Viking DMOC205SS Absolute Humidity Sensor Circuit, Structure of Absolute Humidity Sensor

Page 29

DMOC205SS

VMOC205SS

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. Each sensor is provided with the protective cover made of metal mesh to be protected from the external airflow.

 

 

Sensing part

Sensing part

 

Sensing part

(Open vessel)

(Closed vessel)

 

 

 

 

(Open vessel)

Thermistor

Thermistor

Ventilation

 

element

element

openings

Sensing part

 

Sensor

 

(Closed vessel)

 

case

View of sensor case removed

Cross section view

 

(2)Operational Principle of Absolute Humidity Sensor The figure below shows the basic structure of an absolute humidity sensor. A bridge circuit is formed by two thermistors and two resistors (R1 and R2).

The output of the bridge circuit is to be amplified by the operational amplifier.

Each thermistor is supplied with a current to keep it heated at about 150οC (302οF), the resultant heat is dissipated in the air and if the two thermistors are placed in different humidity conditions they show different degrees of heat conductivity leading to a potential difference between them causing an output voltage from the bridge circuit, the intensity of which is increased as the absolute humidity of the air increases. Since the output is very minute, it is amplified by the operational amplifier.

 

 

 

 

Absolute humidity vs,

C

R1

Operational

output voltage characterist

amplifier

ge

 

 

 

Output

 

 

 

volta

 

 

+

voltage

 

 

 

 

 

-

 

Output

S

R2

 

S : Thermistor

R3

 

 

open vessel

 

 

 

C : Thermistor

 

 

 

 

closed vessel

 

 

 

 

 

Absolute humidity (g/m 2 )

(3)Detector Circuit of Absolute Humidity Sensor Circuit This detector circuit is used to detect the output voltage of the absolute humidity circuit to allow the LSI to control sensor cooking of the unit. When the unit is set in the sensor cooking mode, 16 seconds clearing cycle occurs

than the detector circuit starts to function and the LSI observes the initial voltage available at its AN6 terminal. With this voltage given, the switches SW1 to SW5 in the LSI are turned on in such a way as to change the resistance values in parallel with R50-1. Changing the resistance values results in that there is the same potential at both F-3 terminal of the absolute humidity sensor and AN7 terminal of the LSI. The voltage of AN6 terminal will indicate about -2.5V. This initial balancing is set up about 16 seconds after the unit is put in the Sensor Cooking mode. As the sensor cooking proceeds, the food is heated to generate moisture by which the resistance balance of the bridge circuit is deviated to increase the voltage available at AN6 terminal of the LSI. Then the LSI observes that voltage at AN6 terminal and compares it with its initial value, and when the comparison rate reaches the preset value (fixed for each menu to be cooked), the LSI causes the unit to stop sensor cooking; thereafter, the unit goes in the next operation automatically.

When the LSI starts to detect the initial voltage at AN6 terminal 16 seconds after the unit has been put in the Sensor Cooking mode, if it is not possible to balance, of the bridge circuit due to disconnection of the absolute humidity sensor, ERROR will appear on the display and the cooking is stopped.

1) Absolute humidity sensor circuit

 

IC2(IZA495DR)

 

 

SW1

 

 

4

64

 

 

P30

 

620k

 

 

 

5

63

SW2

 

 

P31

 

300k

 

 

 

6

62

SW3

 

 

P32

 

150k

 

 

 

7

61

SW4

 

75k

 

 

P33

C. Thermistor in

8

60

SW5

37.4k

 

 

P34

closed vesssl

 

 

 

S. Thermistor in

 

 

 

 

open vessel

 

3

5

 

F-1

11

 

47k

0.01µF

0.015µF

0.01µF

AN7

 

LSI

 

 

 

 

 

 

 

C

 

 

 

 

 

 

(IC1)

 

 

 

 

 

 

 

F-3

3.57k

 

+

 

10k

 

 

 

 

 

2

6

 

 

 

 

S

 

 

0.1 µF

 

 

47k

AN6

3.32k

-

 

 

 

F-2

1.8k

 

 

 

 

10

 

 

360k

 

 

 

 

 

 

 

 

 

 

R51

9

 

 

 

 

 

 

 

12

 

1

 

 

 

 

 

 

 

VA : -15V

 

VA : -15V

VC : -5V

 

27

Image 29
Contents Models DMOC205SS VMOC205SS Table of ContentsBefore Servicing DMOC205SS VMOC205SS Before Servicing When the testing is completedLeakage test with enclosure installed Microwave Measurement Procedure CanadaRequirements Leakage test without enclosureLeakage test Microwave Measurement Procedure USAMicrowave Ovens DMOC205SS VMOC205SS Foreword If provided, Vent Hood, Fan assembly, Cooling Fan MotorViking Range Corporation High MIX. Roast SpecificationDescription VMOC205SS Oven DiagramOperation Power Level P-0 to P-90 CookingDescription of Operating Sequence OFF ConditionAutomatic MIX Cooking Condition Convection Cooking ConditionSensor Cooking Condition Preheating ConditionCompu Defrost Cooking Fire Sensing Feature Microwave ModeCompu BROIL/ Compu ROAST/ Compu Bake Cooking SequenceFigure O-1. Oven Schematic-OFF Condition Schematic DiagramFigure O-3. Oven Schematic-Automatic Mix Cooking Condition Description and Function of Components Damper OPEN-CLOSE Mechanism Troubleshooting GuideMicrowave Cooking Damper OperationProblem Test ProcedureHigh Voltage Capacitor Test Power Transformer TestHigh Voltage Rectifier Test Primary Interlock Switch and Third Door Switch Test Test Procedures Letter Component TestMonitor Switch Secondary Interlock System TestChecking Temperature in the Convection Mode Damper Switch TestHeating Element Test Thermistor TestNoise Filter Test Touch Control Panel Assembly TestWeight 1ST Stage 2ND Stage 3RD Stage 4TH Stage Level Time Test Procedures Letter Component Test KEY Unit TestRelay Test Compu Defrost TestAH Sensor Test Steps Occurrence Cause or CorrectionChecking the initial sensor cooking condition Water load cooking testChecking Control Unit Testing Method for AH Sensor AND/OR Control UnitDescription of LSI Touch Control Panel AssemblyThermistor LSIIXA103DRDigit selection signal Temperature measurement input Oven ThermistorConvection motor driving signal Cooling fan motor driving signalTOR Key strobe signal Segment data signalsSegment data signal Structure of Absolute Humidity Sensor Absolute Humidity Sensor CircuitServicing Power Transformer Removal Component Replacement and Adjustment ProcedureOuter Case Removal Magnetron RemovalPositive Lock Connector NO-CASE Type Removal High Voltage Rectifier Assembly RemovalDamper Assembly Removal High Voltage Capacitor RemovalFAN Motor Removal Oven Lamp and Lamp Socket RemovalThermistor Removal Heating Element RemovalControl Unit and KEY Unit Power Supply Cord ReplacementControl Panel Assembly and Control Unit Removal Adjustment Door Replacement and AdjustmentAfter adjustment, check the following RemovalAfter adjustment, make sure of the following Door DisassemblyDoor Adjustment Preparation For Testing Microwave Measurement ProcedureLeakage test Leakage Test with Enclosure Installed RequirementFigure S-1. Pictorial Diagram SFigureControl Panel DIP Electrical Parts Parts ListCabinet Parts Control Panel PartsScrews Nuts and Washers Door PartsMiscellaneous LX-NZ0029YBE0 Oven and Cabinet Parts Control Panel Parts Door Parts Packing and Accessories DMOC205SS VMOC205SS Copyright 2004 by Viking

VMOC205SS, DMOC205SS specifications

The Viking DMOC205SS and VMOC205SS are two state-of-the-art microwave ovens that redefine cooking convenience and efficiency. Designed for modern kitchens, these appliances come equipped with a range of features and technologies that enhance their usability and performance.

One of the most notable aspects of the Viking DMOC205SS and VMOC205SS is their powerful cooking capabilities. Both models utilize an advanced cooking system that ensures even heat distribution, resulting in perfectly cooked meals every time. With a robust wattage of up to 1,200 watts, these microwaves can quickly and efficiently prepare a wide variety of dishes.

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Functionality is at the forefront of the Viking DMOC205SS and VMOC205SS. Both models are equipped with multiple cooking modes, including microwave, convection, and grilling options. This multi-functional capability allows users to seamlessly switch between cooking methods, ensuring optimal results for various recipes. The intuitive control panel features easy-to-read buttons and a digital display, making it user-friendly for all cooking levels.

In terms of technology, these Viking microwaves incorporate sensor cooking, which automatically detects the moisture and temperature of food, adjusting cooking times accordingly. This feature not only prevents overcooking but also ensures consistently delicious results. The models also come with pre-programmed cooking settings for popular dishes, making meal preparation simpler and quicker.

Energy efficiency is another critical aspect of the Viking DMOC205SS and VMOC205SS. Both models are designed to minimize energy consumption while maximizing performance, which is beneficial for both the environment and the homeowner’s energy bills.

Safety features are embedded within the design of these microwaves. They include a child lock function to prevent accidental use, as well as a timer that ensures food is cooked for the precise amount of time needed.

In summary, the Viking DMOC205SS and VMOC205SS are exceptional microwave ovens that combine advanced technology, practical features, and stylish design. Their powerful cooking capabilities, user-friendly controls, and energy-efficient operation make them a perfect addition to any modern kitchen. These appliances empower users to explore a wide range of cooking possibilities, bringing convenience and quality to meal preparation.