R-330H
SHARP CORPORATION
SERVICE MANUAL
S8305R330HPJ/
MICROWAVE OVEN
MODEL
R-330H
In interests of user-safety the oven should be restored to its
original condition and only parts identical to those specified
should be used.
TABLE OF CONTENTS
Page
CAUTION, MICROWAVE RADIATION............................................................................................................. 1
WARNING..........................................................................................................................................................1
PRODUCT SPECIFICATIONS ......................................................................................................................... 2
GENERAL INFORMATION................................................................................................................................2
APPEARANCE VIEW ....................................................................................................................................... 3
OPERATION SEQUENCE................................................................................................................................ 4
FUNCTION OF IMPORTANT COMPONENTS ................................................................................................ 5
SERVICING AND TROUBLESHOOTING GUIDE ............................................................................................ 6
TEST PROCEDURE......................................................................................................................................... 8
TOUCH CONTROL PANEL.............................................................................................................................14
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE........................................................... 19
MICROWAVE MEASUREMENT .................................................................................................................... 25
WIRING DIAGRAM......................................................................................................................................... 26
PICTORIAL DIAGRAM ................................................................................................................................... 27
CONTROL UNIT CIRCUIT ..............................................................................................................................28
PRINTED WIRING BOARD .............................................................................................................................29
PARTS LIST ................................................................................................................................................... 30
R-330H
R-330H
1
SERVICE MANUAL
MICROWAVE OVEN
R-330H
GENERAL IMPORTANT INFORMATION
This Manual has been prepared to provide Sharp Corp. Service
engineers with Operation and Service Information.
It is recommended that service engineers carefully study the
entire text of this manual, so they will be qualified to render
satisfactory customer service.
CAUTION
MICROWAVE RADIATION
DO NOT BECOME EXPOSED TO RADIATION FROM
THE MICROWAVE GENERATOR OR OTHER PARTS
CONDUCTING MICROWAVE ENERGY.
Service engineers should not be exposed to the microwave
energy which may radiate from the magnetron or other
microwave generating devices if it is improperly used or
connected. All input and output microwave connections,
waveguides, flanges and gaskets must be secured. Never
operate the device without a microwave energy absorbing
load attached. Never look into an open waveguide or
antenna while the device is energized.
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 engineers.
All the parts marked "*" on parts list are used at voltages more
than 250V.
Removal of the outer wrap gives access to potentials above
250V.
All the parts marked "∆" on parts list may cause undue microwave exposure, by themselves, or when they are damaged,
loosened or removed.
SHARP CORPORATION
OSAKA, JAPAN
PRODUCT SPECIFICATIONS
APPEARANCE VIEW
OPERATING SEQUENCE
FUNCTION OF IMPORTANT
COMPONENTS
SERVICING AND
TROUBLESHOOTING CHART
TEST PROCEDURE
TOUCH CONTROL PANEL
ASSEMBLY
COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE
MICROWAVE MEASUREMENT
WIRING DIAGRAM
PARTS LIST
R-330H
2
ITEM DESCRIPTION
Power Requirements 230 - 240 Volts
50 Hertz
Single phase, 3 wire earthed
Power Consumption 1.6kW
Power Output 1100 watts nominal of RF microwave energy (IEC Test Procedure)
Operating frequency 2450 MHz
Case Dimensions Width 520 mm
Height 310 mm including foot
Depth 459 mm
Turntable diameter 320 mm
Control Complement Touch Control System
Clock ( 1:00 - 12:59)
Timer (0 - 99 minutes 99 seconds)
Microwave Power for Variable Cooking
Repetition Rate;
100P................................................Full power throughout the cooking time
70P.....................................................................approx. 70% of Full Power
50P......................................................................approx. 50% of Full Power
30P......................................................................approx. 30% of Full Power
10P......................................................................approx. 10% of Full Power
INSTANT ACTION pads
EASY DEFROST pad
EXPRESS DEFROST pad
NUMBER pads
POWER LEVEL pad
TIMER/CLOCK pad
STOP/CLEAR pad
INSTANT COOK/START pad
Set Weight Approx. 16 kg
PRODUCT SPECIFICATIONS
GENERAL INFORMATION
WARNING
THIS APPLIANCE MUST BE EARTHED
IMPORTANT
THE WIRES IN THIS MAINS LEAD ARE COLOURED IN ACCORDANCE WITH THE FOLLOWING CODE:
GREEN-AND-YELLOW : EARTH
BLUE : NEUTRAL
BROWN : LIVE
R-330H
3
APPEARANCE VIEW
1. Door open button
2. Door safety latches
3. Removable turntable support
4. Removable turntable tray
5. Oven lamp
6. See through door
7. Ventilation openings
8. Touch control panel
9. Liquid crystal display
10.Coupling
11.Waveguide cover
12.Power supply cord
13.Door hinges
14.Door seals and sealing surfaces
TOUCH CONTROL PANEL
NOTE:
Some one-touch cooking features such as "INSTANT COOK" are disabled after three minutes when
the oven is not in use. These features are automatically enabled when the door is opened and closed
or the STOP/ CLEAR pad is pressed.
8
9
12
4
7
1
3
14
26
13
10
11 25
EXPRESS DEFROST PAD
Press to select the Express
Defrost menu.
POWER LEVEL PAD
Press to select microwave
power setting.
If not pressed, HIGH is automatically selected. Press to
alter the cookingresult for automaticoperations.
STOP/CLEAR PAD
Press to clear during programming.
Press once to stopoperation
of oven duringcooking; press
twice tocancel cooking programme.
INSTANT ACTION PADS
Press to cook or reheat 8
popular menus.
EASY DEFROST PAD
Press to selectthe Easy Defrost
menu.
NUMBER PADS
Press to enter cooking time,
clock time, weight of food.
TIMER/CLOCK PAD
Press to set clock, timer, childlock
or demonstration mode.
INSTANT COOK/START PAD
Press to start oven after setting
programmes.
Press once to cook for 1 minute
at HIGH or increase by 1 minute
multiples each time this pad is
pressed during cooking.
Indicators
R-330H
4
OPERATION SEQUENCE
OFF CONDITION
Closing the door activates all door interlock switches
(1st. latch switch and 2nd. interlock relay control switch).
IMPORTANT
When the oven door is closed, the monitor switch contacts
(COM-NC) must be open.
When the microwave oven is plugged in a wall outlet, rated
voltage is supplied to the noise filter and the control unit.
Figure O-1 on page 25
1. The display shows flashing "88:88".
2. To set any programmes or set the clock, you must
first touch the STOP/CLEAR pad.
3. : appears in the display.
NOTE: When the oven door is opened, the oven lamp
comes on at this time.
MICROWAVE COOKING CONDITION
HIGH COOKING
Enter a desired cooking time with the touching NUMBER
pad and start the oven with touching START pad.
Function sequence
Figure O-2 on page 25
CONNECTED COMPONENTS RELAY
Oven lamp, Fan motor, Turntable motor RY1
Power transformer RY2
1. Rated voltage is supplied to the primary winding of the
power transformer. The voltage is converted to about
3.3 volts A.C. output on the filament winding and high
voltage of approximately 2000 volts A.C. on the
secondary winding.
2. The filament winding voltage (3.3 volts) heats the
magnetron filament and the high voltage (2000 volts) is
sent to the voltage doubling circuit, where it is doubled
to negative voltage of approximately 4000 volts D.C..
3. The 2450 MHz microwave energy produced in the
magnetron generates a wave length of 12.24 cm. This
energy is channelled through the waveguide (transport
channel) into the oven cavity, where the food is placed
to be cooked.
4. When the cooking time is up, a signal tone is heard and
the relays RY1+RY2 go back to their home position.
The circuits to the oven lamp, power transformer, fan
motor and turntable motor are cut off.
5. When the door is opened during a cook cycle, the
switches come to the following condition
CONDITION
DURING DOOR OPEN
SWITCH CONTACT COOKING
(NO COOKING)
1st. latch switch COM-NO Closed Open
2nd. interlock relay
control switch
COM-NO Closed Open
Monitor switch COM-NC Open Closed
The circuits to the power transformer, fan motor and
turntable motor are cut off when the 1st. latch switch
and 2nd. interlock relay control switch are made open.
The oven lamp remains on even if the oven door is
opened after the cooking cycle has been interrupted,
because the relay RY1 stays closed. Shown in the
display is the remaining time.
6. MONITOR SWITCH CIRCUIT
The monitor switch is mechanically controlled by
oven door, and monitors the operation of the 1st. latch
switch and 2nd. interlock relay.
6-1 When the oven door is opened during or after the
cycle of a cooking program, the 1st. latch switch and
2nd. interlock relay control switch must open their
contacts first.
After that the contacts (COM-NC) of the monitor
switch can be closed.
6-2. When the oven door is closed, the contacts (COM-
NC) of the monitor switch must be opened. After that
the contacts of the 1st. latch switch and 2nd. interlock
relay control switch are closed.
6-3. When the oven door is opened and the contacts of the
1st. latch switch and 2nd. interlock relay remain
closed. The fuse F10A will blow, because the monitor
switch is closed and a short circuit is caused.
MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW
COOKING
When the microwave oven is preset for variable cooking
power, rated voltage is supplied to the power transformer
intermittently within a 32-second time base through the
relay contact which is coupled with the current-limiting
relay. The following levels of microwave power are given.
SETTING;
NOTE: The ON/ OFF time ratio does not exactly correspond
to the percentage of microwave power, because
approx. 3 seconds are needed for heating up the
magnetron filament.
POWER OUTPUT REDUCTION
After 100% power cooking mode is carried out for more
than 40 minutes, the power out-put is automatically reduced to 70%.
100P
32 sec. ON
70P
Approx. 70%
100%
24 sec. ON 8 sec. OFF
14 sec. OFF
20 sec. OFF
26 sec. OFF
50P Approx. 50%
18 sec. ON
30P
Approx. 30%
12 sec. ON
10P Approx. 10%
6 sec. ON
R-330H
5
FUNCTION OF IMPORTANT COMPONENTS
OVEN TEMPERATURE FUSE
The temperature fuse, located on the top of the oven
cavity, is designed to prevent damage to the oven by fire.
If the food load is overcooked, by either error in cook time
or defect in the control unit, the temperature fuse will open.
Under normal operation, the temperature fuse remains
closed. However, when abnormally high temperatures are
reached within the oven cavity, the temperature fuse will
open at 150˚C, causing the oven to shut down.
MAGNETRON TEMPERATURE FUSE
The temperature fuse located near the magnetron is
designed to prevent damage to the magnetron if an over
heated condition develops in the tube due to cooling fan
failure, obstructed air guide, dirty or blocked air intake, etc.
Under normal operation, the temperature fuse remains
closed. However, when abnormally high temperatures are
reached within the magnetron, the temperature fuse will
open at 150˚C causing the oven to shut down.
TURNTABLE MOTOR
The turntable motor drives the turntable roller assembly to
rotate the turntable.
FAN MOTOR
The fan motor drives a blade which draws external cool air.
This cool air is directed through the air vents surrounding
the magnetron and cools the magnetron. This air is channelled through the oven cavity to remove steam and
vapours given off from the heating foods. It is then exhausted through the exhausting air vents at the oven
cavity.
NOISE FILTER
The noise filter prevents the radio frequency interference
that might flow back in the power circuit.
DOOR OPEN MECHANISM
he door is opened by pushing the open button on the
control panel, refer to the Figure D-1.
When the open button is pushed, the open button pushes
up the switch lever, and then the switch lever pushes up
the latch head. The latch heads are moved upward and
released from latch hook. Now the door will open.
Figure D-1. Door Open Mechanism
1ST. LATCH SWITCH AND 2ND. INTERLOCK
RELAY CONTROL SWITCH
1. When the oven door is closed, the contacts (COM-NO)
must be closed.
2. When the oven door is opened, the contacts (COMNO) must be opened.
MONITOR SWITCH
1. When the oven door is closed, the contacts (COM-NC)
must be opened.
2. When the oven door is opened, the contacts (COMNC) must be closed.
3. If the oven door is opened and the contacts (COM-NO)
of the 1st. latch switch and 2nd. interlock relay fail to
open, the fuse F10A blows simultaneously with closing
the contacts (COM-NC) of the monitor switch.
CAUTION: BEFORE REPLACING A BLOWN FUSE F10A
TEST THE 1ST. LATCH SWITCH, 2ND.
INTERLOCK RELAY, MONITOR SWITCH
AND MONITOR RESISTOR FOR PROPER
OPERATION.
HIGH VOLTAGE FUSE
The high voltage fuse blows when the high voltage rectifier
or magnetron is shorted.
FUSE F10A
1. The fuse F10A blows when the contacts (COM-NO) of
the 1st. latch switch and 2nd. interlock relay remain
closed with the oven door open and when the monitor
switch closes.
2. If the wire harness or electrical components are shortcircuited, this fuse F10A blows to prevent an electric
shock or fire hazard.
Latch
Heads
Door
Switch Lever
Latch Hook
Monitor Switch
2nd. Interlock
Relay Control
Switch
1st Latch Switch
R-330H
6
SERVICING
WARNING TO SERVICE PERSONNEL
Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts
of the high voltage circuit will result in electrocution. High voltage capacitor, Power transformer, Magnetron, High
voltage rectifier assembly, High voltage fuse, High voltage harness.
REMEMBER TO CHECK 3D
1) Disconnect the supply.
2) Door opened, and wedged open.
3) Discharge the high voltage capacitor.
WARNING: AGAINST THE CHARGE OF THE
HIGH-VOLTAGE CAPACITOR
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, of
the connecting lead of the high-voltage rectifier)
against the chassis with the use of an insulated
screwdriver.
Sharp recommend that wherever possible fault-finding
is carried out with the supply disconnected. It may in,
some cases, be necessary to connect the supply after
the outer case has been removed, in this event carry
out 3D checks and then disconnect the leads to the
primary of the power transformer. Ensure that these
leads remain isolated from other components and the
oven chassis. (Use insulation tape if necessary.) When
the testing is completed carry out 3D checks and
reconnect the leads to the primary of the power transformer.
REMEMBER TO CHECK
4R
1) Reconnect all leads removed from components
during testing.
2) Replace the outer case (cabinet).
3) Reconnect the supply.
4) Run the oven. 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 microwave timer for two (2)
minutes. Set the power level to HIGH and push the
START button. When the two minutes has elapsed
(timer at zero) carefully check that the water is now hot.
If the water remains cold carry out
3D checks and reexamine the connections to the component being
tested.
When troubleshooting the microwave oven, it is helpful to
follow the Sequence of Operation in performing the
checks. Many of the possible causes of trouble will require
that a specific test be performed. These tests are given a
procedure letter which will be found in the "Test Procedure
"section.
When all service work is completed, and the oven is fully assembled, the microwave power output should be
checked and microwave leakage test should be carried out.
TROUBLESHOOTING GUIDE
IMPORTANT: If the oven becomes inoperative because
of a blown fuse F10A in the 1st. latch
switch - 2nd. interlock relay - monitor switch
circuit, check the 1st. latch switch, 2nd.
interlock relay and monitor switch before
replacing the fuse F10A.
R-330H
7
MAGNETRON
POWER TRANSFORMER
H.V. RECTIFIER ASSEMBLY
HIGH VOLTAGE CAPACITOR
1ST. LATCH SWITCH
2ND. INTERLOCK RELAY CONTROL
SWITCH
MONITOR SWITCH
TEMPERATURE FUSE (OVEN, MG)
FAN MOTOR
TURNTABLE MOTOR
FUSE F10A
TOUCH CONTROL PANEL
KEY UNIT
RELAY (RY-1, RY-2)
FOIL PATERN ON P.W.B.
POWER SUPPLY CORD
SHORTED WIRE HARNESS
OPENED WIRE HARNESS
OVEN LAMP
WALL OUTLET
MISADJUSTMENT SWITCH
HOME FUSE OR BREAKER
BLOCKED COOLING FAN
BLOCKED VENTILATION
NOISE FILTER
HIGH VOLTAGE FUSE
Home fuse blows when power
supply cord is plugged into
wall outlet.
FUSE F10A blows when
power supply cord is plugged
into wall outlet.
Display does not show anything when power supply cord
is plugged into wall outlet.
Display does not operate
properly when STOP/CLEAR
pad is touched.
Oven lamp does not light at
door opened. (Display appears.)
Oven does not start when the
START pad is touched. (Display appears)
Oven lamp does not light (Display appears.)
Fan motor does not operate.
(Display appears.)
Turntable motor assembly
does not operate. (Display
appears.)
Oven or any electrical parts
does not stop when cooking
time is 0 or STOP/CLEAR
pad is touched.
Oven seems to be operating
but little or no heat is produced
in oven load. (Microwave
power level is set at 100%)
Oven does not seems to be
operating properly when 70%,
50%, 30% or 10% is set.
(Oven operates properly at
100% and then the STOP/
CLEAR pad is touched the
oven stops.)
Oven goes into cook cycle
but shuts down before end
of cooking cycle.
TEST PROCEDURE
CK = Check / RE = Replace
ABCDEEEFG GHKLMN
RECK CK RE CK CKCK CK CK
IJ
CONDITION
PROBLEM
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
ON
CONDITION
OFF
CONDITION
R-330H
8
NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL
WHILE THE OVEN IS IN OPERATION.
CARRY OUT 3D CHECK.
Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.
To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron
filament terminals, the meter should show a reading of less than 1 ohm.
To test for short filament to anode condition, connect ohmmeter between one of the filament terminals
and the case of the magnetron (ground). This test should be indicated an infinite resistance. If a low
or zero resistance reading is obtained then the magnetron should be replaced.
MICROWAVE OUTPUT POWER (1 litre water load)
The following test procedure should be carried out with the microwave oven in a fully assembled
condition (outer case fitted). Microwave output power from the magnetron can be measured by IEC
test procedure, i.e. it can be measured by using water load how much it can be absorbed by the water
load. To measure the microwave output power in the microwave oven, the relation of calorie and watt
is used. When P(W) heating works for t(second), approximately P x t/4.187 calorie is generated. On
the other hand, if the temperature of the water with V(ml) rises ∆T (˚C) during this microwave heating
period, the calorie of the water is V x ∆T.
The formula is as follows;
P x t / 4.187 = V x ∆ T+ 0.55 x mc (T2-T0)/4.187P (W) = 4.187 x V x ∆T / t + 0.55 x mc (T2-T0)/t
Our condition for water load is as follows:
Room temperature (T0) ... around 20°CPower supply Voltage.............. Rated voltage
Water load..................................1000 g Initial temperature (T1) ...................... 10±1°C
Heating time.............................. 38 sec. Mass of container (mc) ......................... 330 g
T2............................ Final Temperature P = 110 x ∆T + 0.55 x mc (T2-T0)/38
Measuring condition:
1. Container
The water container must be a cylindrical borosilicate glass vessel having a maximum material
thickness of 3 mm and an outside diameter of approximately 190 mm.
2. Temperature of the oven and vessel
The oven and the empty vessel are at ambient temperature prior to the start of the test.
3. Temperature of the water
The initial temperature of the water is (10±1)˚C.
4. Select the initial and final water temperature so that the maximum difference between the final
water temperature and the ambient temperature is 5˚C.
5. Select stirring devices and measuring instruments in order to minimize addition or removal of heat.
6. The graduation of the thermometer must be scaled by 0.1˚C at minimum and an accurate
thermometer.
7. The water load must be (1000±5) g.
8. “t” is measured while the microwave generator is operating at full power. Magnetron filament heatup time is not included.
NOTE: The operation time of the microwave oven is “t + 3” sec. 3 sec. is magnetron filament heat-
up time.
Measuring method:
1. Measure the initial temperature of the water before the water is added to the vessel.
(Example: The initial temperature T1 = 11˚C)
2. Add the 1 litre water to the vessel.
3. Place the load on the centre of the shelf.
4. Operate the microwave oven at HIGH for the temperature of the water rises by a value ∆ T of
10 ˚C.
5. Stir the water to equalize temperature throughout the vessel.
6. Measure the final water temperature. (Example: The final temperature T2 = 21°C)
7. Calculate the microwave power output P in watts from above formula.
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
A MAGNETRON TEST
R-330H
9
Room temperature .................. To = 21˚C Initial temperature................. T1 = 11°C
Temperature after (38 + 3) = 41 sec. ................................................................ T2 = 21°C
Temperature difference Cold-Warm .............................................................. ∆T1 = 10°C
Measured output power
The equation is “P = 110 x ∆T” ........................................... P = 110 x 10°C = 1100 Watts
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
JUDGEMENT: The measured output power should be at least ± 15 % of the rated output power.
CAUTION: 1°C CORRESPONDS TO 110 WATTS REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
1000g
1000g
1000g
T1˚C
T2˚C
Heat up for 41 sec.
B POWER TRANSFORMER TEST
WARNING: High voltages and large currents are present at the secondary winding and filament
winding of the power transformer. It is very dangerous to work near this part when
the oven is on. NEVER make any voltage measurements of the high-voltage
circuits, including the magnetron filament.
CARRY OUT 3D CHECKS.
Disconnect the leads to the primary winding of the power transformer. Disconnect the filament and
secondary winding connections from the rest of the HV circuitry. Using an ohmmeter, set on a low
range, it is possible to check the continuity of all three windings. The following readings should be
obtained:
a. Primary winding ....................approx. 1.9 Ω
b. Secondary winding ...............approx. 104 Ω
c. Filament winding...................less than 1Ω
If the reading obtained are not stated as above, then the power transformer is probably faulty and
should be replaced.
CARRY OUT 4R CHECKS.
C HIGH VOLTAGE RECTIFIER ASSEMBLY TEST
HIGH VOLTAGE RECTIFIER TEST
CARRY OUT 3D CHECKS.
Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested
using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal B+C of the
high voltage rectifier and note the reading obtained. Reverse the meter leads and note this second
reading. The normal resistance is infinite in one direction and more than 100 kΩ in the other direction.
CARRY OUT 4R CHECKS.
NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF
THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BECAUSE
OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.
B
C
HIGH VOLTAGE RECTIFIER
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