
SCHEMATIC NOTE: CONDITION OF OVEN 1. DOOR CLOSED 2. CLOCK APPEARS ON DISPLAY MAGNETRON TEMP. FUSE MONITOR FUSE 20A COM. N.O. A2 CAPACITOR 1.0µF AC 2300V AH SENSOR (RY-2) PRIMARY INTERLOCK RELAY (RY-1) A1 GRN CONTROL UNIT N.O. COM. 120V AC 60 Hz B1 POWER TRANSFORMER B2 N.C. DOOR SENSING SWITCH CAVITY TEMP. FUSE TTM OL TURNTABLE MOTOR OVEN LAMP MONITOR SWITCH FM COM. H.V.
DESCRIPTION AND FUNCTION OF COMPONENTS DOOR OPEN MECHANISM open, the monitor fuse blows simultaneously with closing of the monitor switch contacts. CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE TEST THE DOOR SENSING SWITCH, PRIMARY INTERLOCK RELAY (RY2), RELAY (RY1), SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH FOR PROPER OPERATION. (REFER TO CHAPTER "TEST PROCEDURE"). NOTE: MONITOR FUSE AND MONITOR SWITCH ARE REPLACED AS AN ASSEMBLY.
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. These tests are given a procedure letter which will be found in the "Test Procedure "section.
CK = Check / RE = Replace Home fuse or circuit breaker blows when power cord is plugged into wall receptacle OFF CONDITION Monitor fuse blows when power cord is plugged into wall receptacle. All letters and indicators do not appear in display when power cord is first plugged into wall outlet. Display does not operate properly when STOP/CLEAR key is touched. (Buzzer should sound and ":" or time of day should appear in display.) Oven lamp does not light when door is opened.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 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. To test for a shorted magnetron, connect the ohmmeter leads between the magnetron filament leads and chassis ground. This test should indicate an infinite resistance. If there is little or no resistance the magnetron is grounded and must be replaced. 6.
TEST PROCEDURES PROCEDURE LETTER C COMPONENT TEST HIGH VOLTAGE RECTIFIER TEST 1. 2. 3. 4. Disconnect the power supply cord, and then remove outer case. Open the door and block it open. Discharge high voltage capacitor. Isolate the rectifier from the circuit. Using the highest ohm scale of the meter, read the resistance across the terminals and observe, reverse the leads to the rectifier terminals and observe meter reading.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST CAUTION: IF THE TEMPERATURE FUSE INDICATES AN OPEN CIRCUIT AT ROOM TEMPERATURE, REPLACE TEMPERATURE FUSE. F SECONDARY INTERLOCK SWITCH TEST 1. 2. 3. 4. 5. 6. 7. 8. Disconnect the power supply cord, and then remove outer case. Open the door and block it open. Discharge high voltage capacitor. Isolate the switch and connect the ohmmeter to the common (COM.) and normally open (NO) terminal of the switch.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 5. 6. 7. 8. Reconnect all leads removed from components during testing. Reinstall the outer case (cabinet). Reconnect the power supply cord after the outer case is installed. Run the oven and check all Screw Driver functions. RED WHT/WHT Monitor Switch Ohmmeter Secondary Interlock Switch H BLOWN MONITOR FUSE TEST 1. 2. 3. 4. Disconnect the power supply cord, and then remove outer case. Open the door and block it open. Discharge high voltage capacitor.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 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. c) When touching the pads, sometimes a pad produces no signal. If the Key unit is defective. 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) Replace the Key unit.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST 6. Re-install the outer case (cabinet). 7. Reconnect the power supply cord after the outer case is installed. 8. Run the oven and check all functions.
TEST PROCEDURES PROCEDURE LETTER M COMPONENT TEST 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. 1. Foil pattern check and repairs. 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) Follow the troubleshooting guide given below for repair.
TEST PROCEDURES PROCEDURE LETTER N COMPONENT TEST AH SENSOR TEST Checking the initial sensor cooking condition Warning: The oven should be fully assembled before following procedure. 1) The oven should be plugged in at least two minutes before sensor cooking. o o 2) Room temperature should not exceed 95 F(35 C). 3) The unit should not be installed in any area where heat and steam are generated. The unit should not be installed for example, next to conventional surface unit.
TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST CHECKING CONTROL UNIT (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) Disconnect the sensor connector that is mounted to control panel. (5) Then connect the dummy resistor circuit (see fig.) to the sensor connector of control panel. (6) Disconnect the leads to the primary of power transformer.
TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units. (1) Key Unit (2) Control Unit (The Control Unit consists of Power Unit and LSI Unit). The principal functions of these units and the signals communicated among them are explained below. Key Unit The key unit is composed of a matrix, signals generated in the LSI are sent to the key unit through P00-P07.
LSI(IXA098DR) The I/O signal of the LSI(IXA098DR) is detailed in the following table. Pin No. Signal I/O Description 1 COM5 OUT Common data signal : COM11. Connected to LCD signal COM11. 2 COM4 OUT Common data signal : COM12. Connected to LCD signal COM12. 3 COM3 OUT Common data signal : COM13. Connected to LCD signal COM13. 4 COM2 OUT Common data signal : COM14. Connected to LCD signal COM14. 5 COM1 OUT Common data signal : COM15. Connected to LCD signal COM15.
Pin No. 34 Signal INT0 I/O IN Description Signal synchronized with commercial power source frequency. This is the basic timing for time processing of LSI. H : GND L : -5V 16.7 msec. 35 P07 OUT 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. 36 P06 OUT Key strobe signal. Signal applied to touch-key section.
Pin No. Signal NC I/O _ 52 Description Terminal not used. 53 XCOUT OUT Terminal not used. 54 XCIN Connected to VC. 55 NC IN _ 56 VCC IN Power source voltage: GND(0V). The power source voltage to drive LSI is input to VCC terminal. 57 OSCSEL IN Connected to VC(-5V). 58 XOUT OUT 59 VSS IN Power source voltage: -5.0V. The power source voltage to the LSI is input to VSS terminal. Connected to VC. Terminal not used. Internal clock oscillation output.
Pin No. Signal I/O Description 143 COM7 OUT Common data signal : COM9. Connected to LCD signal COM9. 144 COM6 OUT Common data signal : COM10. Connected to LCD signal COM10. ABSOLUTE HUMIDITY SENSOR CIRCUIT (1) Structure of Absolute Humidity Sensor The absolute 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.
TOUCH CONTROL PANEL SERVICING 1. Precautions for Handling Electronic Components This unit uses CMOS LSI in the integral part of the circuits. When handling these parts, the following precautions should be strictly followed. CMOS LSI have extremely high impedance at its input and output terminals. For this reason, it is easily influenced by the surrounding high voltage power source, static electricity charge in clothes, etc. and sometimes it is not fully protected by the built-in protection circuit.
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.. WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below before operating the oven. 1.
CAUTION: 1. DISCONNECT OVEN FROM POWER SUP PLY BEFORE REMOVING OUTER CASE. 2. DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING. NOTE: When replacing the outer case, the 2 special Torx screws must be reinstalled in the same locations. Special screw Screw Driver (Type: TORX T20 H or GTXH20-100) POWER TRANSFORMER REMOVAL Re-install 1. Rest transformer on the bottom plate with its primary terminals toward the oven face plate. 2.
OVEN LAMP AND LAMP SOCKET REMOVAL Disconnect the power supply cord and remove outer case. Open the door and block it open. Discharge high voltage capacitor. Remove the oven lamp from the oven lamp socket. Pull the wire leads from the oven lamp socket by pushing the terminal hole of the oven lamp socket with the small flat type screw driver. 6. Remove the oven lamp socket from the magnetron duct by turning the socket counterclockwise. 7. Remove the oven lamp from the socket by turning the oven lamp. 8.
COOLING FAN MOTOR REMOVAL REMOVAL 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. Disconnect the wire leads from the fan motor. 5. Remove the two (2) screws holding the fan motor to the oven cavity back plate. 6. Remove the fan blade from the fan motor shaft according to the following procedure. 7. Hold the edge of the rotor of the fan motor by using a pair of groove joint pliers.
3. Secure latch hook (with two (2) mounting screws) to oven flange. 4. Make sure that the monitor switch is operating properly and check continuity of the monitor circuit. Refer to chapter "Test Procedure" and Adjustment procedure. DOOR SENSING SWITCH/SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH ADJUSTMENT 1. Disconnect the power supply cord, and then remove outer case. 2. Open the door and block it open. 3. Discharge high voltage capacitor.
SEALER FILM 6. Re-install choke cover to door panel by pushing. Note: After any service to the door; (A) Make sure that door sensing switch and secondary interlock switch are operating properly. (Refer to chapter “Test Procedures”.). (B) An approved microwave survey meter should be used to assure compliance with proper microwave radiation emission limitation standards. After any service, make sure of the following : 1.
1 2 3 33 1 2 N.O. CN-A N.O. COM. T1 1 CN-B 2 4 B LU ORG CN-A 1 WHT CN-B 1 PNK 2 GRN 5 COM. WHT TURNTABLE MOTOR BRN WHT WHT RED ORG FAN MOTOR MAGNETRON POWER TRANSFORMER H.V. RECTIFIER HIGH VOLTAGE WIRE A HIGH VOLTAGE CAPACITOR HIGH VOLTAGE COMPONENTS NOTE: Hot (ORG) wire must be connected to the terminal with blue mark on the oven light socket. BLUE MARK ORG WHT 5 Figure S-1.
2 1 4 3 6 5 A A B B CN-C 12PIN LEAD WIRE HARNESS C Q2 2SB1238 b + – LED C2 GND + – C4 10µ/35v D2 D4 1SS270A C3 0.1µ/50v a 6 1SS270A C10 C R5 4.7k ZD1 HZ16-1 3 d D D1 D3 10G471K A2 4 C2 1000µ/35v 1 A1 VRS1 AC D6 C1 0.1µ/50v D1-D4 11ES1 T1 CN-A D5 R1 2.
C-3 C-5 BUZZERR NOTE AH SENSOR NC DOOR SENSING SWITCH NC C11 0.1µ/50v C10 47µ/16v CN-F D20 MA152WA LD10 LD11 LD12 LD13 LD15 LD14 G2 RICE G1 FRESH VEGETABLES 5 Frozen Entrees FROZEN VEGTABLES R91 3.32kD KEEP WARM 7 TIMER CLOCK 6 TOUCH START QUICK RECIPES LUNCH MENU BAKED POTATOES POWER LEVEL HELP MENU DEFROST 3 BREAKFAST MENU START 2 1 BEVERAGE FISH SEAFOOD 8 G5 G4 G3 G6 P02 P03 P23 P04 P21 P05 P20 R93 360kF P22 R92 1.
2 1 4 3 6 5 A A B B (CN - C) 1 12 1 2 4 E 5 6 ZD1 R1 B Q3 SP1 1 2 7 8 9 U C SH - A R2 D5 D6 SH - B B Q2 C5 D7 VRB D 2 E Q1 B R5 R4 3 R3 D8 R6 D CN - C 1 WH - 1 C4 C 1 9 E C3 CN - B D C2 RY2 P 11 C1 10 S D4 D2 D1 VRS1 T1 AC 1 VH D3 E F E 2 CN - A XA F F (J1) D9 OMIF D U (CN - D) (D10) G G AC RY1 OL FM TTM RY3 H H Figure S-5 Printed Wiring Board of Power Unit 1 2 4 3 36 5 6
2 1 4 3 6 5 OVEN AND CABINET PARTS 7-9 A A 7-9 7-6 2-3 B B 7-8 4-7 7-6 6-7 7-10 7-5 C 1-10 C 1-15 1-5 7-10 4-6 7-3 4-10 7-8 7-7 1-14 D D 7-7 1-9 7-7 4-2 4-8 7-4 E E 1-11 6-6 1-3 7-2 6-3 1-4 7-2 6-5 4-5 7-1 1-8 4-3 4-9 F F 1-12 1-13 7-10 2-1 6-4 1-7 1-8 7-1 4-4 1-6 4-1 G G 1-1 1-2 7-4 2-2 2-2 H H 4-11 2-2 7-4 2-2 1 2 7-4 4 3 37 5 6
1 2 4 3 6 5 CONTROL PANEL PARTS 3-1 A A 3-2 3-6 3-6 B B 3-3 3-6 C C 3-4 3-5 D D 5-4 DOOR PARTS E E 5-2 5-3 F F 5-1-1 MISCELLANEOUS 5-1-2 G G 6-1 6-2 H 6-9 H Actual wire harness may be different from illustration.
PARTS LIST ∆” may cause undue microwave exposure. Note: The parts marked “∆ The parts marked “*” are used in voltage more than 250V. REF. NO. PART NO.
REF. NO. PART NO.
PACKING AND ACCESSORIES TOP PAD ASSEMBLY DOOR PROTECTION SHEET PLASTIC BAG TRAY HOLDER 6-5 TURNTABLE TRAY 6-8 OPERATION MANUAL I O NT TH EO ITY AV C N VE BOTTOM PAD ASSEMBLY TRAY PACK PACKING CASE Non-replaceable items.
As product improvement is an ongoing process at DCS, we reserve the right to change specifications or design without notice. 5800 Skylab Road, Huntington Beach, CA. 92647 Tel: (714) 372-7000 Fax: (714) 372-7004 Parts/Customer Service (888) 281-5698 www.dcsappliances.com Part No. 17392 Rev.
