Sharp R-450H User manual

R-450H
35
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 ...................................................................................................................................................... 6
TEST PROCEDURE ......................................................................................................................................... 8
TOUCH CONTROL PANEL ............................................................................................................................. 13
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ........................................................... 18
MICROWAVE MEASUREMENT .................................................................................................................... 24
WIRING DIAGRAM ......................................................................................................................................... 25
PICTORIAL DIAGRAM ................................................................................................................................... 26
POWER UNIT CIRCUIT .................................................................................................................................. 27
CPU UNIT CIRCUIT ........................................................................................................................................ 28
PRINTED WIRING BOARD ............................................................................................................................. 29
PARTS LIST ................................................................................................................................................... 30
S7304R450HPJ/
MICROWAVE OVEN
MODEL R-450H
In interests of user-safety the oven should be restored to its original
condition and only parts identical to those specified should be used.
SHARP CORPORATION
SERVICE MANUAL

36
R-450H

R-450H
1
SERVICE MANUAL
MICROWAVE OVEN
R-450H
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 micro-
wave 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

2
R-450H
PRODUCT SPECIFICATIONS
ITEM DESCRIPTION
Power Requirements 230 - 240 Volts
50 Hertz
Single phase, 3 wire earthed
Power Consumption 1.65 kW
Power Output 1200 watts nominal of RF microwave energy (IEC Test Procedure)
Operating frequency 2450 MHz
Case Dimensions Width 550 mm
Height 315 mm
Depth 446 mm
Turntable diameter 360mm
Control Complement Touch Control System
Clock ( 1:00 - 12:59)
Timer (0 - 99 minutes 99 seconds)
Microwave Power for Variable Cooking
Repetition Rate;
HIGH ............................................... Full power throughout the cooking time
MEDIUM HIGH .................................................. approx. 70% of Full Power
MEDIUM ............................................................. approx. 50% of Full Power
MEDIUM LOW .................................................... approx. 30% of Full Power
LOW .................................................................... approx. 10% of Full Power
HELP pad
INFOMATION COOK pads
CONVENIENCE MEALS pads
EXPRESS MENUS pads
REHEAT MENU pads
MORE, LESS pads
NUMBER pads
POWER LEVEL pad
CLOCK pad
TIMER pad
STOP/CLEAR pad
INSTANT COOK/START pad
Weight Approx. 19 kg
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-450H
3
APPEARANCE VIEW
1. Ventilation openings
2. Oven lamp
3. Door hinges
4. Door safety latches
5. See through door
6. Door seals and sealing
surfaces
7. Coupling
8. Door open button
9. Touch control panel
10.Digital readout
11.Waveguide cover
12.Power supply cord
13.Rating label
14.Menu label
15.Turntable
16.Roller stay
10
3
4
2
713
5
614
4
11
8
16
9
12
15 1
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.
DEFROST COOK HELP
Indicator
Display
INFORMATION COOK PADS
Press to select Information
Cook mode.
CONVENIENCE MEALS PADS
Press to select Convenience
Meals menus.
MORE( ), LESS ( ) PADS
Press to increase/decrease
the time in one minute incre-
ments during cooking or to
alter the cooking result for
automatic operations.
NUMBER PADS
Press to enter cooking times,
clock time, weight or quantity
of food.
POWER LEVEL PAD
Press to select microwave
power setting.If not pressed,
HIGH is auto-matically selec-
ted.
STOP/CLEAR PAD
Press to clear during pro-
gramming.
Press once to stop operation
of oven during cooking;
press twice to cancel cook-
ing programme.
EXPRESS MENUS PADS
Press to select "Express Me-
nus" menus.
REHEAT MENU PADS
Press to select a reheat menu.
HELP PAD
Press to select auto start,
child lock or demonstration
mode.Press to display preset
menu cooking information.
TIMER PAD
Press to set Timer.
CLOCK PAD
Press to set Clock
I
NSTANT COOK/START PAD-
Press to start oven after set-ting
programmes.Press once to cook
for 1 min-ute on HIGH or in-
crease in 1 minute increments
each time this pad is pressed
during cooking.

4
R-450H
OPERATION SEQUENCE
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 first. 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.
VARIABLE 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 relay (RY2). The
following levels of microwave power are given.
SETTING;
OFF CONDITION
Closing the door activates all door interlock switches
(1st. latch switch, 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 SHARP, MICRO-WAVE and OVEN.
2. To set any programs 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
pads 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
(off condition). 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,
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 more than
40 minutes, the power output is automatically reduced to
70%.
HIGH
32 sec. ON
MEDIUM HIGH Approx. 70%
24 sec. ON 8 sec. OFF
14 sec. OFF
20 sec. OFF
26 sec. OFF
MEDIUM Approx. 50%
18 sec. ON
MEDIUM LOW Approx. 30%
12 sec. ON
LOW Approx. 10%
6 sec. ON

R-450H
5
Figure D-1. Door Open Mechanism
1ST. LATCH SWITCH AND 2ND. INTERLOCK RE-
LAY 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 (COM-
NO) 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 (COM-
NC) 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 AND MONITOR
SWITCH FOR PROPER OPERATION. (RE-
FER TO CHAPTER "TEST PROCEDURE".)
FUSE (F10A)
1. If the wire harness or electrical components are short-
circuited, this fuse blows to prevent an electric shock or
fire hazard.
2. The fuse also blows when 1st. latch switch and 2nd.
interlock relay remains closed with the oven door open
and when the monitor switch closes.
HIGH VOLTAGE FUSE 0.75A
The high voltage fuse blows when the high voltage rectifier
or magnetron is shorted.
FUNCTION OF IMPORTANT COMPONENTS
DOOR OPEN MECHANISM
The door can be opened by pushing the door open button
on the control panel. When the door open button is
pushed, the latch lever is moved upward, operating the
latch head. The latch head is moved upward, and released
from latch hook. Now the door can be opened.
THERMAL CUT-OUT 145˚C (OVEN)
The thermal cut-out located on the top of the oven cavity
is designed to prevent damage to the oven if the foods in
the oven catch fire due to over heating produced by
improper setting of cook time or failure of control unit.
Under normal operation, the oven thermal cut-out remains
closed. However, when abnormally high temperature is
reached within the oven cavity, the oven thermal cut-out
will open at 145˚C, causing the oven to shut down. The
defective thermal cut-out must be replaced with new one.
THERMAL CUT-OUT 145˚C (MAGNETRON)
The thermal cut-out located near the magnetron is de-
signed 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 thermal cut-out remains
closed. However, when abnormally high temperatures are
reached within the magnetron, the thermal cut-out will
open at 145˚C causing the oven to shut down. The
defective thermal cut-out must be replaced with new one.
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 vanes surrounding
the magnetron and cools the magnetron. This air is chan-
nelled through the oven cavity to remove steam and
vapours given off from the heating foods. It is then ex-
hausted 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.
Latch Hook
1st. Latch
Switch
Monitor
Switch
Switch
Lever
Latch
Heads
Door
2nd. Interlock
Relay Control
Switch

6
R-450H
SERVICING
Microwave ovens contain circuitry capable of pro-
ducing very high voltage and current, contact with
any part of the high voltage circuit will result in
electrocution. High voltage capacitor, Power trans-
former, Magnetron, High voltage rectifier assem-
bly, High voltage fuse, High voltage harness.
REMEMBER TO CHECK 3D
1) Disconnect the supply.
2) Door opened, and wedged open.
3) Discharge 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 trans-
former.
WARNING TO SERVICE PERSONNEL
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 re-
examine 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 microwave leakage test should be carried out.
TROUBLESHOOTING GUIDE
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.
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-450H
7
CK = Check / RE = Replace
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 HIGH)
Oven does not seems to be
operating properly when
MEDIUM HIGH, MEDIUM,
MEDIUM LOW or LOW is set.
(Oven operates properly at HIGH
and when the STOP/CLEAR pad
is touched the oven stops.)
Oven goes into cook cycle but
shuts down before end of
cooking cycle.
Oven stops as soon as when
the START pad is touched.
MAGNETRON
POWER TRANSFORMER
H.V. RECTIFIER ASSEMBLY
HIGH VOLTAGE CAPACITOR
1ST. LATCH SWITCH
2ND. N D. INTERLOCK RELAY
CONTROL SWITCH
MONITOR SWITCH
NOISE FILTER
THERMAL CUT-OUT (MAGNETRON)
THERMAL CUT-OUT (OVEN)
FAN MOTOR
TURNTABLE MOTOR
FUSE F10A
HIGH VOLTAGE FUSE
TOUCH CONTROL PANEL
KEY UNIT
RELAY (RY-1, RY-2)
FOIL PATERN ON P.W.B.
POWER SUPPLY CORD
OVEN LAMP OR SOCKET
SHORTED WIRE HARNESS
OPENED WIRE HARNESS
WALL OUTLET
HOME FUSE OR BREAKER
WRONG OPERATION
MISADJUSTMENT SWITCH
BLOCKED COOLING FAN
BLOCKED VENTILATION OPENING
ABCDEEEFGGHHIJKLMN RE RE CK CK CK CK CK CK CK CK
POSSIBLE CAUSE
AND
DEFECTIVE PARTS
TEST PROCEDURE
PROBLEM
CONDITION
OFF
CONDITION
ON
CONDITION

8
R-450H
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
AMAGNETRON TEST
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 circuit 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)/ 4.187 P (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 .............................. 35 sec. Mass of container (mc) ......................... 330 g
T2 ............................ Final Temperature P = 120 x ∆T + 0.55 x mc (T2-T0)/35
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 heat-
up 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.

R-450H
9
DHIGH VOLTAGE CAPACITOR TEST
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
Room temperature .................. To = 21˚C Initial temperature ................. T1 = 11°C
Temperature after (35 + 3) = 38 sec. ................................................................ T2 = 21°C
Temperature difference Cold-Warm .............................................................. ∆T1 = 10°C
Measured output power
The equation is “P = 120 x ∆T” ........................................... P = 120 x 10°C = 1200 Watts
Heat up for 38 sec.
1000g
1000g
1000g
T1˚CT2˚C
BPOWER 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. 1.0 Ω
b. Secondary winding .............. approx. 84 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.
CHIGH 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 kΩin 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.
BC
HIGH VOLTAGE RECTIFIER
JUDGEMENT: The measured output power should be at least ±15 % of the rated output power.
CAUTION: 1°C CORRESPONDS TO 120 WATTS REPEAT MEASUREMENT IF THE POWER IS
INSUFFICIENT.
CARRY OUT 3D CHECKS.
A. Isolate the high voltage capacitor from the circuit.

10
R-450H
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
B. Continuity check must be carried out with measuring instrument which is set to the highest resistance
range.
C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10MΩafter
it has been charged.
D. A short-circuited capacitor shows continuity all the time.
E. An open capacitor constantly shows a resistance about 10 MΩbecause of its internal 10MΩresistance.
F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
G. The resistance across all the terminals and the chassis must be infinite when the capacitor is normal.
If incorrect reading are obtained, the high voltage capacitor must be replaced.
CARRY OUT 4R CHECKS.
ESWITCH TEST
CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the
following table.
Table: Terminal Connection of Switch
Plunger Operation COM to NO COM to NC COM; Common terminal
Released Open circuit Short circuit NO; Normally open terminal
Depressed Short circuit Open circuit NC; Normally close terminal
If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.
CARRY OUT 4R CHECKS.
FNOISE FILTER TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the noise filter.
Using an ohmmeter, check between the terminals as de-
scribed in the following table.
MEASURING POINT INDICATION OF OHMMETER
Between N and L Open circuit
Between terminal N and WHITE Short circuit
Between terminal L and RED Short circuit
If incorrect readings are obtained, replace the noise filter unit.
CARRY OUT 4R CHECKS.
CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of the thermal cut-out. Then using an ohmmeter, make a
continuity test across the two terminals as described in the table below.
CARRY OUT 4R CHECKS.
Table: Thermal cut-out Test
Temperature of "ON" Temperature of "OFF" Indication of ohmmeter
Parts Name condition (closed circuit) (˚C) condition (open circuit) (˚C) (When room temperature
is approx. 20˚C)
Thermal cut-out 145˚C This is not resetable type. Above 145˚C Closed circuit.
If incorrect readings are obtained, replace the thermal cut-out.
An open circuit thermal cut-out 145˚C (MAGNETRON) indicates that the magnetron has over-
heated, this may be due to restricted ventilation, cooling fan failure or a fault condition within the
magnetron or HV circuit.
An open circuit thermal cut-out 145˚C (OVEN) indicates that the foods in the oven may catch fire,
this may be due to over heating produced by improper setting of the cooking time or failure of the
control panel.
G THERMAL CUT-OUT TEST
FUSE
F10A
NOISE SUPPRESSION COIL
NL
0.0022µ/AC 250V 0.0022µ/AC 250V
LINE CROSS CAPACITOR
0.068µ/AC250V
WHT RED

R-450H
11
KTOUCH CONTROL PANEL ASSEMBLY TEST
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
HMOTOR WINDING TEST
CARRY OUT 3D CHECKS.
Disconnect the leads from the motor.
Using an ohmmeter, check the resistance between the two terminals as described in the table below.
Table: Resistance of Motor
Motors Resistance
Fan motor Approximately 250 Ω
Turntable motor Approximately 14.5 kΩ
If incorrect readings are obtained, replace the motor.
CARRY OUT 4R CHECKS.
CARRY OUT 3D CHECKS.
1. If the fuse F10A is blown, there could be shorts or ground in electrical parts or wire harness.
Check them and replace the defective parts or repair the wire harness.
2. If the fuse F10A is blown when the door is opened, check the 1st. latch switch, 2nd. interlock
relay and monitor switch.
If the fuse F10A is blown by incorrect door switching replace the defective switch(s) and the
fuse F10A.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE FUSE F10A WITH THE CORRECT VALUE REPLACEMENT
IBLOWN FUSE F10A
The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore,
unlike conventional microwave ovens, proper maintenance cannot be performed with only a
voltmeter and ohmmeter. In this service manual, the touch control panel assembly is divided into two
units, Control Unit and Key Unit, and also the Control Unit is divided into two units, CPU Unit and
Power Unit, and troubleshooting by unit replacement is described according to the symptoms
indicated.
1. Key Unit. Note: Check key unit ribbon connection before replacement.
The following symptoms indicate a defective key unit. Replace the key unit.
a) When touching the pads, a certain pad produces no signal at all.
b) When touching a number pad, two figures or more are displayed.
c) When touching the pads, sometimes a pad produces no signal.
2. Control Unit.
The following symptoms indicate a defective control unit. Before replacing the control unit, perform
the Key unit test (Procedure L) to determine if control unit is faulty.
2-1 In connection with pads.
a) When touching the pads, a certain group of pads do not produce a signal.
b) When touching the pads, no pads produce a signal.
2-2 In connection with indicators.
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
JHIGH VOLTAGE FUSE TEST
CARRY OUT 3D CHECKS.
If the high voltage fuse is blown, there could be a short in the high voltage rectifier or the magnetron.
Check them and replace the defective parts and high voltage fuse.
CARRY OUT 4R CHECKS.
CAUTION: ONLY REPLACE THE HIGH VOLTAGE FUSE WITH THE CORRECT VALUE RE-
PLACEMENT

12
R-450H
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up; or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
2-3 Other possible troubles 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.
LKEY UNIT TEST
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable
is making good contact, verify that the door 2nd. interlock relay control switch operates properly; that
is the contacts are closed when the door is closed and open when the door is open. If the 2nd. interlock
relay control switch is good, disconnect the flat ribbon cable that connects the key unit to the control
unit and make sure the 2nd. interlock relay control switch is closed (either close the door or short the
2nd. interlock relay control switch connector). Use the key unit matrix indicated on the control panel
schematic and place a jumper wire between the pins that correspond to the STOP/CLEAR pad
making momentary contact. If the control unit responds by clearing with a beep the key unit is faulty
and must be replaced. If the control unit does not respond, it is faulty and must be replaced.
If a specific pad does not respond, the above method may be used (after clearing the control unit) to
determine if the control unit or key pad is at fault.
CARRY OUT 3D CHECKS.
MRELAY TEST
Remove the outer case and check voltage between Pin No 1 of the 2-pin connector (A) and the
common terminal of the relay RY1 on the power unit with an A.C. voltmeter. The meter should indicate
230 - 240 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,
control unit is defective.
RELAY SYMBOL OPERATIONAL VOLTAGE CONNECTED COMPONENTS
RY1 APPROX. 25.0V D.C. Oven lamp / Turntable motor / Cooling fan motor
RY2 APPROX. 24.0V D.C. Power transformer
CARRY OUT 4R CHECKS.
N PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary
on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
Problem: POWER ON, indicator does not light up.
CARRY OUT 3D CHECKS.
G 1 G 2 G 3 G 4 G 5 G 6 G 7 G 8
G 9
G10
G11
G12
G13
G14
5
0
4
9
3
8
2
7
1
6
DINNER
PLATE
VEGETABLES
EASY
DEFROST
PASTA
MEAL
PIZZA
EXPRESS
MEAL
FROZEN
DINNER
PIE
EXPRESS
COOK
CASSEROLE
SOUP
INSTANT COOK
START
LESS
TIMER
POWER
LEVEL
RICE/
PASTA
CLOCK
MORE
BEVERAGE
EXPRESS
DEFROST
STOP
CLEAR HELP

R-450H
13
TEST PROCEDURES
PROCEDURE
LETTER COMPONENT TEST
STEPS OCCURRENCE CAUSE OR CORRECTION
1 The rated AC voltage is not present between Check supply voltage and oven power cord.
Pin No. 1 of the 2-pin connector (A) and the
common terminal of the relay RY1.
2 The rated AC voltage is present to primary Low voltage transformer or secondary circuit defective.
side of low voltage transformer. Check and repair.
3Only pattern at "a" is broken. *Insert jumper wire J1 and solder.
4 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d".
NOTE: *At the time of making these repairs,
make a visual inspection of the varistor.
Check for burned damage and exam-
ine the transformer with a tester for the
presence of layer short-circuit (check
the primary coil resistance). If any ab-
normal condition is detected, replace
the defective parts.
CARRY OUT 4R CHECKS.
T1
AC
VRS1
QKITPB026MRE0
OMIF DU
CN - A
(J1)
abc
d
12
XA
VH
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
The touch control section consists of the following units.
(1) Key Unit
(2) Control Unit (The Control Unit consists of Power
Unit and LSI Unit).
The principal functions of these units and the signals
communicated among them are explained below.
Key Unit
The key unit is composed of a matrix, signals generated
in the LSI are sent to the key unit through P00-P07.
When a key pad is touched, a signal is completed through
the key unit and passed back to the LSI through P14-P17,
AIN6 and AIN7 to perform the function that was re-
quested.
Control Unit
Control unit consists of LSI, reset circuit, indicator circuit,
power source circuit, relay circuit, buzzer circuit, synchro-
nizing signal circuit and back light circuit.
1) Reset Circuit
This circuit generates a signal which resets the LSI to
the initial state when power is supplied.
2) Indicator Circuit
This circuit consists of 40 segments and 16 common
electrodes using a Liquid Crystal Display.
3) Power Source Circuit
This circuit generates voltages necessary in the con-
trol unit from the AC line voltage.
In addition, the synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
Symbol Voltage Application
VC -5V LSI(IC1)
4) Relay Circuit
A circuit to drive the magnetron, fan motor, turntable
motor and light the oven lamp.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion
sound).
6) Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to compose a basic standard time in the clock
circuit.
It accompanies a very small error because it works on
commercial frequency.
7) 2nd. Interlock Relay Control Switch
A switch to “tell” the LSI if the door is open or closed.
8) Back Light Circuit
A circuit to drive the back light (Light emitting diodes
LD10-LD15).

14
R-450H
LSI
The I/O signal of the LSI is detailed in the following table.
Pin No. Signal I/O Description
1COM5 OUT Common data signal : COM11. Connected to LCD signal COM11.
2COM4 OUT Common data signal : COM12. Connected to LCD signal COM12.
3COM3 OUT Common data signal : COM13. Connected to LCD signal COM13.
4COM2 OUT Common data signal : COM14. Connected to LCD signal COM14.
5COM1 OUT Common data signal : COM15. Connected to LCD signal COM15.
6COM0 OUT Common data signal : COM16. Connected to LCD signal COM16.
7-10 VL1-VL4 IN Power source voltage input terminal.
Standard voltage for LCD.
11 VL5 IN Power source voltage input terminal.
Standard voltage for LCD. Connected to GND.
12-14 C3-C1 IN Terminal not used.
15 VLIN IN Terminal not used.
16 VREG OUT Terminal not used.
17 NC _Terminal not used.
18 VSS IN Power source voltage : -5.0V.
The power source voltage to the LSI is input to VSS terminal. Connected to VC.
19-21 P27-P25 OUT Terminal not used.
22-26 P24-P20 IN Terminal not used.
27 P47 IN To input signal which communicates the door open/close information to LSI.
Door close "H" level signal (0V). Door open "L" level signal (-5V).
28 P46 OUT Terminal not used.
29 P45 OUT Oven lamp, fan motor and turntable motor driving signal.
To turn on and off shut off relay (RY1). The
square waveform voltage is delivered to the RY1
driving circuit and RY2 control circuit.
30 P44 OUT Magnetron high-voltage circuit driving signal.
To turn on and off the cook relay (RY2). The
signals holds "L" level during microwave cook-
ing and "H" level while not cooking. In other
cooking modes (variable cooking) the signal
turns to "H" level and "L" level in repetition
according to the power level.
(ON and OFF times for other power level.)
31 P43 _Terminal not used.
32 CNTR0 OUT Signal to sound buzzer (2.0 kHz).
A: key touch sound.
B: Completion sound.
33 P41 OUT Terminal not used.
34 INT0 IN Signal synchronized with commercial power source frequency.
This is the basic timing for time processing of LSI.
35 P07 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16 and P17
terminal while one of G1 line keys on key matrix is touched.
36 P06 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16 and P17
terminal while one of G2 line keys on key matrix is touched.
20.0 msec.
During cooking
H : GND
L : -5V
100
PERCENT
70
PERCENT
H : GND
L : -5V
H : GND
L : -5V
ON
ON
OFF
OFF OFF
24 sec.
8 sec.
A
B
0.1 sec.
2.0 sec.
H : GND
L : -5V
H : GND
L : -5V
20.0 msec.
H : GND
L : -5V

R-450H
15
37 P05 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16 and P17
terminal while one of G3 line keys on key matrix is touched.
38 P04 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16, P17 and
AIN6 terminal while one of G4 line keys on key matrix is touched.
39 P03 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16 and P17
terminal while one of G5 line keys on key matrix is touched.
40 P02 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16 and P17
terminal while one of G6 line keys on key matrix is touched.
41 P01 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16 and P17
terminal while one of G7 line keys on key matrix is touched.
42 P00 OUT Key strobe signal.
Signal applied to touch-key section. A pulse signal is input to AIN7, P14, P15, P16 and P17
terminal while one of G8 line keys on key matrix is touched.
43 P17 IN Signal coming from touch key.
When either G9 line on key matrix is touched, a corresponding signal out of P00-P07 will be
input into P17. When no key is touched, the signal is held at "H" level.
44 P16 IN Signal similar to P17.
When either G10 line on key matrix is touched, a corresponding signal will be input into P16.
45 P15 IN Signal similar to P17.
When either G11 line on key matrix is touched, a corresponding signal will be input into P15.
46 P14 IN Signal similar to P17.
When either G12 line on key matrix is touched, a corresponding signal will be input into P14.
47 AIN7 IN Signal similar to P17.
When either G13 line on key matrix is touched, a corresponding signal will be input into AIN7.
48 AIN6 IN Input terminal to judge the model.
The signal out of P04 will be input into AIN6 through G4 line on key matrix. The LSI will judge
the model by this signal.
49 AIN5 IN Connected to VC through resistor.
50 AIN4 IN Connected to VC through resistor.
51 RESET IN Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied. Temporarily set "L"
level the moment power is applied, at this time the LSI is reset. Thereafter set at "H" level
52 NC _Terminal not used.
53 XCOUT OUT Terminal not used.
54 XCIN IN Connected to VC.
55 NC _Terminal not used.
56 VCC IN Power source voltage: GND(0V).
The power source voltage to drive LSI is input to VCC terminal.
57 OSCSEL IN Connected to VC(-5V).
58 XOUT OUT Internal clock oscillation output.
Output to control oscillation input of XIN.
59 VSS IN Power source voltage: -5.0V.
The power source voltage to the LSI is input to VSS terminal. Connected to VC.
60 NC _Terminal not used.
61 XIN IN Internal clock oscillation frequency control input setting.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit with respect
to XOUT terminal.
62 NC _ Terminal not used.
63-66 AIN3-AIN0 IN Terminal to change cooking input according to the Model.
By using the A/D converter contained in the LSI, DC voltage in accordance with the Model
in operation is applied to set up its cooking constant.
67 COM8 OUT Common data signal : COM8. Connected to LCD signal COM8.
Pin No. Signal I/O Description

16
R-450H
Pin No. Signal I/O Description
.68 COM9 OUT Common data signal : COM7. Connected to LCD signal COM7.
69 COM10 OUT Common data signal : COM6. Connected to LCD signal COM6.
70 COM11 OUT Common data signal : COM5. Connected to LCD signal COM5.
71 COM12 OUT Common data signal : COM4. Connected to LCD signal COM4.
72 COM13 OUT Common data signal : COM3. Connected to LCD signal COM3.
73 COM14 OUT Common data signal : COM2. Connected to LCD signal COM2.
74 COM15 OUT Common data signal : COM1. Connected to LCD signal COM1.
75-102 SEG67-SEG40 OUT Terminal not used.
103-142 SEG39-SEG0 OUT Segment data signal.
Connected to LCD.
The relation between signals and LCD are as follows:
LSI signal (Pin No.) LCD segment LSI signal (Pin No.) LCD segment
SEG 39 (103) ................................. SEG 1 SEG 19 (123) ............................... SEG 21
SEG 38 (104) ................................. SEG 2 SEG 18 (124) ............................... SEG 22
SEG 37 (105) ................................. SEG 3 SEG 17 (125) ............................... SEG 23
SEG 36 (106) ................................. SEG 4 SEG 16 (126) ............................... SEG 24
SEG 35 (107) ................................. SEG 5 SEG 15 (127) ............................... SEG 25
SEG 34 (108) ................................. SEG 6 SEG 14 (128) ............................... SEG 26
SEG 33 (109) ................................. SEG 7 SEG 13 (129) ............................... SEG 27
SEG 32 (110) ................................. SEG 8 SEG 12 (130) ............................... SEG 28
SEG 31 (111) ................................. SEG 9 SEG 11 (131) ............................... SEG 29
SEG 30 (112) ................................. SEG 10 SEG 10 (132) ............................... SEG 30
SEG 29 (113) ................................. SEG 11 SEG 9 (133) ............................... SEG 31
SEG 28 (114) ................................. SEG 12 SEG 8 (134) ............................... SEG 32
SEG 27 (115) ................................. SEG 13 SEG 7 (135) ............................... SEG 33
SEG 26 (116) ................................. SEG 14 SEG 6 (136) ............................... SEG 34
SEG 25 (117) ................................. SEG 15 SEG 5 (137) ............................... SEG 35
SEG 24 (118) ................................. SEG 16 SEG 4 (138) ............................... SEG 36
SEG 23 (119) ................................. SEG 17 SEG 3 (139) ............................... SEG 37
SEG 22 (120) ................................. SEG 18 SEG 2 (140) ............................... SEG 38
SEG 21 (121) ................................. SEG 19 SEG 1 (141) ............................... SEG 39
SEG 20 (122) ................................. SEG 20 SEG 0 (142) ............................... SEG 40
143 COM7 OUT Common data signal : COM9. Connected to LCD signal COM9.
144 COM6 OUT Common data signal : COM10. Connected to LCD signal COM10.

R-450H
17
1. Precautions for Handling Electronic Components
This unit uses CMOS LSI in the integral part of the
circuits. When handling these parts, the following
precautions should be strictly followed. CMOS LSI
have extremely high impedance at its input and output
terminals. For this reason, it is easily influenced by the
surrounding high voltage power source, static electric-
ity charge in clothes, etc. and sometimes it is not fully
protected by the built-in protection circuit.
In order to protect CMOS LSI.
1) When storing and transporting, thoroughly wrap them
in aluminium foil. Also wrap all PW boards containing
them in aluminium foil.
2) When soldering, ground the technician as shown in the
figure and use grounded soldering iron and work table.
approx. 1M ohm
TOUCH CONTROL PANEL SERVICING
(sensor-related ones included) of the touch control
panel while keeping it connected to the oven.
B. On some models, the power supply cord between the
touch control panel and the oven proper is long enough
that they may be separated from each other. For those
models, therefore, it is possible to check and repair the
controls of the touch control panel while keeping it
apart from the oven proper; in this case you must short
both ends of the door sensing switch (on PWB) of the
touch control panel with a jumper, which brings about
an operational state that is equivalent to the oven door
being closed. As for the sensor-related controls of the
touch control panel, checking them is possible if dummy
resistor(s) with resistance equal to that of the controls
are used.
(2) Servicing the touch control panel with power supply
from an external power source:
Disconnect the touch control panel completely from
the oven proper, and short both ends of the door
sensing switch (on PWB) of the touch control panel,
which brings about an operational state that is
equivalent to the oven door being closed. Connect an
external power source to the power input terminal of
the touch control panel, then it is possible to check and
repair the controls of the touch control panel it is also
possible to check the sensor-related controls of the
touch control panel by using the dummy resistor(s).
4. Servicing Tools
Tools required to service the touch control panel
assembly.
1) Soldering iron: 30W
(It is recommended to use a soldering iron with a
grounding terminal.)
2) Oscilloscope: Single beam, frequency range: DC-
10MHz type or more advanced model.
3) Others: Hand tools
5. Other Precautions
1) Before turning on the power source of the control unit,
remove the aluminium foil applied for preventing static
electricity.
2) Connect the connectors of the key unit to the control
unit being sure that the lead wires are not twisted.
3) After aluminium foil is removed, be careful that abnor-
mal voltage due to static electricity etc. is not applied
to the input or output terminals.
4) Attach connectors, electrolytic capacitors, etc. to PWB,
making sure that all connections are tight.
5) Be sure to use specified components where high
precision is required.
2. Shapes of Electronic Components
ECB
ECB
3. Servicing of Touch Control Panel
We describe the procedures to permit servicing of the
touch control panel of the microwave oven and the
precautions you must take when doing so. To perform
the servicing, power to the touch control panel is
available either from the power line of the oven itself or
from an external power source.
(1) Servicing the touch control panel with power sup-
ply of the oven:
CAUTION:
THE HIGH VOLTAGE TRANSFORMER OF THE MI-
CROWAVE OVEN IS STILL LIVE DURING SERVIC-
ING PRESENTS A HAZARD.
Therefore, when checking the performance of the
touch control panel, put the outer cabinet on the oven
to avoid touching the high voltage transformer, or
unplug the primary terminal (connector) of the high
voltage transformer to turn it off; the end of such
connector must be insulated with an insulating tape.
After servicing, be sure to replace the leads to their
original locations.
A. On some models, the power supply cord between the
touch control panel and the oven itself is so short that
the two can’t be separated.
For those models, check and repair all the controls
Transistor
KRC243M
Transistor
2SB1238

18
R-450H
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE
WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below before
operating the oven.
1. Disconnect the oven from the power supply.
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. Visually check the door and cavity face plate for damage
(dents, cracks, signs of arcing etc.).
Carry out any remedial work that is necessary before
operating the oven.
Do not operate the oven if any of the following conditions
exist;
1. Door does not close firmly.
2. Door hinge, support or latch hook is damaged.
3. The door gasket or seal or damaged.
4. The door is bent or warped.
5. There are defective parts in the door interlock system.
6. There are defective parts in the microwave generating
and transmission assembly.
7. There is visible damage to the oven.
Do not operate the oven:
1. Without the RF gasket (Magnetron).
2. If the wave guide or oven cavity are not intact.
3. If the door is not closed.
4. If the outer case (cabinet) is not fitted.
Please refer to ‘OVEN PARTS, CABINET PARTS, CONTROL PANEL PARTS, DOOR PARTS’, when carrying out any
of the following removal procedures:
WARNING FOR WIRING
To prevent an electric shock, take the following
manners.
1. Before wiring,
1) Disconnect the power supply.
2) Open the door and wedge the door open.
3) Discharge the high voltage capacitor and wait for
60 seconds.
2. Don't let the wire leads touch to the following parts;
1) High voltage parts:
Magnetron, High voltage transformer, High
voltage capacitor, High voltage rectifier assembly
and High voltage fuse.
2) Hot parts:
Oven lamp, Magnetron, High voltage transformer
and Oven cavity.
3) Sharp edge:
Bottom plate, Oven cavity, Waveguide flange,
Chassis support and other metallic plate.
4) Movable parts (to prevent a fault)
Fan blade, Fan motor, Switch, Switch lever,
Open button.
3. Do not catch the wire leads in the outer case cabinet.
4. Insert the positive lock connector certainly until its
pin is locked. And make sure that the wire leads
should not come off even if the wire leads is pulled.
5. To prevent an error function, connect the wire leads
correctly, referring to the Pictorial Diagram.
To remove the outer case, proceed as follows.
1. Disconnect oven from power supply.
2. Open the oven door and wedge it open.
3. Remove the four (4) screws from rear and along the
side edge of case.
4. Slide the entire case back about 1 inch (3 cm) to free
it from retaining clips on the cavity face plate.
5. Lift the entire case from the oven.
OUTER CASE REMOVAL
6. Discharge the H.V. capacitor before carrying out any
further work.
7. Do not operate the oven with the outer case removed.
N.B.; Step 1,2 and 6 form the basis of the 3D checks.
CAUTION: DISCHARGE HIGH VOLTAGE CAPACITOR
BEFORE TOUCHING ANY OVEN COMPO-
NENTS OR WIRING.
1. CARRY OUT 3D CHECKS.
2. Disconnect wire leads from power transformer,
magnetron and capacitor terminals.
3. Remove four (4) screws holding transformer to bottom
plate.
4. Remove transformer from bottom plate.
Re-install
1. Rest transformer on the bottom plate with its primary
POWER TRANSFORMER REMOVAL
terminals toward front side.
2. Secure the transformer with four (4) screws to bottom plate.
3. Re-connect wire leads (primary and high voltage) to
power transformer and filament leads of transformer to
magnetron and high voltage capacitor. Refer to
"PICTORIAL DIAGRAM".
4. Re-install outer case and check that oven is operating
properly.