background image

25

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.

(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  150

o

C  (302

o

F),  the  resultant  heat  is 

dissipated in the air and if the two thermistors are placed 
in  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 inceases.  
Since the output is very minute, it is amplified by the 
operational amplifier.

(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 then the detector circuit starts to function and 
the LSI observes the initial voltage available at its AN1 
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 R107 ~ R111 of IC2 
.  Changing the resistance value results in that there is 
the same potential at both F-3 terminal of the absolute 
humidity sensor and AN0 terminal of the LSI.  The voltage 
of    AN1  terminal  will  indicat  about  16  seconds  about  
-2.50          V.  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 AN1 terminal of the LSI.

  Then the LSI observes that the voltage at AN1 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 AN1 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              

ventilation opening for sensing

Sensing part
(Open vessel)

Sensing part
(Closed vessel)

Thermistors

C

S

R3

R1

R2

+

Operational

amplifier

Output

voltage

S : Thermistor

     open vessel

C : Thermistor

      closed vessel

2

Absolute humidity (g/m  )

O

ut

pu

t v

ol

ta

ge

Absolute humidity vs,

output voltage characteristic

SW1

SW2

SW3

SW4

SW5

P20

P21

P22

P23

P24

 LSI

(IC1)

AIN4

AIN5

620k

300k

150k

75k

37.4k

47k

47k

10k

1 2 3 4

8 7 6 5

0.01uF

0.015uF

0.01uF

VA : -15V

VA : -15V

R90

C

90

C

91

C

93

C92

S

F-2

1.8k

IC2

F-1

F-3

C

3.57k

3.32k

VC : -5V

0.1 uF

C. Thermistor in 

    closed vessel

S. Thermistor in

    open vessel

R98

R99

R96

R91

360k

R93

R92

R94

R95

D91

D90

R100

R101

R102

R97

Содержание VMOS201AR

Страница 1: ...RE TO EXCESSIVE MICROWAVE ENERGY 2 BEFORE SERVICING 2 WARNING TO SERVICE PERSONNEL 4 MICROWAVE MEASUREMENT PROCEDURE 5 FOREWORD AND WARNING 7 PRODUCT SPECIFICATIONS 8 GENERAL INFORMATION 8 OPERATION 10 TROUBLESHOOTING GUIDE 14 TEST PROCEDURE 15 COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE 26 PICTORIAL DIAGRAM 32 PARTS LIST 33 PACKING AND ACCESSORIES 37 S11326MOS201 MICROWAVE OVEN MODELS SERVICE ...

Страница 2: ...k as per the Microwave Measure ment 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 Cente...

Страница 3: ...3 Notes ...

Страница 4: ...citor 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...

Страница 5: ... 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 fast...

Страница 6: ...ity 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...

Страница 7: ...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 person nel Do not contact the following parts while the appliance is energized HighVoltage Capacitor PowerTransformer Magnetron HighVolt age Rectifier Assembly High Voltage Harness If provided Vent Hood Fan assembly C...

Страница 8: ...les CFR Title 21 Chapter 1 Subchapter J and Canadian Standards Association Health CANADA SPECIFICATION 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 accordance with the National Electrical Code and local codes and ordinances In the event of an electrical short c...

Страница 9: ...r accidentally CAUTION DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE ROUND GROUNDING PRONG FROM OVEN DIAGRAM 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 Removable turntable The turntable will rotate clockwise or counterclockwise 5 Oven lamp It will light when oven is operating or door ...

Страница 10: ...ndary interlock relay 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 electrically monitors the operation of the primary switch and primary and is mecha...

Страница 11: ...of the SENSOR pads NOTE The oven should not be operated on sensor immediately after plugging in the unit Wait two minutes before cooking on SENSOR 2 Thecoilofshut offrelay RY 1 isenergized theturntable 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 microwaveenergyisproducedandfirststageisst...

Страница 12: ... H N NOIS E FILTE R UNIT N O COM DOOR S E NS ING S WITCH NOIS E S UP P R E S S ION C OIL LINE C R OS S C AP AC IT OR 0 22uF AC 250V 0 0033uF AC 125V 0 0033uF AC 125V LINE B Y P AS S C AP AC IT OR LINE B Y P AS S C AP AC IT OR N O COM COM OL 120V AC 60 Hz MONITOR S WITCH H V R E CTIFIE R MAGNE TR ON S E CONDAR Y S WITCH MONIT OR F US E C AV IT Y T E MP F US E MAG NE T R ON T E MP F US E A1 A2 COM N...

Страница 13: ...ION BEFORE REPLACING A BLOWN monitor FUSE TESTMONITORSWITCHANDPRIMA RY SWITCH FOR PROPER OPERATION RE FER TO CHAPTER TEST PROCEDURE NOTE monitor FUSE AND MONITOR SWITCH ARE REPLACED AS AN ASSEMBLY TURNTABLE MOTOR The turntable motor rotates the turntable located on the bottom of the oven cavity so that the foods on the turntable cook evenly during cooking The turntable may turn in either direction...

Страница 14: ...er troubleshooting is performed with the power supply cord disconnected It may in some cases be necessary to connect the power supply cord 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 t...

Страница 15: ...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 Oven lamp does not go out when door is closed Oven lamp lights but fan motor and turntable motor do not operate Oven does not go into cook cycle when START pad is touched Oven seems to be operating but little or no heat is produced in oven load Food incomplete...

Страница 16: ...ERVED Power output of the magnetron can be measured by performing a water temperature rise test This test should only be used if above tests do not indicate a faulty magnetron and there is no defect in the following components or wiring silicon rectifier high voltage capacitor and power transformer This test will require a 16 ounce 453cc measuring cup and an accurate mercury thermometer or thermoc...

Страница 17: ... oven cavity especially the cooling fan and air guide 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 MAGNETRON TEMPERATURE FUSE TEST 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 3 Discharge hig...

Страница 18: ...secondary interlock switch 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 SECONDARY INTERLOCK SYSTEM TEST DOOR SENSING SWITCH 1 Disconnect the power supply cord and then remove outer case 2 Open the door and block it open 3 Discharge high volta...

Страница 19: ...el assembly is divided into two units Con trol Unit and Key Unit and also the Control Unit is divided into two units LSI Unit and Power Unit and troubleshooting by unit replacement is described according to the symptoms indicated Before testing 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 t...

Страница 20: ...duces no signal 2 3 Other possible problems caused by defective control unit a Buzzer does not sound or continues to sound b Clock does not operate properly c Cooking is not possible When 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 all leads removed from components during testing...

Страница 21: ...y RY1 on the control unit with an A C voltmeter The meter should indicate 120 volts if not check oven circuit RY1 and RY2 Relay Test These relays are operated by D C voltage Check voltage at the relay coil with a D C voltmeter during the microwave cooking operation DC voltage indicated Defective relay DC voltage not indicated Check diode which is connected to the relay coil If diode is good contro...

Страница 22: ...00 milliliters measuring cup 3 Place the container on the center of tray in the oven cavity 4 Close the door 5 Touch the Timer Clock pad once the Power Level pad twice the Start pad once and the number one once Now the oven is in the sensor cooking condition and TEST SENSOR and COOK will appear in the display 6 The oven will operate for the first 16 seconds without generating microwave energy NOTE...

Страница 23: ...pproximately 25 seconds push plunger of select switch for more than 3 seconds This condition is same as judgement by AH sensor 9 4 After approximately 3 seconds the display shows xx xx which is remaining cooking time and the display count down If the above is not the case the control unit is probably defective If the above is proper the AH sensor is probably defective 10 Disconnect the power suppl...

Страница 24: ... INDICATION OF OHM METER Between N and H Open Circuit Between terminal N and GRY Short Circuit Between terminal H and RED Short Circuit If incorrect readings are obtained replace the noise filter 6 Reconnect all leads removed from components during testing 7 Re install the outer case cabinet 8 Reconnect the power supply cord after the outer case is installed 9 Run the oven and check all functions ...

Страница 25: ... resistance values in parallel with R107 R111 of IC2 Changing the resistance value results in that there is the same potential at both F 3 terminal of the absolute humiditysensorandAN0terminaloftheLSI Thevoltage of AN1 terminal will indicat about 16 seconds about 2 50 V This initial balancing is set up about 16 secondsaftertheunitisputintheSensorCookingmode As the sensor cooking proceeds the food ...

Страница 26: ... 1 Disconnect the power supply cord 2 Make sure that a definite click can be heard when the microwave oven door is unlatched Hold the door in a closed position with one hand then push the door open button with the other this causes the latch leads to rise it is then possible to hear a click as the door switches operate 3 Visuallycheckthedoorandcavityfaceplatefordamage dents cracks signs of arcing ...

Страница 27: ...of the power transformer from the high voltage capacitor 7 Remove one 1 screw holding capacitor holder with the high voltage rectifier to the base plate 8 Disconnect rectifier terminal from capacitor High voltage rectifier assembly is now free 9 Remove capacitor holder Capacitor is now free CAUTION WHEN REPLACING HIGH VOLTAGE REC TIFIER AND HIGH VOLTAGE CAPACITOR GROUND SIDE TERMINAL OF THE HIGH V...

Страница 28: ... of control panel frame 3 Stick the key unit firmly to the control panel frame by rubbing with soft cloth not to scratch LSI UNIT NOTE Handle the LSI unit carefully so that there is no excessive force applied to the ribbon connection LSI unit 2 Remove turntable and turntable support from oven cavity 3 Laytheovenonit sbackside Removetheturntablemotor cover by snipping off the material in four corne...

Страница 29: ...oth after installation Make sure that the axis of the shaft is not slanted 5 Install the fan motor to the the oven cavity back plate with the two 2 screws 6 Connect the wire leads to the fan motor referring to the pictorial diagram Side View Rear View 1 Disconnect the power supply cord and remove outer case 2 Open the door and block it open 3 Discharge high voltage capacitor 4 Disconnect wire lead...

Страница 30: ... pushing and pulling upper portion of door toward the oven face Then check lower portion of the latch Figure C 3 Latch Switch Adjustments hook pushing and pulling upper portion of door toward the oven face Both results play in the door should be less than 0 5mm 2 The door sensing switch primary switch and secondary switch interrupt the circuit before the door can be opened 3 Monitor switch contact...

Страница 31: ...d toward cavity face plate 4 Check for microwave leakage around door with an approved microwave survey meter Refer to Microwave Measurement Procedure Note The door on a microwave oven is designed to act as an electronic seal preventing the leakage of microwave energy from oven cavity during cook cycle This function does not require that door be air tight moisture condensation tight or light tight ...

Страница 32: ...ust be connected to the terminal with N mark on the power supply cord BLK WHT H N NOTE The grounding conductor of the power supply cord has been grounded by power supply cord fixing screw The screw must always be kept tight COM N O DOOR SENSING SWITCH PNK GRN GRN to Oven cavity GRN PNK GRN 2 1 CN B ORG BLK SECONDARY SWITCH COM NO YLW BLK BRN WHT WHT RED RED GRY WHT BLK To CN A CN B RY1 IC1 PRIMARY...

Страница 33: ...ARTS 3 1 CPWBFB140MRU0 Control unit 1 3 2 FPNLCB408MRK0A Control panel frame with key unit VMOS201SS 1 3 2 FPNLCB543MRK0B Control panel frame with key unit VMOS201WH 1 3 2 FPNLCB616MRK0A Control panel frame with key unit VMOS201PL 1 3 2 FPNLCB545MRK0B Control panel frame with key unit VMOS201BT 1 3 2 FPNLCB546MRK0B Control panel frame with key unit VMOS201SG 1 3 2 FPNLCB547MRK0B Control panel fram...

Страница 34: ...RK0A Door assembly VMOS201OG 1 5 1 CDORFB509MRK0A Door assembly VMOS201GM 1 5 1 CDORFB510MRK0A Door assembly VMOS201SA 1 5 2 LSTPPB021MRF0A Latch head 1 AE 5 3 MSPRTA046WRE0 Latch spring 1 AB 5 2 FDORFB075MRT0 Door panel 1 AX 5 3 GCOVHB028MRF0 Choke cover 1 MISCELLANEOUS 6 1 TCAUHB008MRR0 User caution label 1 AF 6 2 FW VZC288WREZ Main wire harness 1 AU 6 3 FROLPA117WRKZ Turntable support 1 AN 6 4 ...

Страница 35: ...1 1 11 4 10 7 2 7 2 1 12 1 9 7 3 7 6 7 6 1 8 7 4 7 4 4 2 7 4 1 10 7 9 4 4 7 1 4 1 1 1 1 2 2 2 2 2 2 2 2 2 7 5 7 5 7 5 6 5 4 5 1 13 7 5 7 7 7 5 7 5 7 5 7 7 4 3 1 7 1 7 1 6 1 7 7 1 6 12 6 6 6 13 7 10 1 6 1 4 1 3 7 8 4 12 4 13 4 14 4 15 4 16 6 4 5 1 2 3 6 4 5 1 2 3 A B C D E F G H A B C D E F G H ...

Страница 36: ... 4 5 1 2 3 6 4 5 1 2 3 A B C D E F G H A B C D E F G H DOOR PARTS MISCELLANEOUS CONTROL PANEL PARTS 5 1 5 3 5 2 5 4 Actual wire harness may be different from illustration 6 8 6 2 3 4 3 2 3 3 3 5 3 5 3 1 6 1 ...

Страница 37: ...CESSORIES Non replaceable items DOOR PROTECTION SHEET PLASTIC BAG PACKING CASE TOP PAD ASSEMBLY INTO THE OVEN CAVITY 6 4 TURNTABLE TRAY 6 3 TURNTABLE SUPPORT 6 7 VIKING CD BOTTOM PAD ASSEMBLY TRAY HOLDER 6 9 RECIPE CARD ...

Страница 38: ...38 NOTES ...

Страница 39: ...39 NOTES ...

Страница 40: ...stem or transmitted in any form or by any means electronic mechanical photocopying recording or otherwise without prior written permission of the publisher COPYRIGHT 2011 BY VIKING ALL RIGHTS RESERVED VIKING RANGE CORPORATION 111 Front St Greenwood MS 38930 Tel 888 845 4641 ...

Отзывы: