SANYO EMW3000W User Manual
EM-W3000W
Microwave Oven
Service Manual
REFERENCE NO. SM-GA0005
INTRODUCTION
This Microwave Oven Service Manual is printed in a loose-leaf format. Each part is divided into sections relating
to a general group of components and each section is subdivided into various parts describing a particular
component or service procedure.
The subdividing of the subject matter plus the loose leaf form will facilitate the updating of the manual as new or
revised components and service procedures are introduced.
Each page of this service manual will be identified in the lower right hand corner and, as new or revised pages
are published, it will be easy to keep the manual up to date by following the filing instructions on the cover letter.
This Service Manual is a valuable service tool and care should be taken to keep it up to date by prompt and
proper filling of subsequent pages as they are issued.
CONTENTS
SAFETY PRECAUTIONS..........................................................................................................................................2
EM-W3000W Microwave Oven Explode Drawing .....................................................................................................3
EM-W3000W Microwave Oven Parts /Components List...........................................................................................4
1. THE HEATING PRINCIPLE OF MICROWAVE .....................................................................................................5
2. THE STRUCTURE AND WORKING PRINCIPLE OF MICROWWAVE OVEN. ....................................................6
2.1 HIGH VOLTAGE RECTIFYING CIRCUIT. ..........................................................................................6
2.2 MICROWAVE GENERATER...............................................................................................................7
2.3 COOLING SYSTEM............................................................................................................................7
2.4 ELECTRIC CONTROL SYSTEM........................................................................................................7
3. TYPICAL CIRCUIT ANALYASIS OF MICROWAVE OVEN .................................................................................10
4. HOW TO ASSEMBLE AND DISASSEMBLE MICROWAVE OVEN COMPONENTS .........................................11
4.1 THE CABINET ..................................................................................................................................11
4.2. THE DOOR COMBINATION .............................................................................................................12
4.3 THE CONTROL PANEL AND THE DOOR RELEASE MECHANISM. .............................................13
4.4 THE MAGNETRON. .........................................................................................................................13
4.5 THE TRANSFORMER......................................................................................................................14
4.6 THE FAN MOTOR. ...........................................................................................................................14
4.7 THE CAPACITOR. ............................................................................................................................15
4.8 THE DIODE. .....................................................................................................................................15
4.9 THE TURNTABLE COMBINATIOM..................................................................................................16
4.10 THE DOOR SAFTY INTERLOCKS. .................................................................................................16
THE CONTROL PANEL OF A TYPICAL MICROWAVE OVEN .......................................................................17
5. BREAKDOWN ANALYSIS AND THE MEANS OF OVERHAULING ...................................................................18
5.1 EXAMINING THE BREAKDOWN CAUSES. ....................................................................................18
5.2. SPOT EXAMINING STEPS OF THE MICROWAVE OVEN .............................................................18
5.3 REPAIRING METHOD OF SEVERAL BREAKDOWN .....................................................................21
5.4 THE CHARACTERS REQUIREMENTS OF MICROWAVE AFTER IT HAS BEEN REPAIRED ......22
6. CRITICAL PARTS SERVICING...........................................................................................................................23
6.1 IMPORTANT THINGS TO DO PRIOR TO CRITICAL PARTS SERVICING: ....................................23
6.2 Interlock Assembly Replacement and Adjustment............................................................................23
7. COMMON BREAKDOWN OF MICROWAVE OVEN AND MEANS OF REPAIRING..........................................24
SPECIFICATIONS ...................................................................................................................................................25
1
SSAAFFEETTYY PPRREECCAAUUTTIIOONNSS
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 misaligned 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.
THIS MANUAL, AS WELL AS THE INFORMATION CONTAINED IN IT, IS TO BE USED ONLY BY AN
AUTHORIZED SERVICE TECHNICIAN FAMILIAR WITH AND KNOWLEDGEABLE OF PROPER
SAFETY AND SERVICING PROCEDURES AND POSSESSING HIGH QUALITY TEST EQUIPMENT
ASSOCIATED WITH MICROWAVE AND ELECTRICAL APPLIANCE REPAIR.
ALL INDIVIDUALS WHO ATTEMPT REPAIRS BY IMPROPER MEANS OR ADJUSTMENT SUBJECT
THEMSELVES AND OTHERS TO THE RISK OF SERIOUS OR FATAL INJURY.
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PART NO. PART CODE NO NAME QTY PART NO. PART CODE NO NAME QTY
P01 GA-1000AP30P01 Oven cavity 1 P26 GA-1000AP30P26 Door latch 1
P02 GA-1000AP30P02 Touch key board 1 P27 GA-1000AP30P27 Choke cover 1
P03 GA-1000AP30P03 Door release button 1 P28 GA-1000AP30P28 Inner viewing barrier 1
P04 GA-1000AP30P04 Button spring 2 P29 GA-1000AP30P29 Shaft 1
P05 GA-1000AP30P05 Control panel 1 P30 GA-1000AP30P30 Washer 1
P06 GA-1000AP30P06 PC board holder 1 P31 GA-1000AP30P31 Mica sheet 1
P07 GA-1000AP30P07 Lower hinge 1 P32 GA-1000AP30P32 Roller ring 1
P08 GA-1000AP30P08 Foot 4 P33 GA-1000AP30P33 Ring wheel 3
P09 GA-1000AP30P09 Foot pin 4 P34 GA-1000AP30P34 Glass tray 1
P10 GA-1000AP30P10 Bottom enclosure 1 P35 GA-1000AP30P35 Upper hinge 1
P11 GA-1000AP30P11 Button lever 1 P36 GA-1000AP30P36 Outer enclosure 1
P12 GA-1000AP30P12 Microswitch mounting 1 P37 GA-1000AP30P37 Insulating film 1
bracket P38 GA-1000AP30P38 Wire harness 1 set
P13 GA-1000AP30P13 Inner rotary arm 1 P39 GA-1000AP30P39 Power cord 1
P14 GA-1000AP30P14 Outer rotary arm 1 P40 GA-1000AP30P40 Sponge 1
P15 GA-1000AP30P15 Shock proof rubber 2 B01 GA-1000AP30B01 Foam cushion 2
P16 GA-1000AP30P16 Air duct 1 B02 GA-1000AP30B02 Foam cushion 2
P17 GA-1000AP30P17 Wind baffle 1 B03 GA-1000AP30B03 Owner's manual 1
P18 GA-1000AP30P18 Bracket 1 B04 GA-1000AP30B04 Plastic bag 1
P19 GA-1000AP30P19 Fan blade 1 B05 GA-1000AP30B05 Plastic film 1
P20 GA-1000AP30P20 Fan shroud 1 B06 GA-1000AP30B06 Foam cushion 2
P21 GA-1000AP30P21 H.V.capacitor holder 1 B07 GA-1000AP30B07 Carton 1
P22 GA-1000AP30P22 Door frame 1 B08 GA-1000AP30B08 Packing belt 1
P23 GA-1000AP30P23 Door window 1 B09 GA-1000AP30B09 Wrapping nail 12
P24 GA-1000AP30P24 Door 1
P25 GA-1000AP30P25 Latch spring 1
COMPONENT NO. COMPONENT CODE NO. Name Model QTY
C01 GA-1000AP30C01 PC board GAL9823N-04B 1
C02 GA-1000AP30C02 Transformer GAL-1000U-1 1
C03 GA-1000AP30C03 Microswitch V-5230Q or VP533B-OFB 1
C04 GA-1000AP30C04 Microswitch VP331B-OD 2
C05 GA-1000AP30C05 Fuse socket FB65 1
C06 GA-1000AP30C06 Oven lamp KEI T22/125V 20W 1
C07 GA-1000AP30C07 Magnetron 2M248J-N 1
C08 GA-1000AP30C08 Thermostat KSD180 1
C09 GA-1000AP30C09 Thermostat KSD105 1
C10 GA-1000AP30C10 Turntable motor SM012 or M2CJ49Z 1
C11 GA-1000AP30C11 H.V.Capacitor CH85 1.0μF 2200V 1
C12 GA-1000AP30C12 H.V.Diode HVM12(450mA) 1
C13 GA-1000AP30C13 Fan Motor SP-6309-120 1
C14 GA-1000AP30C14 Microswitch V-5220Q or VP532B-OFB 1
C15 GA-1000AP30C15 Fuse 65TS 125V 20A 1
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11.. TTHHEE HHEEAATTIINNGG PPRRIINNCCIIPPLLEE OOFF MMIICCRROOWWAAVVEE
Microwave is one kind of radio wave whose wavelength is very short, frequency is very high. Therefore, it is
called ultrahigh frequency electromagnetic wave. Microwave can heat food mainly result in the mutual affect of
the food in the microwave field and the microwave field itself.
Under the affect of microwave field, the thermal effect mechanism produced from the mutual affect of the
microwave and the food includes two aspects. One is Dielectric loss of polar molecule; the other is conductive
loss of ion.
Usually, food is constituted of organism (plant and animal). The organism is formed by all kinds of polar water
molecule, polar protein molecule, and all sorts of saltion. The center of gravity of the positive and negative charge
in the molecule is not coinciding. In normal condition, the molecule is in irregular order due to its thermal action,
thus the food do not appear polarity. (FIG.1-la). Under the action of outer electric field, the positive end of the
polar molecule trend to the negative electric field, the negative end of polar molecule trend to the positive electric
field, and somewhat arrange in order through the direction of the electric field (FIG.1-1c). This phenomenon
usually is called “TORQUE POLARITY”. When the outer electric field apply for the opposite polarity, the polar
molecule then arrange an opposite direction order accordingly (FIG.1-1b). If the direction of the outer electric field
changed repeatedly, the polar molecule would repeatedly sway accordingly. During the swaying, it is
understanding that the polar molecule would produce heat due to somewhat similar friction among them. When
the electric field is applied for ultrahigh frequent microwave field from the outside, its direction would change tens
billion times per second, so do the molecule. This kind of molecule swaying producing similar frictional heat from
the interference and block of the action strength among the molecule, and changed to microscopic microwave
heating. Microwave heating not only concerned the nature of the matter itself, but also closely connected with the
electric strength and frequency. When the frequency is low, the molecule swaying rate and the acute degree of
the mutual friction among the molecule is low, and would produce much heat. When the frequency is too high, as
the swing of the polar molecule is with rotating inertia, it made the swing do not in line with the changing rhythm
of the electric field because of the friction drag, thus, actually lowed the polar molecule swaying speed. The
friction dragging degree is concerning about the magnelectric wave frequency, polar molecule shape, and the
matter’s sticky degree. To different matter’s molecule, there is different special frequency zone. Those absorbing
microwave energy from this zone are most capable to turn microwave energy to heat energy.
(a) (b) (c)
Fig.1-1
Apart from the above said action, there is another action which is electric ion under the action of microwave field,
act fiercely accompanied with the acceleration of electric field. The positive ion transfer to the negative polarity of
the field while the negative ion does opposite. Accompanying with the changing electric field, the electric ion
hanging accordingly. During the transferring, heat produced with the crash among the ion. This kind of action
takes the main effect to those microwaves heating of high salt molecule.
No matter it is the polar molecule swaying or the ion transferring, they both are turning the microwave energy
which the heating matter got from the microwave field to heat energy. From the analysis of theory, we can draw
such a conclusion that the power which a unit of volume matter absorbed from the microwave field as the
following formula:
Pa=KE fErtgδ
Pa Stands for the power the heated matter adsorbed from the microwave field.
5
K Stands for a constant
E Stands for the microwave frequency.
f Stands for the microwave frequency.
tgδ Stands for loss angle tangent of the heated matter.
Er Stands for relative dielectric constant of the heated matter.
22.. TTHHEE SSTTRRUUCCTTUURREE AANNDD WWOORRKKIINNGG PPRRIINNCCIIPPLLEE OOFF MMIICCRROOWWWWAAVVEE OOVVEENN..
Microwave oven can be classified to many kinds
according to various construction, volume and control
function. But anyhow, the main electric parts are all
composed of high voltage rectification, cooling system.
Microwave generator, electric control system and
heating chamber (FIG.2-1). Its working process are as
follows: 120V power frequency voltage transferred to
the rectifier through electric control system, and then be
changed to 4000V direct volt-age by the rectifier, and be
then transferred to the microwave generator, the
generator stars working to transfer the microwave
energy to the heating chamber for heating food through
wave guide tube. At the same time, the electric control
system set off the cooling system to cool the working
rectifier and the microwave generator to keep the oven
working steadily from a too high temperature. If
something wrong with the cooling system cause the temperature too high, the control system would cut off the
power automatically to prevent microwave generator being damaged form the high temperature. Now, we’d like to
introduce the working principle of each part of the widely used model, mechanical control and touch control
microwave oven.
22..11 HHIIGGHH VVOOLLTTAAGGEE RREECCTTIIFFYYIINNGG CCIIRRCCUUIITT..
At present, home use microwave oven adopt this high voltage rectifying circuit as shown at diagram 2-2.The
circuit is a single phase, semi-wave, double voltage rectifying circuit. The circuit has only a high voltage capacitor,
a high voltage diode, a magnetic leakage transformer besides the magnetron, is very simple.
The working principle of the circuit: 120V power boosted through the transformer, output about 2000V alternating
high voltage current when the high voltage winding is at the positive half-circle, the high voltage winding is at the
negative half-circle, the diode is cut off and the magnetron is conducted. The electricity charged at the positive
half-circle of the capacitor is series connected with the positive phase of the winding voltage, and got a doubled,
about 4000V direct high voltage, then transferred to between the cathode and the anode of the magnetron.
120V
120V
120V
Fig.2-2
6
Fig.2-3
22..22 MMIICCRROOWWAAVVEE GGEENNEERRAATTEERR..
Microwave generator is the heart of microwave oven. The quality of a microwave oven mostly depends on the
quality of the microwave generator. A microwave generator is mainly composed of magnetron and its power
supply circuit, FIG.2-3 is the typical circuit diagram of the present used microwave oven’s generator. The power
supply circuit is composed of rectifying circuit and filament circuit.
Usually, we adopt continuous wave magnetron. It can turn the direct energy which is applied to the magnetron
after being high voltage rectified to microwave energy, the power supply circuit supply a direct high voltage
between the cathode and anode of the magnetron, a filament voltage to the cathode filament of the magnetron.
The working process of the magnetron: When the anode volt-age gradually rises from zero, the anode current is
approx.zero, the power is very small as well. When the anode voltage rises to “THRESHOLD” voltage value, the
magnetron starts oscillating, and the anode current would increase obviously, provided the anode voltage rises a
little more, the anode current would increase a lot (FIG.2-4), and would reach the rate value quickly.
If the anode voltage is undulating, it would cause the anode
current swing fiercely, even made the magnetron stop oscillating.
For keeping a steady output, the power supply circuit of the
oven must supply a stead direct current voltage. The filament
voltage of the magnetron must be supplied by an alternating
current voltage. For simplifying the circuit, it would be supplied
by the same leakage magnetic transformer with the anode
power (high voltage power). The filament of the magnetron
which the present used microwave ovens are all treated through
some special technology, and all have the cold start character.
)
V
k
(
m
b
e
e
g
a
t
l
o
v
e
d
o
n
a
But when in cold start, there still is a very strong surge electric
field attached to the surface of the anode, and would be harmful
to the anode. In order to reduce the surge voltage, the filament
of the magnetron must be connected as the FIG.2-3 shown. In
this figure, when the anode current of the magnetron circulates,
anode current
Ib(mA)
the filament current should flow to the FA end from the lower
end.
Fig.2-4
22..33 CCOOOOLLIINNGG SSYYSSTTEEMM
In the working process of the microwave oven, the magnetron often makes the anode temperature rise due to
anode loss
caused by the electronics strike the oven surface and the heat radiate of the cathode. To prevent the anode
temperature rise too high, thus affect the working steady and its life span, it is necessary to cool the magnetron.
According to the different models and rate output of the magnetron, compelling wind cooling and flowing
water-cooling can be adopted. Usually, the home used microwave oven adopts the compelling wind cooling
method, and all are fixed with cooling fin.
Cooling system includes fan motor, air duct, air entrance, air vent etc. The flowing direction of the cooling wind
should. Be parallel to the cooling fin of the magnetron. Generally, we adopt the method of air blast rather than air
absorb. And all the cabinet of the oven is with air entrance and air vent, the hot wind blowing through the
magnetron is guided with air tube to improve the cooling effect. In the technical parameter chart of the magnetron,
it usually will give out the requirement of cooling wind. A shortage of cooling wind would damage the character of
the magnetron, even burn out the magnetron. The amount that the fan blasted should not be less than the
requirement. When fix the fan, attention must be paid to prevent the cool wind from blowing directly to the glass
part of the magnetron to avoid blasting.
22..44 EELLEECCTTRRIICC CCOONNTTRROOLL SSYYSSTTEEMM..
To those mechanical control microwave oven, electric control system mainly composes of interlock switch, timer,
power distributor and thermal cutout, etc. The electric control system of those tough control microwave oven is
mainly composed of interlock switch, computer controller and thermal cutout, etc.
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22..44..11 DDOOOORR IINNTTEERRLLOOCCKK SSWWIITTCCHH
Drawing 2-5(a) is the circuit and construction diagram
of the door interlock switch of a microwave oven. It
mainly consists of interlock switches (S1, S2), and
monitor switch (S3), door hook and starting mechanism
of the door interlock switch.
There fixed hooks on the oven door, and opened two
rectangle hole at the corresponding place at the right of
the oven and the hook. Inside each rectangle hole,
L
E
N
there fixed a micro switch. When the oven door closed,
the two hook on it would insert into the rectangle hole,
and just push down several micro switches. At that time,
S1, S2 are closed, S3 is cut off, and the microwave
oven is under preparation of working.
door closed
To that mechanical control microwave oven, no sooner
you turn the time switch to set the heating time than the
power would be supplied to the back to start the oven. To those touch
control microwave oven, hardly do you set the heating time and power,
and touch the start button when the power would supplied to the back to
start the oven.
When pressing down the door release button or pulling the door handle
to open the door, the safety interlock switches S1, S2 are cut off, and
the monitor switch S3 is closed, and the microwave oven would stop
operating immediately. Provided due to some man - made or the
appliance itself reasons, when the door is open, and the safety interlock
switches S1, S2 are not automatically cut off, due to the existence of the
fuse
ch holder
tch
itch
main latch switch
pilot switch
(a)
Fig.2-5
door hook
S
1
3
S
2
S
assistant latch switch
latch switch holder
latch switch
pilot switch
monitor switch (S3) which is still at conducted condition, the monitor
switch would immediately make the 120V voltage short-circuited and
screw
blow up the fuse, and will never let the microwave oven working when
the door is open.
From this we can understand the function of the interlock switch is
when the door is unclosed, the oven wouldn’t work, when the door is
opened when the oven is working, it would stop the working
door hook
latch switch
pilot switch
immediately (FIG.2-5b).
22..44..22 TTIIMMEE AANNDD PPOOWWEERR DDIISSTTRRIIBBUUTTOORR
door release button
Fig.2-5（b）
screw
Time and power distributor is mainly composed of timer motor and two
sets of gear switch S4 and S5. When the timer is at zero position, the gear switches are cut off, when the heating
time is settled, the gear switch is closed. When started
the oven, the time motor starts working. When it
reaches the settled time, it would cut off the gear
switch (s4) to step the oven working. The gear switch
timer & power motor
transformer
(S5) is designed for controlling the output of the
microwave oven, actually for controlling the output of
the magnetron. It mainly by the method which make
120V
the magnetron working internally at the same working
point to change the output of the magnetron. This
4
S
5
S
method was called “CONDUCTION RATIO CONTROL”.
But there is another method which is called
Fig.2-6
“ELECTRIC LEVEL CONTROL” which is through
changing the working point (such as anode voltage or magnetic field) to change the output of the magnetron.
Because of conduction ratio control method is low cost, high function and high reliability, it is widely used for
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