Midea EMCX2908 Schematic

54321

103

CON1

温度传感器

EC1 47U/16V

2.7V/DO35

P0.3

R43

R62

P0.5 P1.0

3 2 1

IC1

Vss4SDA A2 A1

24C02

R15

R16

4.7k(%)

4.7k

R14

123

100k

TR7 8550

+5V

R46

R44

20K

P4.1

RN2

P1.1/BUZ

P1.2 P1.3 P1.4

P1.5 P1.6 P1.7

P4.0

SWD

R592KR60

2 3 4

5 6 7

SWC

IC3 IC/ULN2003

IN1 IN2

IN3 IN4 IN5 IN6

IN7

TR8 8550

R38

RESET

R37 10K

C14

C13

104

RN10K*7

P0.4

P4.5

P4.4

R47

R45

R49

VSS8VDD

+5V

R63

10K

TR8

R60

10K

8050

C24

104

Title

R61

3K3

Number RevisionSize

Date: 26-Mar-2008 Sheet of File: C:\PROG RAM FILES\DESIGN EXPLORER 99 SE\EXAMPLES\

SCL

Vcc

P4.2

SWB

OUT1 OUT2

OUT3 OUT4 OUT5 OUT6

OUT7

C17

104

R48 20K

R61 2K

1N4007

D11

+5V

6 7

+5V C2

R50 20K

P4.3

SWA

R62

15 14 13

12 11 10 9

R17 10K

104/25V

+12

R18 10K

P0.1

P0.0

+12

R58

BUZ1

RLY1

+12

LAMP

RLY2

+12

FAN

RLY3

CONVECTION

DOOR1

RLY4

GRILL

RLY5

MICRO

+12

Drawn By:

微波炉电脑板ACXEEMP-02

+5V

P2.0

TR1

8550

TR2

8550

4.7K

TR3

8550

4.7K

TR4

8550

4.7K

TR5

8550

4.7K

TR6

8550

4.7K

P2.1

P2.2

P2.3

+5V

P2.4

P2.5

P2.6

P3.2 P3.1 P3.0 P4.6 P4.5 P4.4 P4.3 P2.7 P2.6 P2.5

44 43 42 41 40 39 38 37 36 35 34

471C4471C5471C6471

EC2 47U/16V

+5V

s17/txd/p3.2 s16/rxd/p3.1 s15/p3.0 s14/p4.6 s13/p4.5 s12/p4.4 s11/p4.3 s10/p2.7 s9/p2.6 s8/p2.5 s7/p2.4

104/50V

P3.3

P3.4

P3.5

s18/int0/p3.3

tout/int1/p3.4

S3F9488-QFP

C10

471

C9 20P

CSA1 4MHz

P3.6

Vss

Vdd

tack/int2/p3.5

tacap/int3/p3.6

44-QFP

R34

Xin

Xouot

C20 104

P2.3

P2.2

P2.1

P2.0

P4.2

P4.1

P4.0

P1.7

+5V

R55

R54

10K

10K R52 1K

P0.6 P0.7

C22

C21

R53 1K

471

P3.0

P3.6

EC4

R41

R42 390/1/4W

P3.1

C16 471

Q1 8050/TO92

220UF/16V

P3.4

P3.5

DIG1 DIG2 DIG3 DIG4

P3.3

34512678

+5V

CON-WRITE1

6PIN

CON2

3.96MM*7

6 5 4 3 2 1

7 6 5 4 3 2 1

RN1 RN20K*7

FAN LAMP N L

P3.6 P3.5

test resetb

TRAN1

+5V

4148

R26

220

R39

D2 1N4007

220

1N4007

R29

R28

R27

R30

220

C15 103

D5 1N4007

470UF/25V

P3.2

LED1

11 13

R31

R32

R33

220

P2.7 P2.4 P2.5 P2.6 P2.3 P2.2 P2.1 P2.0

R40

4.7V 2K

EC3

C18 104

5.6V/DO35

1N4007

PT6329A

1N4007

470UF/25V

+12

EC5

C19

R51

104

5K1(1/4W)

R7 2K

R10 2K

R11 2K

R12

R13

C11

471

P0.0

P0.1

TEST

test

XTin/p0.0

XTout/p0.1

p0.2/resetb

p0.3/adc8

p0.4/com7/adc7

p0.5/com6/adc6 p0.6/com5/adc5 p0.7/com4/adc4

p1.0/adc3/tbpwm

p1.1/adc2/buz

p1.2/adc1 p1.3/adc0

p1.4/com323p1.5/com224p1.6/com125p1.7/com026p4.0/s027p4.1/s128p4.2/s229p2.0/s330p2.1/s431p2.2/s532p2.3/s6

P1.6

P1.5

P1.4

B1 SW_CONDER

C12 20P

AVref

SW1

SW2

SW3

SW4

SW5

SW6

SW7

+5V

R35 1K

R36

1.2k

IC2

RESET

P0.3 P0.4

14 15

P0.5

P0.6

P0.7

18 19

P1.0

P1.1/BUZ

P1.2

P1.3P2.4

P4.6

C23

104

1 2 3 4 56

MICROWAVE OVEN

MODEL:

AC930AMP-S00C

(900W 220 V 50Hz)

SERVICE MANUAL

CAUTION

BEFORE SERVICING THE UNIT，READTHE SAFETY PRECAUTIONS IN THIS MANUAL

SAFETY PRECAUTIONS

This device is to be serviced only by properly qualified service personnel. Consult the service manual for proper service procedures to assure continued safety operation and for precautions to be taken to avoid possible exposure to excessive microwave energy.

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) pr oper 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 a lignment, integrity, and connections. D) Any defective or misadjusted components in the interlock, monitor, door seal, and microwave generatio n 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 should be performed on each oven prior to release to the owner.

CAUTION

MICROWAVE RADIATION

DO NOT BECOME EXPOSED TO RADIATION FROM THE MICROWAVE GENERATOR OR OTHER PARTS CONDUCTING MICROWAVE ENERGY.

TABLE OF CONTENTS

（page）

SAFETY PRECAUTIONS---------------------------------------------------------Inside front cover

CAUTIONS------------------------------------------------------------------------------------------------1-1

THE HEATING PRINCIPLE OF MICROWAVE--------------------------------------------------2-1

INSTALLATIONS----------------------------------------------------------------------------------------3-1

OPERATING INSTRUCTIONS----------------------------------------------------------------------4-1

SCHEMATIC DIAGRAM--------------------------------------------------------------------------4-1 CIRCUIT DESCRIPTION-------------------------------------------------------------------------4-2

SERVICE INFORMATION-----------------------------------------------------------------------------5-1

TOOLS AND MEASURING INSTRUMENTS------------------------------------------------5-1 MICROWAVE LEAKAGE TEST----------------------------------------------------------------5-2 MEASUREMENT OF MICROWAVE POWER OUTPUT---------------------------------5-3 TROUBLE SHOOTING PROCEDURES------------------------------------------------------5-4 COMMON BREAKDOWN AND MEANS OF REPAIRING-------------------------------5-8 I M PORTANT TH I N GS TO DO PRIOR T O C RITICAL PA R T S E RVIC I N G-------------------------5-9 SAFETY CHECKS AND TESTS AFTER SERVING--------------------------------------5-10

EXPLODED VIEW---------------------------------------------------------------------------------------6-1 REPLACEMENT PARTS LIST-----------------------------------------------------------------------6-1

CAUTIONS

Unlike other appliances, the microwave oven is high-voltage and high-current equipment. Though it is free from danger in ordinary use, extreme care should be taken during repair.

• DO NOT operate on a 2-wire extension cord during repair and use.

• NEVER TOUCH any oven components or wiring during operation.

• BEFORE TOUCHING any parts of the oven, always remove the power plug from the outlet.

• For about 30 seconds after the oven stops, an electric charge remains in the high voltage capacitor. When replacing or checking, you must discharge the high voltage capacitor by shorting across the two terminals with an insulated screwdriver.

• Remove your watches whenever working close to or

replacing the Magnetron.

• DO NOT touch any parts of the control panel circuit. A resulting static electric discharge may damage this P.C.B.

• NEVER operate the oven with no load.

• NEVER injure the door seal and front plate of the oven cavity.

• NEVER put iron tools on the magnetron.

• NEVER put anything into the latch hole and the interlock switches area.`

1-1

MICROWAVE RADIATION

Personnel should not be exposed to the microwave energy which may radiate from the magnetron or other microwave generating device if it is improperly used or connection. All input and output microwave connections, waveguide, flange and gasket must be secure never operate the device without a microwave energy absorbing load attached. Never look into an open waveguide or antenna while the device is energized.

• Proper operation of the microwave oven requires that the magnetron be assembled to the waveguide and cavity. Never operate the magnetron unless it is properly installed.

• Be sure that the magnetron gasket is

properly

installed around the dome of the tube

whenever

installing the magnetron.

THE OVEN IS TO BE SERVICED ONLY BY PROPERLY QUALIFIED SERVICE PERSONNEL.

THE HEATING PRINCIPLE OF MICROWAVE

Microwave is one kind of radio wave whose wave length is very short, frequency is very high. Therefore, it is called ultrahigh frequency electromagnetic wave. Microwave can heat food mainl y result in the mutual affect of the food in the microwave field and 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 constitute of organism (plant and animal).The organism is formed by all kinds of polar water molecule, polar protein molecule, and all sorts of salt ion. The center of gravity of the positive and negative charge in the molecule is not c oincide. In normal condition, the molecule is in irregular order due to its thermal action, thus the food do not appear polarity (FIG.11a).Under the action of outer electric field, the positive end of the polar molecule tre nd 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 be 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 understands 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 chang e 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 field 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 a bout the ma gneto electric wave frequenc y, polar molecule shape, and the matter’s sticky degree. To different matter’s molecule, there are different special frequency zone. Those ado absorb microwave energy from these zone are most capable to turn microwave energy to heat energy. Apart from the above said action, there is another action which is electric ion under t he 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 do opposite. Accompanying with the changing electric field, the electric ion changing according ly. During the transferring, heat produced with the crash among the ion. This kind of action take the main effect to those microwave 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 heatin g matter got from the microwave field to hear 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=K·E· F·Er·tgδ Pa Stands for the power the heated matter absorbed from the microwave field.

K Stands for a constant E Stand for microwave field strength F Stands for the microwave frequency. Er Stands for relative dielectric constant of the heated matter. tgδStands for loss angle tangent of the heated matter

2-1

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