Sharp R-1870 User Manual 2
SUPPLEMENTAL SERVICE MANUAL
S91M173R1870E
OVER THE RANGE
MICROWAVE OVEN
MODELS R-1870/R-1871
Model R-1870
R-1870
R-1871
This is a supplemental Service Manual for Models R-1870/R1871.
This model is quite similar to Base Model R-1850 (S/M# S6804R1850X//).
Use this supplemental manual together with the Base Model Service Manuals for complete operation and service information
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 following parts may result in a severe, possibly fatal, electrical shock. (High Voltage Capacitor, High
Voltage Power Transformer, Magnetron, High Voltage Rectifier 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
COMPONENT TEST .............................................................................................................................................9
PICTORIAL DIAGRAM ........................................................................................................................................10
LSI UNIT CIRCUIT...............................................................................................................................................11
PARTS LIST........................................................................................................................................................12
PACKING AND ACCESSORIES .........................................................................................................................18
SHARP ELECTRONICS CORPORATION
Service Headquarters: Sharp Plaza, Mahwah, New Jersey, 07430-2135
This document has been published to be used for after
sales service only.
The contents are subject to change without notice.
R-1870
R-1871
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.
(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 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 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.
Service personnel should inform SHARP ELECTRONICS CORPORATION 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.
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 Trans-
former, 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
R-1870
R-1871
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 highvoltage capacitor (that is the connecting lead of the highvoltage 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 reexamine 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.
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R-1870
R-1871
MICROWAVE MEASUREMENT PROCEDURE
A. Requirements:
1) Microwave leakage limit (Power density limit): The power density of microwave radiation emitted by a microwave oven
should not exceed 1mW/cm2 at any point 5cm or more from the external surface of the oven, measured prior to acquisition
by a purchaser, and thereafter (through the useful life of the oven), 5 mW/cm2 at any point 5cm or more from the external
surface of the oven.
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/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±5C (68F) 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.
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 secondary interlock switch does turn the oven OFF before any door movement.
NOTE: After servicing, record data on service invoice and microwave leakage report.
2
SERVICE MANUAL
PRODUCT DESCRIPTION
R-1870
R-1871
MICROWAVE OVEN
R-1870/R1871
FOREWORD
This Manual has been prepared to provide Sharp Electronics Corp.
Service Personnel with Operation and Service Information for the SHARP
MICROWAVE OVEN, R-1870 and R-1871.
The models R-1870 and R-1871 are quite similar to base model R-1850
(Ref.#
S6804R1850X//)
It is recommended that service personnel carefully study the entire text
of this manual and the base model's 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.
GENERAL INFORMATION
OPERATION
TROUBLESHOOTING GUIDE AND
TEST PROCEDURE
TOUCH CONTROL PANEL
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
WIRING DIAGRAM
PARTS LIST
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.
SHARP ELECTRONICS CORPORATION
SHARP PLAZA, MAHWAH,
NEW JERSEY 07430-2135
3
R-1870
R-1871
SPECIFICATION
ITEM DESCRIPTION
Power Requirements 120 Volts / 13.2 Amperes (Microwave), 13.2 Amperes (Convection)
60 Hertz
Single phase, 3 wire grounded
Power Output 850 watts (IEC-705 TEST PROCEDURE)
Operating frequency of 2450MHz
Convection Power Output 1400 watts
Case Dimensions Width 29-15/16"
Height 16-11/32"
Depth 15- 9/32"
Cooking Cavity Dimensions Width 17-1/8"
Height 8-1/16"
1.1 Cubic Feet Depth 13-13/16"
Hood lamp 2 bulbs, 30W x 2, Incandescent light bulbs
Hood fan Horizontal discharge 230 C.F.M. , Vertical discharge 240 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 Powe
P-0......................................................No power throughout the cooking time
CUSTOM HELP pad, SENSOR COOK pad, COMPU BROIL pad, COMPU ROAST pad
COMPU BAKE pad, SENSOR REHEAT pad, MINUTE PLUS pad, POPCORN pad
COMPU DEFROST pad, CONVECTION pad, REHEAT pad, LOW MIX/BAKE pad
HIGH MIX/ROAST pad, BROIL pad, SLOW COOK pad, KITCHEN TIMER pad
Number and temperature selection pads, CLOCK pad, KEEP WARM pad
TURNTABLE ON / OFF pad, POWER LEVEL pad, STOP/CLEAR pad,
START / TOUCH ON pad
Oven Cavity Light Yes 30W x 1 Incandescent light bulb
Safety Standard UL Listed FCC Authorized
DHHS Rules, CFR, Title 21, Chapter 1, Subchapter J
Weight Approx. 71 lbs.
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.
4
R-1870
CONTROL PANEL
g
R-1871
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.
The power supply cord and plug must be connected to a separate 120 Volt AC, 60 Hz, 15 Amp. or more branch circuit, using
a grounded receptacle. The receptacle should be located inside the cabinet directly above the Microwave Oven/Hood
system mounting location.
Grounded
Receptacle Box
12
3-Pronged Plug
Grounding Pin
3-Pronged Receptacle
OVEN DIAGRAM
1
11
10
3
13
5
4
9
8
6
2
6
7
17
14
16
15
1. Oven door with see-through window.
2. Door hinges.
3. Stirrer cover.
4. Turntable motor shaft.
5. Oven lamp.
It will light when oven is operating or door is open.
6. Door latches.
The oven will not operate unless the door is securely closed.
7. One touch door open button.
Push to open door.
8. FAN-HI/LO button.
Push for High/Low/Off.
9. Light button.
Push for On/Off
10.Auto-Touch control panel.
11.Time display: Digital display, 99 minutes 99 seconds.
12.Ventilation openings.
13.Light Cover.
14.Grease filters.
15.Removable turntable.
The turntable will rotate clockwise or counterclockwise.
Only remove for cleaning.
16.Removable turntable support.
17.Plu
NOTE:
Some one-touch cooking features
as "MINUTE PLUS" are disabled after one minute when the oven is not
used. These features are automatically enabled when the door is
opened and closed or the STOP/
CLEAR pad is pressed.
MIX CONV
DEFROST
SENSOR
ON OFF COOK LBS OZ KG HELP
TURNTABLE
5
R-1870
R-1871
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, 120 volts A.C. is supplied to the
control unit. (Figure O-1).
1. The display will show SHARP, SIMPLY, THE, BEST,
PRESS, CLEAR, and PRESS, CLOCK.
To set any program or set the clock, you must first touch
the STOP/CLEAR pad. The display will clear, and " : "
will appear.
COOKING CONDITION
Program desired cooking time touching the NUMBER
pads. 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
RY 2 Power transformer/ Stirrer motor
RY4 Turntable motor
RY 5 Fan motor
2. 120 volts A.C. is supplied to the primary winding of the
power transformer and is converted to about 3.3 volts A.C.
output on the filament winding, and approximately 2000
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, monitor
switch, door sensing switch, primary switch and secondary
switch and secondary interlock relay are activated with
the following results. The circuits to the stirrer motor, the
cooling fan motor, the turntable motor, and the high
voltage components are de-energized, 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 primary and secondary switch and secondary
interlock relay 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
secondary interlock relay, door sensing switch, primary
and secondary switch open their contacts, and then
the monitor switch contacts close.
(2 ) When the door is closed from the open position, the
monitor switch contacts first open, and then the
contacts of the primary and secondary switch close.
If the primary switch, secondary switch and secondary
interlock relay 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, secondary
switch switch, primary switch and secondary interlock
relay, causing the monitor fuse to blow.
POWER LEVEL P-0 TO P-90 COOKING
When Variable Cooking Power is programmed, the 120
volts A.C. is supplied to the power transformer
intermittently through the contacts of relay (RY2) which is
operated by the control unit within an interval second 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.
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