Sanyo EMZ2000S, EMZ2000SSM-GA0004 Schematic

Microwave Oven

EM-Z2000S

Service Manual

REFERENCE NO. SM-GA0004

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-Z2000S Microwave Oven Explode Drawing .......................................................................................................3

EM-Z2000S Microwave Oven Parts & Components List...........................................................................................4

THE HEATING PRINCIPLE OF MICROWAVE .........................................................................................................5

THE STRUCTURE AND WORKING PRINCIPLE OF MICROWWAVE OVEN.........................................................6

1.1 HIGH VOLTAGE RECTIFYING CIRCUIT. ..........................................................................................6

1.2 MICROWAVE GENERATER...............................................................................................................7

1.3 COOLING SYSTEM............................................................................................................................7

1.4 ELECTRIC CONTROL SYSTEM........................................................................................................7

TYPICAL CIRCUIT ANALYASIS OF MICROWAVE OVEN .....................................................................................10

HOW TO ASSEMBLE AND DISASSEMBLE MICROWAVE OVEN COMPONENTS .............................................11

1.5 THE CABINET ..................................................................................................................................11

THE DOOR COMBINATION ............................................................................................................................12

1.7 THE CONTROL PANEL AND THE DOOR RELEASE MECHANISM. .............................................13

1.8 THE MAGNETRON. .........................................................................................................................13

1.9 THE TRANSFORMER. .....................................................................................................................14

1.10 THE FAN MOTOR. ...........................................................................................................................14

1.11 THE CAPACITOR. ............................................................................................................................15

1.12 THE DIODE. .....................................................................................................................................15

1.13 THE TURNTABLE COMBINATIOM..................................................................................................16

1.14 THE DOOR SAFTY INTERLOCKS. .................................................................................................16

THE CONTROL PANEL OF A TYPICAL MICROWAVE OVEN .......................................................................17

BREAKDOWN ANALYSIS AND THE MEANS OF OVERHAULING .......................................................................18

1.16 EXAMINING THE BREAKDOWN CAUSES. ....................................................................................18

SPOT EXAMINING STEPS OF THE MICROWAVE OVEN.............................................................................18

1.18 REPAIRING METHOD OF SEVERAL BREAKDOWN .....................................................................21

1.19 THE CHARACTERS REQUIREMENTS OF MICROWAVE AFTER IT HAS BEEN REPAIRED ......22

CRITICAL PARTS SERVICING ...............................................................................................................................23

1.20 IMPORTANT THINGS TO DO PRIOR TO CRITICAL PARTS SERVICING:....................................23

1.21 Interlock Assembly Replacement and Adjustment............................................................................23

COMMON BREAKDOWN OF MICROWAVE OVEN AND MEANS OF REPAIRING..............................................24

SPECIFICATIONS ...................................................................................................................................................25

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.

EM-Z2000S Microwave Oven Explode View

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COMPONENT No.

COMPONENT CODE Name Model QTY

C01 GA-1000AS23C01 Fuse 65TS 125V 20A 1

C02 GA-1000AS23C02 Fan motor SP-6309-120 1

C03 GA-1000AS23C03 H.V.Capacitor CH85 1.0µF 2200V 1

C04 GA-1000AS23C04 H.V.Diode HVM12(450mA) 1

C05 GA-1000AS23C05 PC board GAL9823 1

C06 GA-1000AS23C06 Turntable motor SM012 or GAL-5-120-TD 1

C07 GA-1000AS23C07 Transformer GAL-1000U-1 1

C08 GA-1000AS23C08 Magnetron 2M248K-N 1

C09 GA-1000AS23C09 Microswitch V-5230Qor VP533B-OFB 2

C10 GA-1000AS23C10 Microswitch V-5220Qor VP532B-OFB 1

C11 GA-1000AS23C11 Thermostat KSD180 1

C12 GA-1000AS23C12 Thermostat KSD105 1

C13 GA-1000AS23C13 Oven lamp KEI T22/120V 20W 1

EEMM--ZZ22000000SS MMiiccrroowwaavvee OOvveenn PPaarrttss LLiisstt

PART PART CODE NO NAME QTY PART PART CODE NO NAME QTY

P01 GA-1000AS23P01 Oven cavity 1 P32 GA-1000AS23P32 Air duct 1

P02 GA-1000AS23P02 Door frame 1 P34 GA-1000AS23P34 Wire fastener 2

P03 GA-1000AS23P03 Outer enclosure 1 P36 GA-1000AS23P36 Upper hinge 1

P04 GA-1000AS23P04 Stainless steel door 1 P37 GA-1000AS23P37 Sponge 1

P38 GA-1000AS23P38 Spacer 1

P05 GA-1000AS23P05 Door window 1 P39 GA-1000AS23P39 Washer 1

P06 GA-1000AS23P06 Door 1 P40 GA-1000AS23P40 Shaft 1

P07 GA-1000AS23P07 Choke cover 1 P41 GA-1000AS23P41 Roller ring 1

P08 GA-1000AS23P08 Inner viewing barrier 1 P42 GA-1000AS23P42 Ring wheel 3

P09 GA-1000AS23P09 Mica sheet 1 P43 GA-1000AS23P43 Glass tray 1

P10 GA-1000AS23P10 Fan shroud 1 P44 GA-1000AS23P44 Lamp holder 1

P11 GA-1000AS23P11 Fan blade 1 P45 GA-1000AS23P45 Door handle 1

P12 GA-1000AS23P12 Capacitor holder 1 P46 GA-1000AS23P46 Wire fastener 1

P13 GA-1000AS23P13 Control panel 1 P47 GA-1000AS23P47 Wire harness 1 set

P14 GA-1000AS23P14 Control panel enclosure 1 P48 GA-1000AS23P48 Power cord 1

P15 GA-1000AS23P15 Sponge 1 P51 GA-1000AS23P51 Touch key board 1

P16 GA-1000AS23P16 Nameplate 1 P52 GA-1000AS23P52 Sponge 1

P18 GA-1000AS23P18 Bottom enclosure 1 B01 GA-1000AS23B01 Foam cushion 2

P19 GA-1000AS23P19 Latch spring 1 B02 GA-1000AS23B02 Foam cushion 2

P20 GA-1000AS23P20 Door latch 1 B03 GA-1000AS23B03 Plastic bag 1

P21 GA-1000AS23P21 Foot 4 B04 GA-1000AS23B04 Owner's manual 1

P22 GA-1000AS23P22 Foot pin 4 B05 GA-1000AS23B05 Foam cushion 1

P23 GA-1000AS23P23 Transformer bracket 1 B06 GA-1000AS23B06 Plastic film 1

P24 GA-1000AS23P24 Insulating film 1 B07 GA-1000AS23B07 Foam cushion 2

P25 GA-1000AS23P25 Shock proof rubber 2 B08 GA-1000AS23B08 Packing belt 1

P26 GA-1000AS23P26 Nameplate 1 B09 GA-1000AS23B09 Carton 1

P27 GA-1000AS23P27 Microswitch mounting 1 B10 GA-1000AS23B10 Wrapping nail 12

Bracket PART PART CODE NO NAME QTY

P28 GA-1000AS23P28 Inner rotary arm 1 P32 GA-1000AS23P32 Air duct 1

P29 GA-1000AS23P29 Outer rotary arm 1 P34 GA-1000AS23P34 Wire fastener 2

P31 GA-1000AS23P31 Power cord holder 1 P36 GA-1000AS23P36 Upper hinge 1

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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.

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.

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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.

11..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

Fig.2-2

Fig.2-3

11..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 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

11..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.

11..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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