Viking DMOC205SS, VMOC205SS User Manual

SERVICE MANUAL

MICROWAVE OVEN

DMOC205SS VMOC205SS

S14M227DMO205

MODELS

DMOC205SS VMOC205SS

(VMOC205SS model shown)

In the interest of user-safety the oven should be restored to its original condition and only parts identical to those specified should be used.

WARNING TO SERVICE PERSONNEL: Microwave ovens contain circuitry capable of producing very high voltage and current. Contact with the following parts may result in a severe, possibly fatal, electrical shock. (Inverter unit that includes High Voltage Capacitor, High Voltage Power Transformer, High Voltage Rectifier and Heat sink etc., and Magnetron, High Voltage Harness etc..)

TABLE OF CONTENTS

Page PRECAUTIONS TO BE OBSERVED BEFORE AND DURING SERVICING TO

AVOID POSSIBLE EXPOSURE TO EXCESSIVE MICROWAVE ENERGY ................... INSIDE FRONT COVER

BEFORE SERVICING ...................................................................................................... INSIDE FRONT COVER

WARNING TO SERVICE PERSONNEL ................................................................................................................2

MICROWAVE MEASUREMENT PROCEDURE (Canada) ...................................................................................... 3

MICROWAVE MEASUREMENT PROCEDURE (USA) .......................................................................................... 4

FOREWORD AND WARNING ................................................................................................................................5

PRODUCT SPECIFICATIONS ............................................................................................................................... 6

GENERAL INFORMATION ...................................................................................................................................6

OPERATION .........................................................................................................................................................8

TROUBLESHOOTING GUIDE ............................................................................................................................. 14

TEST PROCEDURE ............................................................................................................................................16

TOUCH CONTROL PANEL ASSEMBLY .............................................................................................................23

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE .................................................................. 29

PICTORIAL DIAGRAM ........................................................................................................................................ 36

POWER UNIT CIRCUIT ....................................................................................................................................... 37

PRINTED WIRING BOARD ................................................................................................................................. 38

PARTS LIST ........................................................................................................................................................39

PACKING AND ACCESSORIES ......................................................................................................................... 44

Range Corporation

111 Front St., Greenwood, MS 38930

Tel: (888) 845-4641

This document has been published to be used for after sales service only. The contents are subject to change without notice.

DMOC205SS VMOC205SS

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. (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: (1) interlock operation, (2) proper door closing, (3) seal and sealing surfaces (arcing, wear, and other damage), (4) damage to or loosening of hinges and latches, (5) evidence of dropping or abuse.

compartments, check the magnetron, wave guide or transmission line, and cavity for proper alignment, integrity, and connections.

(d) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generation and

transmission systems shall be repaired, replaced, or adjusted by procedures described in this manual before the oven is released to the owner.

(e) A microwave leakage check to verify compliance with the Federal Performance Standard should be performed

on each oven prior to release to the owner.

BEFORE SERVICING

Before servicing an operative unit, perform a microwave emission check as per the Microwave Measurement Procedure outlined in this service manual. If microwave emissions level is in excess of the specified limit, contact Viking Service immediately @ 1-888-845-4641.

If the unit operates with the door open, service person should (1) tell the user not to operate the oven and (2) contact VIKING, plus the Department Of Health, Canada and/or the Food and Drug Administration's Center for Devices and Radiological Health immediately.

Service personnel should inform VIKING of any certified unit found with emissions in excess of 4mW/cm2. The owner of the unit should be instructed not to use the unit until the oven has been brought into compliance.

DANGER CAUTION

HIGH VOLTAGE

Do not energize a microwave oven with the outer case cabinet removed, because a microwave oven generates High Voltage in the circuit.

If you intend to operate the oven employing the high frequency switching power converter circuit, you should take special precautions to avoid an electrical shock hazard.

The high voltage transformer, high voltage capacitor and high voltage diode have energized high voltage potential approx. 8 KV.

The aluminium heat sink is connected to the switching power transistor Collector pole, and has an energized high voltage potential approx. 650V peak.

DO NOT ACCESS THE HIGH VOLTAGE TRANSFORMER, HIGH VOLTAGE CAPACITOR, HIGH VOLTAGE DIODE AND HEAT SINK WHEN THE POWER SUPPLY IS CONNECTED TO AN ELECTRICAL OUTLET.

Notes

DMOC205SS VMOC205SS

WARNING TO SERVICE PERSONNEL

Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts 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.

may result in a severe, possibly

Don't Touch ! Danger High Voltage

Before Servicing

1. Disconnect the power supply cord , and then remove outer case.

2. Open the door and block it open.

3. Discharge high voltage capacitor.

WARNING:RISK OF ELECTRIC SHOCK.

DISCHARGE THE HIGH-VOLTAGE CAPACITOR BEFORE SERVICING.

The high-voltage capacitor remains charged about 60 seconds after the oven has been switched off. Wait for 60 seconds and then short-circuit the connection of the high-voltage capacitor (that is the connecting lead of the high-voltage rectifier) against the chassis with the use of an insulated screwdriver.

Whenever troubleshooting is performed the power supply must be disconnected. It may in, some cases, be necessary to connect the power supply after the outer case has been removed, in this event,

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 leads to the primary of the power transformer.

5. Ensure that the leads remain isolated from other components and oven chassis by using insulation tape.

6. After that procedure, reconnect the power supply cord.

When the testing is completed,

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. Reconnect the leads to the primary of the power transformer.

5. Reinstall the outer case (cabinet).

6. Reconnect the power supply cord after the outer case is installed.

7. Run the oven and check all functions.

After repairing

1. Reconnect all leads removed from components during testing.

2. Reinstall the outer case (cabinet).

3. Reconnect the power supply cord after the outer case is installed.

4. Run the oven and check all functions.

Microwave ovens should not be run empty. To test for the presence of microwave energy within a cavity, place a cup of cold water on the oven turntable, close the door and set the power to HIGH and set the microwave timer for two (2) minutes. When the two minutes has elapsed (timer at zero) carefully check that the water is now hot. If the water remains cold carry out Before Servicing procedure and re- examine the connections to the component being tested.

When all service work is completed and the oven is fully assembled, the microwave power output should be checked and a microwave leakage test should be carried out.

DMOC205SS VMOC205SS

MICROWAVE MEASUREMENT PROCEDURE (CANADA)

After adjustment of the door switches are completed individually or collectively, switch test and microwave leakage test must be performed with survey instrument and test result must be confirmed to meet the requirement of the performance standard for microwave ovens as undermentioned.

A. Requirements:

Every microwave oven shall function in such a manner that when the oven is fully assembled and operating with its service controls and user controls adjusted to yield the maximum output, the leakage radiation, at all points at least 5 cm. from

the

external surface of the oven, does not exceed:

1) 1.0mW/cm2 with the test load of 275 ± 15 ml of water at an initial temperature 20 ±5oC.

2) 5.0mW/cm

3) 5.0mW/cm

when the outer enclosure is removed with a test load of 275 ± 15 ml of water at an initial temperature 20±5oC.

without a test load.

B. Preparation for testing: Before beginning the actual measurement of leakage, proceed as follows:

1) Make sure that the actual instrument is operating normally as specified in its instruction booklet. Important: Survey instruments that comply with the requirement for instrumentation as prescribed by CSA and NHW performance standard for microwave ovens must be used for testing recommended instruments are , NARDA 8100 and NARDA 8200.

2) Place the oven tray in the oven cavity.

3) Place the load of 275±15 ml of tap water initially at 20±5oC in the center of the oven cavity. The water container shall be a low form of 600 ml beaker with an inside diameter of approx. 8.5 cm (3-1/2 in.) and made of an electrically nonconductive material such as glass or plastic. The placing of this standard load in the oven is important not only to protect the oven, but also to insure that any leakage is measured accurately.

4) Set the cooking control on Full Power Cooking Mode, Close the door and select a cook cycle of several minutes. If the water begins to boil before the survey is completed, replace it with 275 ml of cool water.

C. Leakage test with enclosure installed :

1) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and the body of the oven.

2) Move the probe slowly, not faster than 2.5 cm/sec. along the gap, watching for the maximum indication on the meter.

3) Check for leakage at the door screen, sheet metal seams and other accessible positions where the continuity of the metal has been breached (eg., around the switches, indicator, and vents). While testing for leakage around the door pull the door away from the front of the oven as far as is permitted by the closed latch assembly.

4) Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than 4mW/cm2, and that the secondary interlock switch does turn the oven OFF before any door movement.

C. Leakage test without enclosure:

1) Remove the enclosure (cabinet).

2) Grasp the probe of the survey instrument and hold it perpendicular to all mechanical and electric parts of the oven that is accessible to the user of the oven including, but not limited to, the waveguide, cavity seams, magnetron gap between the door and the body of the oven.

3) Move the probe slowly, not faster than 2.5 cm/sec. along the gap, watching for the maximum indication on the meter.

4) Measure carefully at the point of highest leakage and make sure that the highest leakage is under 5mW/cm2.

CAUTION: Special attention should be given to avoid electrical shock because HIGH VOLTAGE is generated during this

test

No Load test

1) Operate the oven without a load and measure the leakage by the same method as the above test procedure " Leakage test with enclosure installed"

2. Make sure that the highest leakage should not exceed 5mW/cm2.

NOTE: After servicing, record data on service invoice and microwave leakage report.

DMOC205SS VMOC205SS

MICROWAVE MEASUREMENT PROCEDURE (USA)

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/cm surface of the oven.

2) Safety interlock switches: Primary interlock relay switch shall prevent microwave radiation emission in excess of the requirement as above mentioned. Secondary interlock relay and door sensing switch shall prevent microwave radiation emission in excess of 5 mW/cm2 at any point 5cm or more from the external surface of the oven.

B. Preparation for testing: Before beginning the actual measurement of leakage, proceed as follows:

1) Make sure that the actual instrument is operating normally as specified in its instruction booklet.

Important: Survey instruments that comply with the requirement for instrumentation as prescribed by the performance standard for microwave ovens, 21 CFR 1030.10(c)(3)(i), must be used for testing.

2) Place the oven tray in the oven cavity.

3) Place the load of 275±15 ml (9.8 oz) of tap water initially at 20±5

C (68OF) in the center of the oven cavity. The water container shall be a low form of 600 ml (20 oz) beaker with an inside diameter of approx. 8.5 cm (3-1/2 in.) and made of an electrically nonconductive material such as glass or plastic. The placing of this standard load in the oven is important not only to protect the oven, but also to insure that any leakage is measured accurately.

4) Set the cooking control on Full Power Cooking Mode.

5) Close the door and select a cook cycle of several minutes. If the water begins to boil before the survey is completed, replace it with 275 ml of cool water.

at any point 5cm or more from the external

C. Leakage test:

Closed-door leakage test (microwave measurement):

1) Grasp the probe of the survey instrument and hold it perpendicular to the gap between the door and the body of the oven.

2) Move the probe slowly, not faster than 1 in./sec. (2.5 cm/sec.) along the gap, watching for the maximum indication on the meter.

3) Check for leakage at the door screen, sheet metal seams and other accessible positions where the continuity of the metal has been breached (eg., around the switches, indicator, and vents). While testing for leakage around the door, pull the door away from the front of the oven as far as is permitted by the closed latch assembly.

4) Measure carefully at the point of highest leakage and make sure that the highest leakage is no greater than 4mW/cm2, and that the primary interlock switch/secondary interlock relay does turn the oven OFF before any door movement.

NOTE: After servicing, record data on service invoice and microwave leakage report.

SERVICE MANUAL

VIKING RANGE CORPORATION

MICROWAVE OVENS

DMOC205SS VMOC205SS

FOREWORD

PRODUCT DESCRIPTION

GENERAL INFORMATION

DMOC205SS VMOC205SS

This Manual has been prepared to provide Viking Service Personnel with Operation and Service Information for the Viking Microwave Ovens, DMOC205SS, VMOC205SS.

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.

Check the interlock switches and the door seal carefully. Special attention should be given to avoid electrical shock and microwave radiation hazard.

WARNING

Never operate the oven until the following points are ensured: (A) The door is tightly closed. (B) The door brackets and hinges are not defective. (C) The door packing is not damaged. (D) The door is not deformed or warped. (E) There is no other visible damage with the oven.

Servicing and repair work must be carried out only by trained service personnel.

DANGER

Certain initial parts are intentionally not grounded and present a risk of electrical shock only during servicing. Service personnel

- Do not contact the following parts while the appliance is energized; High Voltage Capacitor, Power Transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage Harness; If provided, Vent Hood, Fan assembly, Cooling Fan Motor.

OPERATION

TROUBLESHOOTING GUIDE AND TEST PROCEDURE

TOUCH CONTROL PANEL

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE

WIRING DIAGRAM

PARTS LIST

All the parts marked “*” on parts list are used at voltages more than 250V.

Removal of the outer wrap gives access to voltage above 250V.

All the parts marked “∆” on parts list may cause undue microwave exposure, by themselves, or when they are damaged, loosened or removed.

VIKING RANGE CORPORATION

111 Front St., Greenwood, MS 38930

Tel: (888) 845-4641

DMOC205SS VMOC205SS

SPECIFICATION

ITEM DESCRIPTION

Power Requirements 120 Volts

13.0 Amperes (Microwave) / 13.0 Amperes (Convection)

60 Hertz / Single phase, 3 wire grounded

Power Output 900 watts (IEC 705 Test Procedure)

Operating frequency of 2450MHz

Convection Power Output 1450 Watts

Case Dimensions Width 24-5/8" Height 14-7/8" Depth 19-1/8"

Cooking Cavity Dimensions (1.5 Cubic Feet ) Width 16-1/8" Height 9-5/8" Depth 16-1/8"

Control Complement Touch Control System

Timer (0 - 99 min. 99 seconds)

Microwave Power for Variable Cooking

Repetition Rate;

P-HI ..........................................Full power throughout the cooking time

P-90 ............................................................ approx. 90% of Full Power

P-80 ............................................................ approx. 80% of Full Power

P-70 ............................................................ approx. 70% of Full Power

P-60 ............................................................ approx. 60% of Full Power

P-50 ............................................................ approx. 50% of Full Power

P-40 ............................................................. approx. 40% of Full Power

P-30 ............................................................. approx. 30% of Full Power

P-20 ............................................................ approx. 20% of Full Power

P-10 ............................................................. approx. 10% of Full Power

P-0 ............................................. No power throughout the cooking time

Convection Temperature for Variable Cooking

CONVECTION .............................................. 100 - 450οF Temp. control

LOW MIX. BAKE .............................. 350οF with 10% microwave power

HIGH MIX. ROAST ........................... 300οF with 30% microwave power

SLOW COOK ........................................ 300οF for 4 hours (no preheat)

BROIL............................................................................ 450οF (preheat)

Help pad, Reheat pad, Add-A-Minute pad, Popcorn pad Defrost pad, Sensor Cook pad, Convec Broil pad Convec Roast pad, Convec Bake pad, Convec pad Broil pad, Slow Cook pad, Preheat pad. Number and temperature selection pads, Timer pad, Clock pad Stop/Clear pad, Power Level pad, Start / Touch On pad

Oven Cavity Light Yes

Safety Standard UL Listed FCC Authorized

DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J Canadian Standards Association. Health CANADA, Industry CANADA.

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 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.

DMOC205SS VMOC205SS

Electrical Requirements The electrical requirements are a 115 -120 volt 60 Hz, AC only, 15 or more amp. fused electrical supply. It is recommended that a

3-Pronged Plug

Grounded Receptacle Box

separate circuit serving only this appliance be provided. When installing this appliance, observe all applicable codes and ordinances. A short power-supply cord is provided to reduce risks of becoming entangled in or tripping over a longer cord. Where a two-pronged wall-receptacle is encountered, it is the personal responsibility and obligation of the customer to contact a qualified

Grounding Pin

electrician and have it replaced with a properly grounded three-pronged wall receptacle or have a grounding adapter properly grounded and polarized. If an extension cord must be used, it should be a 3-wire, 15

3-Pronged Receptacle

amp. or more 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.

OVEN DIAGRAM

11 6

TOUCH CONTROL PANEL

1. Ventilation openings. (Rear side)

2. Oven door with see-through window.

3. Oven lamp.

4. Turntable support.

5. Removable turntable. The turntable will rotate clockwise or counterclockwise.

6. Safety door latches. The oven will not operate unless the door is securely closed.

7. Wave guide cover.

8. Door open button.

9. Auto-Touch control panel.

10. Lighted digital display.

11. Convection air openings.

12. Removable low rack. (Broiling trivet)

13. Removable low rack. (Baking rack)

14. Turntable motor shaft.

15. Power supply cord.

VMOC205SS

DMOC205SS VMOC205SS

OPERATION

DESCRIPTION OF OPERATING SEQUENCE

The following is a description of component functions during oven operation.

OFF CONDITION

Closing the door activates the door sensing switch and secondary interlock switch. (In this condition, the monitor switch contacts are opened.) When oven is plugged in, 117 volts A.C. is supplied to the control unit. (Figure O-1).

1. The display will show "WELCOME, PRESS CLEAR". To set any program or set the clock, you must first touch the STOP/CLEAR pad. The display will clear, and " : " will appear.

NOTE: When the door is opened, the oven lamp comes on.

2. A signal is input to the control unit, energizing the coil of shut-off relay (RY-4). RY4 contacts close, completing a circuit to the damper motor. The damper motor now operates moving the damper to the open position, thereby closing the contacts of the damper switch inputs a signal to the control unit. The coil of relay RY4 is de-energized, opening its contacts, thereby turning off the damper motor.

COOKING CONDITION

Program desired cooking time Variable Cooking Control by touching the NUMBER pads and the power level pad. When the START pad is touched, the following operations occur:

1. The contacts of relays are closed and components connected to the relays are turned on as follows. (For details, refer to Figure O-2)

RELAY CONNECTED COMPONENTS

RY-1 Oven lamp/Turntable motor

RY-2 Power transformer

RY-3 Heating element

RY-4 Damper motor

RY-5 Convevtion motor

RY-6 Fan motor

2. 117 volts A.C. is supplied to the primary winding of the power transformer and is converted to about 3 volts A.C. output on the filament winding, and approximately 2360 volts A.C. on the high voltage winding.

3. The filament winding voltage heats the magnetron filament and the H.V. winding voltage is sent to a voltage doubler circuit.

4. The microwave energy produced by the magnetron is channelled through the waveguide into the cavity feedbox, and then into the cavity where the food is placed to be cooked.

5. Upon completion of the cooking time, the power transformer, oven lamp, etc. are turned off, and the generation of microwave energy is stopped. The oven will revert to the OFF condition.

6. When the door is opened during a cook cycle, third door switch, monitor switch, door sensing switch, the secondary interlock relay and the primary interlock

switch are activated with the following results. The circuits to the turntable motor, the cooling fan motor, and the high voltage components are de-energized, the oven lamp remains on, and the digital read-out displays the time still remaining in the cook cycle when the door was opened.

7. The monitor switch is electrically monitoring the operation of the relay (RY1) and the primary interlock switch and is mechanically associated with the door so that it will function in the following sequence.

(1) When the door opens from a closed position, the door

sensing switch and the primary interlock switch open their contacts, and then the monitor switch contacts close and then the third door switch contacts open.

(2) When the door is closed from the open position, the

monitor switch contacts open and the third door switch contacts close first, and then the contacts of the primary interlock switch and the door sensing switch close.

If the relay (RY1) and the primary interlock switch fail with their contacts closed when the door is opened, the closing of the monitor switch contacts will form a short circuit through the monitor fuse, the relay (RY1) and the primary interlock switch, causing the monitor fuse to blow.

POWER LEVEL P-0 TO P-90 COOKING

When Variable Cooking Power is programmed, the 117 volts A.C. is supplied to the power transformer intermittently through the contacts of relay (RY-2). RY-2 is operated by the control unit within an varying time base. Microwave power operation is as follows:

VARI-MODE ON TIME OFF TIME Power 10(P-HI) 32 sec. 0 sec.

(100% power) Power 9(P-90) 30 sec. 2 sec.

(approx. 90% power) Power 8(P-80) 26 sec. 6 sec.

(approx. 80% power) Power 7(P-70) 24 sec. 8 sec. (approx. 70% power)

Power 6(P-60) 22 sec. 10 sec. (approx. 60% power)

Power 5(P-50) 18 sec. 14 sec. (approx. 50% power)

Power 4(P-40) 16 sec. 16 sec. (approx. 40% power)

Power 3(P-30) 12 sec. 20 sec. (approx. 30% power)

Power 2(P-20) 8 sec. 24 sec. (approx. 20% power)

Power 1(P-10) 6 sec. 26 sec. (approx. 10% power)

Power 0(P-0) 0 sec. 32 sec. (0% power)

Note: The ON/OFF time ratio does not correspond with

the percentage of microwave power, because approx. 2 seconds are needed for heating of the magnetron filament.

DMOC205SS

12 SEC. 20 SEC.

32 SEC.

LOW MIX

BAKE

HIGH MIX

ROAST

MICROWAVE POWER

= APPROX. 30%

CONVECTION

TEMPERATUE

= 300°F

MICROWAVE POWER

= APPROX. 10%

CONVECTION

TEMPERATUE

= 350°F (180°C)

26 SEC.6 SEC.

OFF

(MICRO.)

(CONVEC.)

(MICRO.)

(CONVEC.)

VMOC205SS

CONVECTION COOKING CONDITION

PREHEATING CONDITION

Program desired convection temperature by touching the CONVECTION pad and the Temperature pad. When the START pad is touched, the following operations occur:

1. The coil of shut-off relays (RY1, RY3,RY5 and RY6) are energized, the oven lamp, cooling fan motor, turntable motor and convection motor are turned on.

2. The coil of relay (RY4) is energized by the control unit. The damper is moved to the closed position, opening the damper switch contacts. The opening of the damper switch contacts sends a signal to the LSI on the control unit de-energizing the relay (RY4) and opening the circuit to the damper motor.

3. The coil of heater relay (RY3) is energized by the control unit and the main supply voltage is applied to the heating element.

4. When the oven temperature reaches the selected preheat temperature, the following operations occur: 4-1 The heater relay is de-energized by the control unit

temperature circuit and thermistor, opening the circuit to the heating element.

4-2. The oven will continue to function for 30 minutes,

turning the heater on and off, as needed to maintain the selected preheat temperature. The oven will shut-down completely after 30 minutes

CONVECTION COOKING CONDITION

When the preheat temperature is reached, a beep signal will sound indicating that the holding temperature has been reached in the oven cavity. Open the door and place the food to be cooked in the oven. Touch the CONVEC pad first and then touch the Temperature pad. And program desired cooking time by touching the Number pads. When the START pad is touched, the following operations occur:

1. The numbers on the digital read-out start to count down to zero.

2. The oven lamp, turntable motor, cooling fan motor and convection motor are energized.

3. Heater relay (RY3) is energized (if the cavity temperature is lower than the selected temperature) and the main supply voltage is applied to the heating element to return to the selected cooking temperature.

4. Upon completion of the cooking time, the audible signal will sound, and oven lamp, turntable motor, cooling fan motor and convection motor are de-energized. At the end of the convection cycle, if the cavity air temperature is above 275οF, the circuit to RY6 will be maintained (by the thermistor circuit) to continue operation of the cooling fan motor until the temperature drops below 245οF, at which time the relay will be de-energized, turning off the fan motor. Relay RY5 will however, open as soon as the convection cycle has ended, turning off the convection fan motor.

5. At the end of the convection cook cycle, shut-off relay (RY4) is energized turning on the damper motor. The damper is returned to the open position, closing the damper switch contacts which send a signal to the control unit, de-energizing shut-off relay (RY4).

AUTOMATIC MIX COOKING CONDITION

Touch the HIGH MIX/ROAST or the LOW MIX/BAKE pad

first. And then program desired cooking time by touching the Number pads. The LOW MIX/BAKE pad is preprogrammed for 350

F with 10% microwave power, while the HIGH MIX/ROAST pad is preprogrammed for 300οF with 30% microwave power. When the START pad is touched, the following operations occur:

1. The numbers on the digital read-out start to count down

to zero.

2. The shut-off relays (RY1,RY2,RY3,RY5 and RY6) are

energized, turning on the oven lamp, turntable motor, cooling fan motor and convection fan motor.

3. The shut-off relay (RY4) is energized.

The damper door is closed from the open position.

4. The heater relay (RY3) is energized, applying the main

supply voltage to the heating element.

5. Now, the oven is in the convection cooking condition.

6. When the oven temperature reaches the selected

temperature, the following operations occur: 6-1. The power supply voltage is alternated to the

heating element and power transformer.

6-2. The heating element operates through the heater

relay (RY3) contacts and the power transformer operates through the primary interlock relay (RY2) contacts.

6-3. These are operated by the control unit to supply

alternately within a 32 second time base, convection heat and microwave energy.

The relationship between the convection and microwave power operations are as follows.

Note: The ON and OFF time ratio does not correspond

with the percentage of microwave power, because approx. 2 seconds are needed for heating of the magnetron filament.

Note: During alternate Microwave/Convection operation,

the convection heater is energized only if the cavity temperature drops below the set temperature.

SENSOR COOKING CONDITION

Using the SENSOR COOK function, the foods are cooked without figuring time, power level or quantity. When the oven senses enough steam from the food, it relays the information to its microprocessor which will calculate the remaining cooking time and power level needed for best results. When the food is cooked, water vapor is developed.

DMOC205SS VMOC205SS

The sensor “senses” the vapor and its resistance increases gradually. When the resistance reaches the value set according to the menu, supplementary cooking is started. The time of supplementary cooking is determined by experiment with each food category and inputted into the LSI. An example of how sensor works:

1. Potatoes at room temperature.

Vapor is emitted very slowly.

ICROW

AVE

2. Heat potatoes. Moisture and humidity is emitted rapidly. You can smell the aroma as it cooks.

3. Sensor detects moisture and

AH SENSOR

ICROW

AVE

humidity and calculates cooking time and variable power.

Cooking Sequence.

1. Touch SENSOR COOK pad.

NOTE: The oven should not be operated on SENSOR

COOK immediately after plugging in the unit. Wait two minutes before cooking on SENSOR COOK.

2. Select desired Sensor setting.

3. Touch START pad. The coil of shut-off relay (RY1, RY6) is energized, the oven lamp and cooling fan motor are turned on, but the power transformer is not turned on.

4. 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.

NOTE: During this first stage, do not open the door or

touch STOP/CLEAR pad.

5. When the sensor detects the vapor emitted from the food, the display switches over to the remaining cooking time and the timer counts down to zero. At this time, the door may be opened to stir food, turn it or season, etc.

6. When the timer reaches zero, an audible signal sounds. The shut-off relay and cook relay are de-energized and the power transformer, oven lamp, etc. are turned off.

7. Opening the door or touching the STOP/CLEAR pad, the time of day will reappear on the display and the oven will revert to an OFF condition.

COMPU BROIL/ COMPU ROAST/ COMPU BAKE

COMPU BROIL/ ROAST/ BAKE will automatically compute the oven temperature, microwave power and cooking time for baking, roasting and broiling. Set the desired program by touching the COMPU BROIL/ ROAST/ BAKE pad, and number pad. Enter the weight by touching the Number pads. When the START pad is touched, the following operations occur:

1. The COOK indicator will light and the Convection Fan Symbol will rotate.

2. The cooking time will appear on the display and start counting down to zero. The cooking time is adjusted automatically according to the weight of the food.

3. The shut-off relays (RY1, RY5 and RY6) are energized, turning on the oven lamp, turntable motor, cooling fan motor and convection motor. The power supply voltage is applied to the heating element.

4. Now, the oven is in the convection cooking mode.

5. When the oven temperature has reached the programmed convection temperature, the oven goes into the programmed cooking mode.

6. At the end of the COMPU BROIL/ ROAST/ BAKE cycle, the damper is returned to the open position and the oven will go to the off condition. The cooling fan will remain on until the oven has cooled.

COMPU DEFROST COOKING

The COMPU DEFROST key is a special function key to defrost meats and poultry faster and better. COMPU DEFROST automatically defrosts roast beef, etc.. When the COMPU DEFROST is selected and the food weight is entered by using the COMPU DEFROST pad, the oven will cook according to the special cooking sequence.

FIRE SENSING FEATURE (MICROWAVE MODE)

This model incorporates a sensing feature which will stop the oven's operation if there is a fire in the oven cavity during microwave cooking. This is accomplished by the LSI repeatedly measuring the voltage across the temperature measurement circuit (thermistor) during it's 32-seconds time base comparing the obtained voltage measurements. If the most recent voltage measured is 300mV greater than the previous voltage measured, the LSI judges it as a fire in the oven cavity and switches off the relays to the power transformer, fan motor and convection motor. The LSI also stops counting down and closes the damper door so that no fresh air will enter the oven cavity. Please refer to the following section for a more detailed description.

Operation

Please refer to the timing diagrams below.

1. The thermistor operates within a 32-seconds time base and it is energized for three (3) seconds and off for 29 seconds. Two (2) seconds after the thermistor is energized, the voltage across the temperature measurement circuit is sampled by the LSI and twenty one (21) seconds after the thermistor is cut off the LSI turns on the cooling fan for six (6) seconds.

2. The above procedure is repeated. If the difference between the first voltage measured (in step 1) and the voltage measured when the procedure is repeated (step

2) is greater than 300mV the LSI makes the judgment that there is a fire in the oven cavity and will switch off the relays to the power transformer, fan motor and convection motor. The LSI also stops counting down and closes the damper door so that no fresh air will enter the oven cavity.

3. Once the fire sensor feature has shut the unit down, the programmed cooking cycle may be resumed by pressing the "START" pad or the unit may be reset by pressing the "CLEAR" pad.

CONVECTION

MOTOR

THERMISTOR

Sensing

Voltage

0 2 3 24 30 32 (sec.) 64 (sec.)

OFF

3 sec.

OFF

Sensing the voltage across temperature measurement circuit.

6 sec.

DMOC205SS VMOC205SS

IMPORTANT: During sensor cooking operation, the fire sensing operation sequence will not begin until the AH sensor has

SCHEMATIC DIAGRAM

NOTE: CONDITION OF OVEN

1. DOOR CLOSED.

2. CLOCK APPEARS ON DISPLAY.

FUSE

117V 60Hz

SCHEMATIC

NOISE FILTER

0.0033µ/AC125V

NOISE SUPPRESSION COIL

0.022µ/AC250V

0.0033µ/AC125V

OVEN LAMP

THIRD DOOR SWITCH

CONV. THERMAL CUT-OUT

TTM

TURNTABLE MOTOR

CONVECTION MOTOR

FAN MOTOR

DAMPER MOTOR

MAGNETRON THERMAL CUT-OUT

A-7

A-9

DOOR SENSING SWITCH

OVEN THERMAL CUT-OUT

RY4

CONTROL UNIT

THERMISTOR

detected vapors and initiated a sensor cooking cycle. This is because the operation of the convection fan would interfere with the AH sensor's vapor detection.

COM.

RY6

RY2

F-3 F-2

(RY1)

RY1

SECONDARY INTERLOCK RERAY

AH SENSOR

F-1

N.O. (RY1)

COM. (RY3)

COM. (RY2)

N.O. (RY2)

N.O. (RY3)

POWER TRANSFORMER

PRIMARY INTERLOCK SWITCH

CAPACITOR

0.94µ

MONITOR SWITCH

HEATIMG ELEMENT

RY5

RY3

E-5E-4E-3E-2E-1

E-6

DAMPER SWITCH

MAGNETRON

H.V. RECTIFIER

NOTE: CONDITION OF OVEN

SCHEMATIC

1. DOOR CLOSED.

2. COOKING TIME PROGRAMMED.

3. “START” PAD TOUCHED.

CONV. THERMAL CUT-OUT

TTM

TURNTABLE MOTOR

OVEN LAMP

117V 60Hz

NOISE FILTER

FUSE

NOISE SUPPRESSION COIL

0.0033µ/AC125V0.0033µ/AC125V

0.022µ/AC250V

THIRD DOOR SWITCH

Figure O-1. Oven Schematic-OFF Condition

CONVECTION MOTOR

FAN MOTOR

DAMPER MOTOR

MAGNETRON THERMAL CUT-OUT

A-7

A-9

DOOR SENSING SWITCH

OVEN THERMAL CUT-OUT

RY4

CONTROL UNIT

THERMISTOR

RY5

RY3

E-6

E-5E-4E-3E-2E-1

DAMPER SWITCH

RY6

RY2

F-3 F-2

COM. (RY1)

RY1

SECONDARY INTERLOCK RERAY

AH SENSOR

F-1

N.O. (RY1)

COM. (RY3)

COM. (RY2)

N.O. (RY2)

N.O. (RY3)

POWER TRANSFORMER

PRIMARY INTERLOCK SWITCH

CAPACITOR

0.94µ

MONITOR SWITCH

HEATIMG ELEMENT

MAGNETRON

H.V. RECTIFIER

Figure O-2. Oven Schematic-Microwave Cooking Condition

DMOC205SS VMOC205SS

NOTE: CONDITION OF OVEN

SCHEMATIC

1. DOOR CLOSED.

2. MIX COOKING PAD TOUCHED.

3. COOKING TIME PROGRAMMED.

4. “START” PAD TOUCHED.

5. RY2 AND RY3 WILL ALTERNATELY CLOSE. DURING COOK CYCLE.

117V 60Hz

NOISE FILTER

FUSE

NOISE SUPPRESSION COIL

0.0033µ/AC125V0.0033µ/AC125V

0.022µ/AC250V

THIRD DOOR SWITCH

CONV. THERMAL CUT-OUT

TTM

TURNTABLE MOTOR

OVEN LAMP

FAN MOTOR

MAGNETRON THERMAL CUT-OUT

CONVECTION MOTOR

DAMPER MOTOR

A-7

A-9

DOOR SENSING SWITCH

OVEN THERMAL CUT-OUT

RY4

CONTROL UNIT

THERMISTOR

RY5

RY3

E-5E-4E-3E-2E-1

E-6

DAMPER SWITCH

RY6

RY2

F-3 F-2

COM. (RY1)

RY1

SECONDARY INTERLOCK RERAY

AH SENSOR

F-1

N.O. (RY1)

COM. (RY3)

COM. (RY2)

N.O. (RY2)

N.O. (RY3)

POWER TRANSFORMER

PRIMARY INTERLOCK SWITCH

CAPACITOR

0.94µ

MONITOR SWITCH

HEATIMG ELEMENT

MAGNETRON

H.V. RECTIFIER

Figure O-3. Oven Schematic-Automatic Mix Cooking Condition

NOTE: CONDITION OF OVEN

1. DOOR CLOSED.

2. CONVECTION PAD TOUCHED.

3. DESIRED TEMP. TOUCHED.

4. COOKING TIME PROGRAMMED.

5. “START” PAD TOUCHED.

FUSE

117V 60Hz

SCHEMATIC

NOISE FILTER

0.0033µ/AC125V0.0033µ/AC125V

NOISE SUPPRESSION COIL

0.022µ/AC250V

OVEN LAMP

THIRD DOOR SWITCH

TTM

TURNTABLE MOTOR

CONV. THERMAL CUT-OUT

CONVECTION MOTOR

FAN MOTOR

MAGNETRON THERMAL CUT-OUT

DAMPER MOTOR

A-7

A-9

DOOR SENSING SWITCH

OVEN THERMAL CUT-OUT

RY4

CONTROL UNIT

THERMISTOR

RY5

RY3

E-5E-4E-3E-2E-1

E-6

DAMPER SWITCH

RY6

RY2

F-3 F-2

COM. (RY1)

RY1

SECONDARY INTERLOCK RERAY

AH SENSOR

F-1

N.O. (RY1)

COM. (RY3)

COM. (RY2)

N.O. (RY2)

N.O. (RY3)

POWER TRANSFORMER

PRIMARY INTERLOCK SWITCH

CAPACITOR

0.94µ

MONITOR SWITCH

HEATIMG ELEMENT

MAGNETRON

H.V. RECTIFIER

Figure O-4. Oven Schematic-Convection Cooking Condition

DESCRIPTION AND FUNCTION OF COMPONENTS

DMOC205SS VMOC205SS

DOOR SENSING AND PRIMARY INTERLOCK SWITCHES

The door sensing switch in the secondary interlock system is mounted in the upper position on the latch hook, the primary interlock switch is mounted in the lower position on the latch hook. They are activated by the latch heads on the door. When the door is opened, the switches interrupt the circuit to all components. A cook cycle cannot take place until the door is firmly closed thereby activating both interlock switches. The secondary interlock system consists of the door sensing switch and secondary interlock relay located on the control circuit board.

LATCH HOOK

THIRD DOOR SWITCH

DOOR SENSING SWITCH

LATCH HEADS

DOOR OPEN BUTTON

MONITOR SWITCH

PRIMARY INTERLOCK SWITCH

SWITCH LEVER

OPEN LEVER

Figure D-1. Door sensing switch, monitor switch, third

door switch and primary interlock switch

MONITOR SWITCH

The monitor switch is mounted on the middle position of latch hook. It is activated (the contacts opened) by the lower latch head while the door is closed. The switch is intended to render the oven inoperative by means of blowing the monitor fuse when the contacts of the relay RY1 and primary interlock switch fail to open when the door is opened.

Functions:

1. When the door is opened, the monitor switch contact

close (to the ON condition) due to their being normally closed. At this time the door sensing and primary interlock and third door switches are in the OFF condition (contacts open) due to their being normally open contact switches.

2. As the door goes to a closed position, the monitor

switch contacts are first opened and then the door sensing switch, third door switch and the primary interlock switch contacts close. (On opening the door, each of these switches operate inversely.)

3. If the door is opened, and the relay RY1 and the primary

interlock switch contacts fail to 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 SWITCH, RELAY(RY1) AND MONITOR SWITCH FOR PROPER OPERATION. (REFER TO CHAPTER “TEST PROCEDURE”).

NOTE: MONITOR FUSE AND MONITOR SWITCH ARE

REPLACED AS AN ASSEMBLY.

THIRD DOOR SWITCH

The switch is activated by the latch heads, while the door is closed. When the door is opened, the switch interrupt the circuit to the power transformer. This switch prevents power transformer engaging and microwave when the door opened.

THERMISTOR

The thermistor is a negative temperature coefficient type. The temperature in the oven cavity is detected through the resistance of the thermistor, and then the control unit causes the heater relay to operate, thus the current to the heating element is turned ON/OFF.

MAGNETRON THERMAL CUT-OUT

The thermal cut-out located on the waveguide is designed to prevent damage to the magnetron if an over heated condition develops in the magnetron due to cooling fan failure, obstructed air guide, dirty or blocked air intake, etc. Under normal operation, the thermal cut-out remains closed. However, when abnormally high temperatures are reached within the magnetron, the thermal cut-out will open at 257οF (125οC) causing the oven to shut down. magnetron thermal cut-out is not reset at room temperature.

OVEN THERMAL CUT-OUT

The thermal cut-out located on the side of the steam duct is designed to prevent damage to the unit if the foods in the oven catch fire due to over heating produced by improper setting of cooking time or failure of control unit. Under normal operation, the thermal cut-out remains closed. However, when abnormally high temperatures are reached within the oven cavity, the thermal cut-out will open at 302οF (150οC) causing the oven to shut down. When the thermal cut-out has cooled, the thermal cut-out closes at 266οF (130οC)

CONV. THERMAL CUT-OUT

The thermal cut-out located on the left side of the thermal protection plate (left) is designed to prevent damage to the heater unit if an over heated condition develops in the tube due to cooling fan failure, obstructed air ducts, dirty or blocked air intake, etc. Under normal operation, the thermal cut-out remains closed. However, when abnormally high temperatures are reached within the heater unit, the thermal cut-out will open at 302οF (150οC) causing the oven to shut down. When the thermal cut-out has cooled, the thermal cut-out closes at 266οF (130οC)

HEATING ELEMENT

The heating element is located at the left side of the oven cavity. It is intended to heat air driven by the convection fan. The heated air is kept in the oven and force-circulated and reheated by the heating element.

CONVECTION COOKING SYSTEM

This oven is designed with a hot air heating system where food is not directly heated by the heating element, but is heated by forced circulation of the hot air produced by the heating element. The air heated by the heating element is circulated through the convection passage provided on the outer casing of the

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