Sharp R-1490 User manual

R-1490
R-1491
R-1492
Intheinterestofuser-safetytheovenshouldberestoredtoitsoriginal
condition and only parts identical to those specified should be used.
WARNING TO SERVICE PERSONNEL: Microwave ovens con-
tain circuitry capable of producing very high voltage and
current, contact with following parts may result in a severe,
possibly fatal, electrical shock. (High Voltage Capacitor, High
Voltage Power Transformer, Magnetron, High Voltage Recti-
fier Assembly, 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................................................................................................................1
MICROWAVE MEASUREMENT PROCEDURE ...................................................................................................2
FOREWORD AND WARNING...............................................................................................................................3
PRODUCT SPECIFICATIONS ..............................................................................................................................4
GENERAL INFORMATION...................................................................................................................................4
OPERATION..........................................................................................................................................................6
TROUBLESHOOTING GUIDE ..............................................................................................................................8
TEST PROCEDURE ..............................................................................................................................................9
TOUCH CONTROL PANEL ASSEMBLY ............................................................................................................11
CONPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ................................................................13
PICTORIAL DIAGRAM ........................................................................................................................................15
CONTROL PANEL CIRCUIT ...............................................................................................................................16
PARTS LIST ........................................................................................................................................................17
PACKING AND ACCESSORIES .........................................................................................................................22
S4808R1490X//
R-1490
R-1491
R-1492
MODELS
SERVICE MANUAL
SHARP CORPORATION This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
This is a supplemental Service Manual for Models R-1490, R-1491 and R-1492. These models are quite similar to
base model R-1480,R-1481 and R-1482. Use this supplemental manual together with the Base Models Service
Manual (Refer No. is S3807R1480X//) for complete operation, service information, etc..
OVERTHE RANGE
MICROWAVE OVEN
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Power
Level Kitchen Timer
Clock Minute
Plus
Turntable
On/Off Stop
Clear Start
Touch On
Work
Light Night
Light Fan
Hi/Lo
Compu
Cook Compu
Defrost

Rice
Popucorn Reheat
Fresh/
seafood
Ground
meat
Frozen
vegetablest Frozen
entrees

Baked
potatoes
Frozen
vegetables
Custom 
Help
S e n s o r Co o k i n g

R-1490
R-1491
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PRECAUTIONSTO BE OBSERVED BEFORE AND
DURING SERVICINGTO AVOID POSSIBLE
EXPOSURETO 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.
(c) Before turning on microwave power for any service test or inspection within the microwave generating
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 releasing oven 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 SHARP ELECTRONICS
CORPORATION immediately @1-800-237-4277.
If the unit operates with the door open, service person should 1) tell the user not to operate the oven
and 2) contact SHARP ELECTRONICS CORPORATION and Food and Drug Administration's
Center for Devices and Radiological Health immediately.
ServicepersonnelshouldinformSHARPELECTRONICSCORPORATIONofanycertifiedunitfound
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.

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WARNINGTO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of pro-
ducing very high voltage and current, contact with
following parts
may result in a severe, possibly
fatal, electrical shock.
(Example)
HighVoltageCapacitor,HighVoltagePowerTrans-
former,Magnetron,HighVoltageRectifierAssem-
bly, High Voltage Harness etc..
Read the Service Manual carefully and follow all
instructions.
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
secondsaftertheovenhasbeenswitchedoff.Waitfor60
secondsandthenshort-circuittheconnectionofthehigh-
voltagecapacitor(thatistheconnectingleadofthehigh-
voltage rectifier) against the chassis with the use of an
insulated screwdriver.
Whenever troubleshooting is performed the power supply
mustbedisconnected.Itmayin,somecases,benecessary
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 these 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. Reconnectthe power supply cord after theouter 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. Reconnectthe power supply cord after theouter 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
remainscoldcarryoutBefore Servicingprocedureandre-
examine the connections to the component being tested.
When all service work is completed and the oven is fully
assembled,themicrowavepoweroutputshouldbechecked
and microwave leakage test should be carried out.
Don't Touch !
Danger High Voltage

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MICROWAVE MEASUREMENT PROCEDURE
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven
shouldnotexceed1mW/cm2atanypoint5cmormorefromtheexternalsurfaceoftheoven,measuredpriortoacquisition
byapurchaser,andthereafter(through the useful lifeoftheoven),5mW/cm2at any point5cmormorefromtheexternal
surface of the oven.
2) Safety interlock switches Primary interlock relay and door sensing switch shall prevent microwave radiation emission in
excess of the requirement as above mentioned, secondary interlock switch shall prevent microwave radiation emission
in excess of 5 mW/cm2at 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:
Surveyinstruments 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 (68˚F) 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.
Theplacing 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.
C. Leakage test:
Closed-door leakage test (microwave measurement)
1) Grasptheprobeofthesurveyinstrumentandholditperpendiculartothegapbetweenthedoorandthebodyoftheoven.
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) Checkforleakageatthedoorscreen,sheetmetalseamsandotheraccessiblepositionswherethecontinuityofthemetal
has been breached (eg., around the switches, indicator, and vents).
Whiletestingforleakagearoundthedoorpullthedoorawayfromthefrontoftheovenasfarasispermittedbytheclosed
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.
NOTE: After servicing, record data on service invoice and microwave leakage report.

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SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
SERVICE MANUAL
OVER THE RANGE MICROWAVE OVEN
R-1490/ R-1491/1492
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp. Service Personnel with Operation and Service Information
for the SHARP OVER THE RANGE MICROWAVE OVEN, R-1490/ R-1491/ R1492.
The models R-1490, R-1491 and R-1492 is quite similar to base models R-1480/81/82 (Refer No. is S3807R1480X//).
It is recommended that service personnel carefully study the entire text of this manual and base model service 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 not any 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.
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.
Allthepartsmarked“∆”onpartslistmaycauseunduemicrowaveexposure,bythemselves,orwhentheyaredamaged,
loosened or removed.

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ITEM DESCRIPTION
Power Requirements 120 Volts / 14.3 Amperes
60 Hertz
Single phase, 3 wire grounded
Power Output 950 watts (IEC-705 TEST PROCEDURE)
Operating frequency of 2450MHz
Convection Power Output 1700 watts
Case Dimensions Width 29-15/16"
Height 16-3/8"
Depth 15- 1/4" (Not including the door handle)
Cooking Cavity Dimensions Width 20-1/4"
Height 8-3/16"
1.4 Cubic Feet Depth 14-1/2"
Hood lamp 2 bulbs, 30W x 2, Incandescent light bulbs
Hood fan Approx. 300 C.F.M.
Control Complement Touch Control System
Clock ( 1:00 - 12:59 )
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
CUSTOM HELP pad, COMPU DEFROST pad, COMPU COOK pad,
SENSOR COOKING pad, Number selection pads, POWER LEVEL pad
KITCHEN TIMER / CLOCK pad, MINUTE PLUS pad
TURNTABLE ON / OFF pad, STOP / CLEAR pad, START / TOUCH ON pad
WORK LIGHT pad, NIGHT LIGHT pad, FAN HI / LO pad
Oven Cavity Light 30W x 1 Incandescent light bulb
Safety Standard UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
Weight Approx. 55 lbs.
PRODUCT 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 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.

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Electrical Requirements
The oven is equipped with a 3-prong grounding plug. DO NOT UNDER ANY CIRCUMSTANCES CUT OR REMOVE THE
GROUNDING PIN FROM THE PLUG.
Thepowersupply cordandplugmustbeconnectedto aseparate120VoltAC,60Hz, 15Amp.ormorebranchcircuit,using
a grounded receptacle. The receptacle should be located inside the cabinet directly above the Microwave Oven/Hood
system mounting location.
CONTROL PANEL
3-Pronged Plug
Grounded
Receptacle Box
Grounding Pin
3-Pronged Receptacle
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Power
Level Kitchen Timer Clock Minute Plus
Turntable
On/Off Stop Clear Start Touch On
Work
Light Night Light Fan Hi/Lo
Compu
Cook Compu Defrost

Rice
Popcorn Reheat
Fish/
seafood
Ground
meat
Fresh
vegetables Frozen entrees

Baked
potato
Frozen
vegetables
Custom 
Help
S e n s o r C o o k i n g

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R-1491
R-1492
OPERATION
DESCRIPTION OF OPERATING SEQUENCE
SENSOR COOKING CONDITION
UsingtheINSTANTSENSORfunction,thefoodsarecooked
or defrosted without figuring time, power level or quantity.
When the oven senses enough steam from the food, it
relaystheinformationtoitsmicroprocessorwhichwillcalcu-
latetheremainingcookingtimeandpowerlevelneededfor
best results.
When the food is cooked, water vapor is developed. The
sensor “senses” the vapor and its resistance increases
gradually. When the resistance reaches the value set ac-
cording to the menu, supplementary cooking is started.
Thetimeofsupplementarycookingisdeterminedbyexperi-
ment with each food category and inputted into the LSI.
An example of how sensor works (Baked potato):
1. Potatoes at room temperature. Vapor is emitted very
slowly.
MICROWAVE
2. Heatpotatoes.Moistureandhumidityisemittedrapidly.
You can smell the aroma as it cooks.
3. Sensor detects moisture and humidity and calculates
cooking time and variable power.
Cooking Sequence.
1. Touch one of the INSTANT SENSOR pads.
NOTE: The oven should not be operated on INSTANT
SENSOR immediately after plugging in the unit.
Wait two minutes before cooking on INSTANT
SENSOR.
2. Thecoilofshut-offrelays(RY1andRY3)areenergized,
theovenlamp,turntablemotorandcoolingfanmotorare
turned on, but the power transformer is not turned on.
3. Afterabout32seconds,thecookrelay(RY2)isenergized.
The power transformer is turned on, microwave energy
is produced and first stage is started.
The 32 seconds is the cooling time required to remove
any vapor from the oven cavity and sensor.
NOTE: Duringthisfirststage,donotopenthedoorortouch
STOP/CLEAR pad.
4. When the sensor detects the vapor emitted from the
food,thedisplay switchesovertothe remainingcooking
time and the timer counts down to zero.
At this time, the door may be opened to stir food, turn it
or season, etc.
5. Whenthetimerreacheszero, an audible signal sounds.
The shut-off relay and cook relay are de-energized and
the power transformer, oven lamp, etc. are turned off.
6. OpeningthedoorortouchingtheSTOP/CLEARpad,the
timeofdaywill reappearonthedisplayand theovenwill
revert to an OFF condition.
MICROWAVE
AH SENSOR

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SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED
2. COOKING TIME PROGRAMMED
3. VARIABLE COOKING CONTROL "HIGH"
4. "START" PAD TOUCHED
Figure O-2. Oven Schematic-Cooking Condition
Figure O-1. Oven Schematic-Off Condition
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED
2. CLOCK APPEARS ON DISPLAY
CAVITY 
THERMAL CUT-OUT MAGNETRON  TEMPERATURE FUSE
FUSE 
20A
TURNTABLE MOTOR FAN MOTOR
STIRRER MOTOR
MAGNETRON
OVEN LAMP
MONITOR SWITCH
BLKWHT
AH SENSOR
POWER
TRANSFORMER
HIGH VOLTAGE
CAPACITOR
0.94µF
HIGH VOLTAGE
RECTIFIER
COM. N.O.
COM.
CONTROL UNIT
GND
GRN
HOOD
MOTOR
B7
B5
B3
B1
High
Low
A1 A3 B9 A7 A5 N.O.
F1
F2
F3
E1
E2
DOOR
SENSING
SWITCH
SECONDARY
INTERLOCK
SWITCH
120 V AC.
60 Hz
HOOD
LAMP
HL HL
RY3 RY1 RY2
PRIMARY INTERLOCK  RELAY
SSR
FM
STM
OL
TTM
HOOD FAN
THERMAL
CUT OUT
HOOD
CAPACITOR
RY4
RY5
N.C.
MAGNETRON 
TEMPERATURE FUSE
FUSE 
20A
TURNTABLE MOTOR FAN MOTOR
STIRRER MOTOR
MAGNETRON
OVEN LAMP
MONITOR SWITCH
BLKWHT
AH SENSOR
POWER
TRANSFORMER
HIGH VOLTAGE
CAPACITOR
0.94µF
HIGH VOLTAGE
RECTIFIER
COM. N.O.
COM.
CONTROL UNIT
GND
GRN
HOOD
MOTOR
B7
B5
B3
B1
High
Low
A1 A3 B9 A7 A5 N.O.
F1
F2
F3
E1
E2
DOOR
SENSING
SWITCH
SECONDARY
INTERLOCK
SWITCH
120 V AC.
60 Hz
HOOD
LAMP
HL HL
RY3 RY1 RY2
PRIMARY INTERLOCK  RELAY
FM
STM
OL
TTM
HOOD FAN
THERMAL
CUT OUT
HOOD
CAPACITOR
RY4
RY5
N.C.
CAVITY 
THERMAL CUT-OUT
SSR

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TROUBLESHOOTING GUIDE
Nevertouchanypartinthecircuitwithyourhandoranuninsulatedtoolwhilethepowersupplyisconnected.
Whentroubleshootingthe microwaveoven,itishelpfultofollowtheSequence ofOperationinperforming thechecks.Many
ofthepossiblecausesoftroublewillrequirethataspecifictestbeperformed.Thesetestsaregivenaprocedureletterwhich
will be found in the "Test Procedure "section.
IMPORTANT: If the oven becomes inoperative because of a blown monitor fuse, check the monitor switch, relay (RY1)
primary interlock relay (RY2), door sensing switch and secondary interlock switch before replacing the
monitor fuse. If monitor fuse is replaced, the monitor switch must also be replaced. Use part FFS-BA016/
KiT as an assembly.
IMPORTANT: Whenever 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. Ensurethatthe leadsremainisolatedfromothercomponentsandovenchassis byusinginsulationtape.
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.
LQCK
CONTROL UNIT AH SENSOR SHORTED OR OPENED WIRING
The oven stops and "ERROR" is displayed or does not end during Sensor Cooking
condition. (Oven does not shut off after a cup of water is boiling by Sensor Cooking.)
Oven stops at 32 seconds after starting.
TEST PROCEDURE
PROBLEM
CONDITION
SENSOR
COOKING
CONDITION
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
NOTE: For additional troubleshooting procedures, please refer back to the R-1480 base model Service Manual.