Bosch Hmv8050 Service Manual

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MICROWAVE OVEN

SERVICE MANUAL

MODEL: HMV8050

CAUTION

BEFORE SERVICING THE UNIT, READ THE SAFETY PRECAUTIONS IN THIS MANUAL.

CAUTION

WARNING TO SERVICE TECHNICIANS

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 misadjusted 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.

• Proper operation of the microwave ovens requires that the magnetron be assembled to the wave guide 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.

• Routine service safety procedures should be exercised at all times.

• Untrained personnel should not attempt service without a thorough review of the test procedures and safety
information contained in this manual.

FOREWORD

Read this Manual carefully. Failure to adhere to or observe the information in this Manual may result in exposing
yourself to the Microwave Energy normally contained within the oven cavity.

TABLE OF CONTENTS

(Page)

SAFETY PRECAUTIONS ................................................................................................................Inside front page

SPECIFICATIONS................................................................................................................................................ 1-1

CAUTIONS ........................................................................................................................................................... 2-1

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

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

CONTROL PANEL ............................................................................................................................................... 4-1

CONTROL PANEL INSTRUCTIONS.................................................................................................................... 4-2

OVERALL CIRCUIT DIAGRAM............................................................................................................................ 5-1

SCHEMATIC DIAGRAM....................................................................................................................................... 5-1

MATRIX CIRCUIT FOR TOUCH KEY BOARD .................................................................................................... 5-2

GENERAL INFORMATION FOR SERVICE ......................................................................................................... 6-1

GENERAL PRECAUTIONS IN USE .................................................................................................................... 6-1

TRIAL OPERATION ............................................................................................................................................. 6-1

FEATURES AND SPECIFICATIONS FEATURES............................................................................................... 6-1

SERVICE INFORMATION.................................................................................................................................... 7-1

PRECAUTIONS AND REPAIR SERVICE TIPS ................................................................................................... 7-1

MICROWAVE LEAKAGE TEST ........................................................................................................................... 7-2

POWER OUTPUT MEASUREMENT.................................................................................................................... 7-3

DISASSEMBLY INSTRUCTIONS ........................................................................................................................ 7-4

INTERLOCK SYSTEM ....................................................................................................................................... 7-12

INTERLOCK CONTINUITY TEST ...................................................................................................................... 7-14

TEST AND CHECKOUT PROCEDURES AND TROUBLESHOOTING............................................................. 7-15

A. TEST PROCEDURES.................................................................................................................................... 7-15

B. CHECKOUT PROCEDURES......................................................................................................................... 7-20

C. TROUBLESHOOTING ................................................................................................................................... 7-23

EXPLODED VIEW ................................................................................................................................................ 8-1

REPLACEMENT PARTS LIST ............................................................................................................................. 9-1

SPECIFICATIONS

Rated Power Consumption ................................Microwave 1500 W

Convection 1500 W

Microwave Output ...............................................Microwave 850 W (IEC60705)

Convection 1350 W

Frequency ..........................................................2450 MHz ± 50 MHz

Power Supply .....................................................120 V~ 60 Hz

Rated Current ....................................................Microwave 13.0 A

Convection 13.0 A

Magnetron Cooling .............................................Forced Air Cooling

Rectification .......................................................Rectification Voltage Double Half-Wave

Door Sealing ......................................................Choke System

Safety Devices ...................................................Magnetron Thermostat: Open at 150 °C ± 5 °C

Close at 0 °C ± 5 °C

............................................................................Oven Thermostat: Open at 145 °C ± 5 °C

Close at 0 °C ± 5 °C

............................................................................Fuse(20A)

............................................................................Primary Interlock Switch

............................................................................Secondary Interlock Switch

............................................................................Interlock Monitor Switch

Magnetron ..........................................................2M246

Cook top Lamp ...................................................130 V, 35 W

Cavity Lamp .......................................................130 V, 35 W

Timer ..................................................................Digital, up to 99 min. 99 sec. (in each cooking stage)

Tray ....................................................................Tempered Safety Glass

Overall Dimensions ............................................2915/16”(W)x167/16”(H)x153/8”(D)

Oven Cavity Size ...............................................211/4”(W)x97/16”(H)x143/16”(D)

Effective Capacity of Oven Cavity ......................1.7 Cu.ft.

Accessories ........................................................Use & Care Guide, Cooking Guide, Installation Manual

Exhaust Adapter, Exhaust Damper, Mounting Kit & Two Filter
Shaft, Rotating Ring, Glass Tray, Grill Rack, Metal Tray

SWITCH CHART

PRIMARY

SWITCH MODE

CONDITIONS

DOOR OPEN
DOOR CLOSED

NOTE: Use the above switch chart with circuit diagram on page 5-1.

INTERLOCK

SWITCH

COM

NO

OPEN OPEN CLOSE

CLOSE CLOSE OPEN

1-1

SECONDARY

INTERLOCK

SWITCH

COM

NO

INTERLOCK

MONITOR

SWITCH

COM

NC

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.

• 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.

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.

ANTENNA

COOLING FIN

MAGNETRON
CHASSIS GROUND

Gasket

FILAMENT
TERMINALS

MAGNETRON

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

2-1

INSTALLATIONS

Plug with Ground
Prong

Properly Polarized
and Grounded
Outlet

BEFORE YOU BEGIN, READ THE FOLLOWING INSTRUCTIONS COMPLETELY AND CAREFULLY.

PRECAUTIONS ON INSTALLATION

A. Plug the power supply cord into a 120V AC, 60Hz,

single-phase power source with a capacity of at
least 20 amperes.

B. Avoid placing the unit in a location where there is

direct heat or splashing water.
C. Install the unit on the mounting plate firmly.
D. Place the unit as far away as possible from TV,

radio, etc. to prevent interference.

GROUNDING INSTRUCTIONS

For personal safety, this appliance must be fully
grounded at all times.

In the event of an electrical short circuit, grounding
reduces the risk of electrical shock.
The plug must be plugged into an outlet that is
properly installed and grounded.

CAUTION

This unit is equipped with a 3-prong plug for your
safety. If the wall outlet is a grounded 3-hole type,
the unit will be grounded automatically.

WARNING

Improper use of the grounding plug can result in a
risk of electric shock.
Do not, under any circumstances, cut or remove the
third ground prong from the power cord plug.

3-1

CONTROL PANEL

OPERATING INSTRUCTIONS

1

3

2

5

6

8

11

12

14

15

17

18

20

21
23
24

4

7

10

9

13

16

19

22

25

26

27

28

4-1

CONTROL PANEL INSTRUCTIONS

1. DISPLAY: The Display includes a clock and indicators

to tell you time of day, cooking time settings, and
cooking functions selected.

2. MICRO.: Touch this pad when setting Microwave

cooking.

3. CONV.: Touch this pad when setting Convection

cooking.

4. COMBI.: Touch this pad when setting combination

cooking or preheat.

5. SENSOR POPCORN: Touch this pad when popping

popcorn in your microwave oven. The oven’s sensor
will tell the oven how long to cook depending on the
amount of humidity it detects from the popcorn.

6. SENSOR COOK: Touch this pad to cook baked

potato, frozen vegetable, fresh vegetable, canned
vegetable, frozen entrée, and rice. The oven’s sensor
will tell the oven how long to cook depending on the
amount of humidity coming from the food.

7. SENSOR REHEAT: Touch this pad to reheat

casserole, dinner plate, pizza slice, and soup/sauce.
The oven’s sensor will tell the oven how long to cook
depending on the amount of humidity coming from the
food.

8. SPEED AUTO COMBI: Touch this pad when setting

weight combination cooking.

9. AUTO COOK: Touch this pad to cook Bacon, Fresh

Roll & Muffin, Frozen Roll & Muffin, Beverage, Chicken
Pieces, and Hot Cereal.

10. AUTO DEFROST: Touch this pad to select food type

and defrost food by weight.

11. CUSTOM COOK: Touch this pad to recall one

cooking instruction previously programmed into
memory.

12. ADD 30 SEC.: Touch this pad to set, start quickly and

microwave cooking at 100% power level.

13. CUSTOM SET: Touch this pad to change the oven’s

default settings for sound, clock, display speed, and
defrost weight.

14. NUMBER: Touch number pads to enter cooking time,

power level, quantities, weights, or cooking
temperature.

15. TURNTABLE ON/OFF: Touch this pad to turn off the

turntable. OFF will appear in the display.
NOTE: This option is not available in sensor cook and
defrost modes.

16. POWER: Touch this pad to select a cooking power

level.

17. More: Touch this pad to add ten seconds of cooking

time each time you press it.

18. STOP/CLEAR: Touch this pad to stop the oven or to

clear all entries.

19. START/ENTER: Touch this pad to start a function or

enter all entries. If you open the door after oven
begins to cook, touch START/ENTER again.

20. Less: Touch this pad to subtract ten seconds of

cooking time each time you press it.

21. SOFTEN: Touch this pad to soften Butter, Ice Cream,

Cream Cheese, or Frozen Juice.

22. MELT: Touch this pad to melt Butter or Margarine,

Chocolate, Cheese, or Marshmallow.

23. CLOCK: Touch this pad to enter the time of day.

24. LIGHT ON/OFF: Touch this pad to turn the cooktop/

countertop light on or off.

25. KITCHEN TIMER: Touch this pad to set the timer.

26. VENT ON/OFF: Touch this pad to turn the fan on/off.

27. VENT 5-SPEED: Touch this pad to choose one of 5

fan speeds.

28. VENT AUTO TIME SET: Touch this pad when setting

ventilation time. (1, 3, 5, 10, and 30 minutes.)

4-2

OVERALL CIRCUIT DIAGRAM

SCHEMATIC DIAGRAM

5-1

MATRIX CIRCUIT FOR TOUCH KEY BOARD

4

MICRO.

DEFROST

AUTO

N.C

TIMER

KITCHEN

START

ENTER/

POPCORN

POWER

N.C

COOK

AUTO

COOK

CLEAR

STOP/

REHEAT

TURNTABLE

ON/OFF

ON/OFF 5-SPEED

SENSOR

SENSOR

N.C N.C

SENSOR

ON/OFF

LIGHT

1

2

3

N.C

AUTO

8

30 SEC.

CLOCK

9

0

MORE

COMBI

LESS

SOFTEN

SPEED

TIME SET

ADD

AUTO

CONV.

MELT

N.C

COMBI.

5

6

7

(VENT) (VENT)

(VENT)

CUSTOM

SET

CUSTOM

COOK

13

12

11

10

9

8

1

2

3

4

5

6

7

KEY MATRIX

5-2

GENERAL INFORMATION FOR SERVICE

GENERAL PRECAUTIONS IN USE

A. Never operate the unit when it is empty.

Operating the oven with no load may shorten the
life of the magnetron. Whenever cooking dry foods
(dried fish, bread, etc.)or a small amount of food,
be sure to put a glass of water into the cooking
compartment. The glass turntable may become hot
after operating, be careful when touching it.

B. Aluminum foil should be avoided because it will

disrupt cooking and may cause arcing. However,
small pieces may be used to cover some parts of
food to slow the cooking. Any aluminum foil used
should never be closer than 2.5 cm to any side wall
of the oven.

TRIAL OPERATION

After installation, the following sequences and results
should be checked carefully.

A. Put a container filled with water (about 1 liter)into

the oven, and close the door tightly.

B. Set cooking time for 10 minutes by touching “1 ”

and then “0” three times.“1, 0, 0, 0” appears in the
display window.

C. Touch the START/ENTER key.

Make sure the cavity light comes on. The unit will
begin cooking and the display window will show the
time counting down by seconds.

D. After about 5 minutes, make sure the primary

interlock switch, the secondary interlock switch and
the interlock monitor switch operate properly by
opening and closing the door several times. Touch
the START/ENTER key each time the door is
closed.

E. Continue operating the unit. Two short and a long

beep sound signal is heard when the time is up.

The unit will shut off automatically.
F. Confirm the water is hot.
G. Finally, measure the output power according to

“POWER OUTPUT MEASUREMENT” on
page 7-3.

FEATURES AND SPECIFICATIONS
FEATURES

A. The safety systems incorporated in this model are:

(1) Primary interlock switch
(2) Secondary interlock switch
(3) Interlock monitor switch
(4) Choke system
(5) Oven cavity thermostat

(Note This thermostat located on the oven cavity
will open and stop the unit from operation only if
a high temperature is reached, such as, a fire
created by overcooking food.)

B. Any one of 10 power output levels ranging 0W to

850W can be selected by the touch control and
electronic computer system.

C. Cooking time can be displayed on the digital

readout.

D. Three different cooking stages (Include Defrost)

can be changes from one cooking stage to another.
This is made possible with the memory function of
the microprocessor.

6-1

SERVICE INFORMATION

PRECAUTIONS AND REPAIR SERVICE TIPS

PRELIMINARY

A. SINCE NEARLY 4000 VOLTS EXISTS IN SOME

CIRCUITS OF THIS UNIT REPAIRS SHOULD BE
CARRIED OUT WITH GREAT CARE.

The filament leads of magnetron carry High
Voltage with respect to ground. Extreme caution
must be exercised. Never plug the unit into a
power source to determine which component is
defective in high voltage section.

B. TO AVOID POSSIBLE EXPOSURE TO

MICROWAVE ENERGY LEAKAGE, THE
FOLLOWING PRECAUTIONS MUST BE TAKEN
BEFORE SERVICING.

(1) Before the power is applied:

(a) Make sure the primary interlock switch, the

secondary interlock switch and the interlock
monitor switch operate properly by opening
and closing the door several by opening and
closing the door several times.

(b) Make sure the perforated screen and the

dielectric choke of the door are correctly and
firmly mounted.

(2) After power is applied:

(a) Make sure the interlock switch mechanism

is operating properly by opening and closing
the door.

(b)

Check microwave energy leakage must be below
the limit of 5 mW/cm2.
(All service adjustments should be made for
minimum microwave energy leakage
readings).

(3) Do not operate the unit until it is completely

repaired, if any of the following conditions exist.

The unit must not be operated.
(a) The door does not close firmly.
(b) The hinge is broken.
(c) The door seal is damaged.
(d) The door is bent or warped, or there is any

other visible damage on the unit that may
cause microwave energy leakage.

NOTE: Always keep the seal clean.
(e) Make sure that there are no defective parts

in the interlock mechanism.

(f) Make sure that there are no detective parts

in the microwave generating and transmission
assembly (especially waveguide).

(4) The following items should be checked after the

unit is repaired:
(a) The interlock monitor switch is connected

correctly and firmly.

(b) The magnetron gasket is properly positioned

and mounted.

(c) The waveguide and the oven cavity are intact.

(no microwave energy leakage)

(d) The door can be properly closed and the

safety switches work properly.

(e) The unit must stop when the door is opened or

the time is up.

The unit must not be operated with any of the above
components removed or by-passed.

7-1

MICROWAVE LEAKAGE TEST

CAUTIONS

• Be sure to check microwave leakage prior to
servicing the oven if the oven is operative prior to
servicing.

• The service personnel should inform the
manufacture importer, or assembler of any certified
oven unit found to have a microwave emission level
in excess of 5 mW/cm2and should repair any unit

found to have excessive emission levels at no cost to
the owner and should ascertain the cause of the
excessive leakage. The service personnel should
instruct the owner not to use the unit until the oven has
been brought into compliance.

• If the oven operates with the door open, the service
personnel should;

- Tell the user not to operate the oven

- Contact the manufacturer and CDRH (Center for
Devices and Radiological Health)immediately.
NOTE: Address on CDRH

Office of Compliance (HFZ-312)
Center for Devices and Radiological Health
1390 Piccard Drive Rockville, Maryland 20850

• The service personnel should check all surface and
vent openings for microwave emission testing.

• Check for microwave energy leakage after every
servicing. The power density of the microwave
radiation leakage emitted by the microwave oven
should not exceed 1mW/cm.sq. And always start
measuring of an unknown field to assure safety for
operating personnel from radiation leakage.
NOTE: The standard is 5mW/cm.sq. while in the
customer’s home.1mW/cm.sq.stated here is
manufacturer’s own voluntary standard for units in
customer ’s home.

EQUIPMENT-

• TESTER ((VOLTS-DC, AC, Ohmmeter)

• Microwave survey meter

- Holaday HI-1500
HI-1501

- Narda 8100

8200

• 600 cc non conductive material beaker (glass or
plastic), inside diameter:approx.8.5 cm (31/2 in.)

• Glass thermometer: 100 °C or 212 °F (1 deg scale)

MEASURING MICROWAVE ENERGY
LEAKAGE

• Pour 275±15cc of 20±5°C(68±9°F) water in a beaker
which is graduated to 600 cc, and place the beaker
on the oven.

• Set the energy leakage monitor to 2,450 MHz and
use it following the manufacturer's recommended
test procedure to assure correct result.

• When measuring the leakage, always use the 2-inch
(5cm) spacer supplied with the probe.

• Operate the oven at its maximum output.

• Measure the microwave radiation using and
electromagnetic radiation monitor by holding the
probe perpendicular to the surface being measured.

Move probe along shaded area.

Probe scanning speed
Less than 2.5 cm/sec. ( 1 in/sec)

7-2

MEASUREMENT WITH THE OUTSIDE CASE
REMOVED

(1) When you replace the magnetron, measure for

microwave energy leakage before the outer case
is installed and after all necessary components
are replaced or adjusted. Special care should be
taken in measuring the following parts.

-Around the magnetron

-The waveguide

WARNING: AVOID CONTACTING ANY HIGH

VOLTAGE PARTS.

NOTE WHEN MEASURING

(1) Do not exceed meter full scale deflection.
(2) The test probe must be removed no faster than

1 inch/sec (2.5cm/sec)along the shaded area,
otherwise a false reading may result.

(3) The test probe must be held with the grip portion

of the handle. A false reading may result if the
operator’s hand is between the handle and the
probe.

(4) When testing near a corner of the door, keep

the probe perpendicular to the surface making
sure the probe is moved horizontally along the
oven surface.

MEASUREMENT WITH A FULLY
ASSEMBLED OVEN

(1) After all components, including the outer

panels, are fully assembled, measure for
microwave energy leakage around the door
viewing window, the exhaust opening and air
inlet openings.

(2) Microwave energy leakage must not exceed the

values prescribed below.

NOTES:

Leakage with the outer panels removed -less
than 5 mW/cm2.
Leakage for a fully assembled oven (“Before the
latch switch (primary)is interrupted”)with the door
in a slightly opened position -less than 1 mW/cm

2

POWER OUTPUT MEASUREMENT

(1) Microwave power output measurement is made

with the microwave oven supplied at its rated voltage and
operated at its maximum microwave power setting with a
load of (1000 ± 5)g of potable water.

(2) The water is contained in a cylindrical borosilicate

glass vessel having a maximum material thickness

1

of

/8” (3 mm)and an outside diameter of approximately

7.6” (190mm).

(3) The oven and the empty vessel are at ambient

Temperature(T0)prior to the start of the test.

(4) The initial temperature (T1)of the water is

(10 ± 1)°C (50 °F)It is measured immediately before the
water is added to the vessel. After addition of the water to
the vessel, the load is immediately placed on the center
of the turntable which is in the lowest position and the
microwave power switched on.

(5) The time t for the temperature of the water to rise

by a value T of (10 ± 1)°K is measured, where t is the
time in seconds and T is the temperature rise.
The initial and final water temperatures are selected so
that the maximum difference between the final water
temperature and the ambient temperature is 5 °K.

(6) The microwave power output P in watts is calculated

from the following formula :

RECORD KEEPING AND NOTIFICATION
AFTER MEASUREMENT

(1) After adjustment and repair of any microwave

energy interruption or microwave energy blocking
device, record the measured values for future
reference. Also enter the information on the
service invoice.

(2) Should the microwave energy leakage not be

more than 1 mW/cm2after determining that all
parts are in good condition, functioning properly
and genuine replacement parts which are listed in
this manual have been used.

(3) At least once a year, have the electromagnetic

energy leakage monitor checked for calibration
by its manufacturer.

4.187 Mw(T2 –T1)+0.55Mc(T2 –T0)

P =

is measured while the microwave generator is
operating at full power. Magnetron filament heat-up
time is not included. (about 3 sec)

(7) The water is stirred to equalize temperature

throughout the vessel, prior to measuring the final
water temperature.

(8) Stirring devices and measuring instruments are

selected in order to minimize addition or removal of
heat.

Where

P is the microwave power output, in watts:
Mw is the mass of the water, in grams:
Mc is the mass of the container, in grams:
T0 is the ambient temperature, in °C:
T1 is the initial temperature of the water, in °C:
T2 is the final temperature of the water, in °C:
t is the heating time in seconds, excluding the magnetron filament heat-up time.

WATER LOAD

7-3

t

GLASS TRAY

Circuit Board

DISASSEMBLY INSTRUCTIONS

Power Transformer

Control Panel

Screw

Circuit Board

(CN2)

(RY8)

(RY10)

(CN1)

(CN5)

(CN4)

(CN6)

Control Bracket

Circuit Board

FPC Connector(S1)

IMPORTANT NOTES:

UNIT MUST BE DISCONNECTED FROM ELEC­TRICAL OUTLET WHEN MAKING REPAIRS, RE­PLACEMENTS, ADJUSTMENTS AND CONTIN­UITY CHECKS. WAIT AT LEAST ONE MINUTE,
UNTIL THE HIGH VOLTAGE CAPACITOR IN THE
HIGH VOLTAGE POWER SUPPLY HAS FULLY
DISCHARGED.
THE CAPACITOR SHOULD BE DISCHARGED BY
USING INSULATED WIRE - I.E. TEST PROBE
CONNECTED TO 10K-OHM RESISTOR IN SERIES
TO GROUND.
WHEN RECONNECTING THE WIRE LEADS TO
ANY PART, MAKE SURE THE WIRING CONNE­CTIONS AND LEAD COLORS ARE CORRECTLY
MATCHED ACCORDING TO THE OVERALL CIR­CUIT DIAGRAM. (ESPECIALLY SWITCHES AND
HIGH VOLTAGE CIRCUIT.)

A. REMOVING POWER AND CONTROL

CIRCUIT BOARD (Figures 1, 2 and 3)

(1) Remove a screw securing the control panel

assembly to the oven cavity.
(2) Remove the control panel with pushing it upward.
(3) Remove the five connectors (CN1, CN2, CN4,

CN5) and wire leads (Relay8, Relay10) from the

circuit board.

(4) Remove 4 screws securing the circuit board.

Figure 2

(5) Remove the FPC connector from the terminal

socket following “HOW TO REMOVE THE FPC
CONNECTOR” on the next page.

(6) Remove the circuit board from the control bracket

carefully.

Figure 1

Figure 3

7-4

HOW TO REMOVE THE F.P.C. CONNECTOR

F.P.C.
Connector

Terminal
socket

Plastic

fastener

Holes

Hook

Plastic fastener

Terminal

socket

F.P.C.

Connector

Plastic
fastener

Terminal

socket

F.P.C.

Connector

Terminal

socket

Plastic fastener

Holes

Hook

HOW TO INSERT THE F.P.C. CONNECTOR

Follow the steps below as illustrated in Figures 4
and 5 to remove the F.P.C. connector.

(1) Hold the edges of the plastic fastener with

thumb and forefinger.
(Figure 4)

(2) Lift up the lever of the plastic fastener from

the terminal socket by lightly pressing the
lever end with forefinger.
(Figure 5)

(3) Remove the F.P.C. connector from the

terminal socket.

Follow the steps below as illustrated in Figures 6
and 7 to insert the F.P.C. connector.
(1) Insert the F.P.C. connector into the terminal

socket securely with the fingers.

(2) Hold the plastic fastener with thumb and

forefinger of the other hand, and push it
slowly into the terminal socket. (Figure 6)
NOTE: When reconnecting the F.P.C.

connector make sure that the holes
on the F.P.C. connector are properly
engaged with the hooks on the plastic
fastener

(3) Lock the level of the plastic fastener into the

hook of the terminal socket securely by
releasing the fingers.
(Figure 7)

Figure 4

Figure 6

Figure 5

Figure 7

7-5

B. REMOVING THE OUTSIDE CASE

(Figure 8)

(1) Remove the vent grille by removing two screws

securing it to the outside case.
(2) Remove two screws securing it to the air duct.
(3) Remove the mounting plate by turning the screws

(1 or 2 screws)securing it to the out case.
(4) Remove two screws on the left central edge and

one screw on the right central edge of Base plate.

Remove the Mount, All from the outside case by

removing one screw securing it to the outside case.
(5) Remove six screws of the rear cavity.
(6) Remove the outside case.

Mount,All

Door

Vent Grille

Figure 8

Controller

(1 or 2 screws)

Mounting
Plate

Out Case

(3 screws)

7-6

C. REMOVING THE DOOR INTERLOCK

Latch Board

Primary Interlock Switch

Monitor Interlock Switch

Secondary Interlock Switch

Latch Board

Primary
Interlock Switch

Monitor
Interlock Switch

Secondary
Interlock Switch

SWITCHES (Figures 9, 10)

(1) Disconnect the wire leads from the interlock

switches.
(2) Remove two screws securing the Latch Board.
(3) Make necessary replacements and check

microwave energy leakage according to

“ADJUSTMENT PROCEDURES” on page 7-12.

Figure 9

Figure 10

7-7

D. REMOVING MAGNETRON

(Figures 11 Through 13b)

(1) Remove the vent grille by loosening two screws.

(Figure 11)
(2) Remove the outside case. See page 7-6.
(3) Remove four tap tite screws securing the

magnetron to the wave guide.
(4) Disconnect the leadwire.
(5) Remove the magnetron VERY CAREFULLY.

NOTES:

• When removing the magnetron, make sure that its
dome does not hit any adjacent parts, or it may be
damaged.

• When replacing the magnetron, be sure to install the
magnetron gasket in the correct position and be sure
that the gasket is in good condition.

• After replacing the magnetron, check for microwave
energy leakage with a survey meter Check
microwave energy leakage must be below the limit
of 5 mW/cm2. (All service adjustments should be
made for minimum microwave energy leakage
readings.)

Mount,All

Figure 11

Door

Vent Grille

Controller

Figure 12

(3 screws)

(1 or 2 screws)

Mounting
Plate

Out Case

Figure 13-a Figure 13-b

7-8

E. REMOVING STIRRER FAN

Figure 15

Figure 14

Figure 18

Door Screen

Figure 19

(Figures 14 and 15)

(1) Remove two screws securing it to the oven

upper plate by using drive screw.
(2) Rotate slightly and pull out the stirrer fan cover.
(3) Remove the stirrer fan.

F. REMOVING DOOR (Figure 16)

(1) Remove the vent grille by removing two screws

securing it to the outside case loosening.

(2) Lift up and remove the door.

NOTES:

• After replacing the door, be sure to check that the
primary interlock switch, the secondary interlock
switch and the interlock monitor switch is in good
operating normally.

• After replacing the door, check for microwave energy
leakage with a survey meter. Microwave energy
leakage must be below the limit of 5mW/cm2. (With a
275 ml water load)

G. DISASSEMBLING DOOR (Figure 17)

(1) Remove the dielectric choke by using knife

blade or small screw driver, etc.

(2) Remove two screws securing it to the door handle.

CAUTION: Be careful not to damage door seal

plate with the screwdriver.

7-9

H. ASSEMBLING DOOR

Space

Figure 19-c

(1 or 2 screws)

MOUNT, ALL

Figure 18

Figure 19-a

Figure 19-b

(1) When mounting the door assembly to the oven

assembly, be sure to adjust the door assembly
parallel to the chassis. Also adjust so the door has no
play between the inner door surface and oven frame
assembly. If the door assembly is not mounted
properly, microwaves may leak from the clearance
between the door and the oven.

I. REMOVING THE VENTILATION MOTOR

(1) Remove the mounting plate by loosening

mounting plate screws (1 or 2 screws)
securing it to the back plate.
(See Figure 18)

(2) Remove MOUNT, ALL by loosening one screw

securing the ventilation Motor and back plate.
(See Figure 19-a)

(3) Carefully pull the ventilation motor ASS'Y out of

the microwave oven. (See Figure 19-b)

J. REPLACING THE HUMIDITY SENSOR

(For sensor model only)

(1) Remove the sensor by removing two screws

securing it to the air duct. (See Figure 19-c).

(2) Mount the new humidity sensor to the air duct.

7-10

K. REMOVING THE TURNTABLE MOTOR

(1) Remove the turntable.
(2) Remove the turntable shaft VERY CAREFULLY

with a slotted screwdriver. (Figure 21)

(3) Remove the base plate by removing 7 screws

securing it to the oven cavity. (Figure 22-a)

(4) Disconnect the leadwire from the turntable motor

terminals.

(5) Remove the 2 screws securing the turntable motor

to the oven cavity ASS'Y. (Figure 22-b)

Figure 20

L. REMOVING CONVECTION HEATER

AND THERMISTOR (Figure 23)

(1) Remove the out case.
(2) Remove the air duct by removing six screws

securing it to the oven front plate, guide air and

glasswool-L cover.
(3) Disconnect the wire leads of air duct.
(4) Remove the magnetron.
(5) Remove the latch board assembly.
(6) Remove the bottom plate by removing four screws.
(7) Remove the four net screws securing chamber

assembly.
(8) Lift the chamber assembly from the oven cavity.
(9) Remove three screws securing the heater of the

chamber assembly.
(10) Lift the convection heater from the chamber

assembly.

Figure 21-a

Wire Leads

Turntable Motor

Figure 22-b

NOTES:

• Remove the leadwire from the turntable motor
VERY CAREFULLY.

• Be sure to grasp the connector not the wires when
removing.

Figure 23

7-11

INTERLOCK SYSTEM

Interlock
Monitor Switch

LATCH

LATCH BOARD

0-1/64"

0-1/64"

Latch Board

Primary
Interlock Switch

Secondary
Interlock Switch

INTERLOCK MECHANISM

The door lock mechanism is a device which has been specially designed to eliminate microwave activity when the
door is opened during cooking and thus to prevent the danger resulting from the microwave leakage.

ADJUSTMENT PROCEDURES

To avoid possible exposure to microwave energy
leakage, adjust the door latches and interlock
switches, using the following procedure.

The Interlock Monitor and Primary Interlock Switch act
as the final safety switch protecting the user from
microwave energy. The terminals between “COM” and
“NC” of the Interlock Monitor must close when the door
is opened. After adjusting the Interlock Monitor Switch,
make sure that it is correctly connected.
Mounting of the primary/monitor/secondary switches to
the latch board.

CHECK THE DOOR LATCH AND SWITCH
CLOSING.

NOTE:

The outer cover of the microwave oven is
removed.

(1) Set the microwave oven on its side so that you can

see the latch board and the switches, as shown in
Figure 23-a.

(2) Close the door tightly and check gaps A and B to

be sure they are no more than 1/64” (0.5 mm).
See Figure 23-b for close-up view of gaps A and B
(door latches). If all gaps are less than 1/64”
(0.5 mm), adjustment of the latch board may not
be necessary. Go to Steps 5 and 6 to check the
sequence of the switches.

NOTE:

If any gap is larger than 1/64” (0.5 mm), you will
need to adjust the latch board”. Go to step 3
and follow all steps in order.

ADJUST THE LATCH AND SWITCH CLOSING

(3) Loosen the two screws holding the plastic latch

board as shown.

(4) With the oven door closed tightly, move the latch

board upward toward the top of the oven and/or
away from the door latch until the gaps are less
than 1/64 ” (0.5 mm).
Hold the latch board tightly in this position until you
check the sequence of the switches in steps 5
and 6.

Figure 23-a

Figure 23-b

7-12

TEST THE LATCH AND SWITCH SEQUENCE

(5) Open the oven door slowly. Watch the door latch,

the Secondary Switch. Release Rod and Lever
on the switches to make sure they are zero to the
body of the switches in the following sequence:

-Primary Interlock Switch

-Secondary Interlock Switch

-Interlock Monitor Switch

Adjust the latch board until the switches operate in

this sequence. See Steps 3 and 4.

(6) Close the oven door slowly and be sure it is tightly

closed. Watch the three switches to make sure
they are zero to the body of the switches in the
following sequence:

-Interlock Monitor Switch

-Primary Interlock Switch

-Secondary Interlock Switch

NOTE: The Interlock Monitor Switch is an added

safety check on the Primary and
Secondary Interlock Switches. If the
Primary and Secondary Interlock Switches
allow the oven to operate with the door
open, the Monitor Switch will blow the
fuse.

(7) When you achieve the proper sequence of

switches in Steps 5 and 6, tighten the latch board
screws at that point.

TEST THE MICROWAVE ENERGY LEAKAGE

Make sure the microwave energy leakage is below the
limit of 1mW/cm
5mW/cm

2

2

(with a 275 ml water load) and

(with a 275 ml water load without the

cabinet) when measured with a survey meter.

7-13

INTERLOCK CONTINUITY TEST

A. PRIMARY INTERLOCK SWITCH TEST

When the door is opened slowly, an audible click
should be heard at the same time or successively
at intervals and the latches should activate the
switches with an audible click
If the latches do not activate the switches when the
door is closed, the switches should be a adjusted
in accordance with the adjustment procedure.
Disconnect the wire lead from the primary switch.
Connect the ohmmeter leads to the common
(COM)and normally open (NO)terminal of the
switch. The meter should indicate an open circuit
in the door open condition.
When the door is closed, the meter should indicate
a closed circuit.
When the primary switch operation is abnormal,
make the necessary adjustment or replace the
switch only with the same type of switch.

B. SECONDARY INTERLOCK SWITCH TEST

Disconnect the wire lead from the secondary
switch.
Connect the ohmmeter leads to the common
(COM)and normally open (NO)terminals of the
switch. The meter should indicate a open circuit in
the door open condition. When the door is closed,
meter should indicate an closed circuit. When the
secondary switch operation is abnormal, make the
necessary adjustment or replace the switch only
with the same type of switch.

C. MONITOR SWITCH TEST

Disconnect the wire lead from the monitor switch.
Connect the ohmmeter leads to the common
(COM)and normally closed (NC)terminals of the
switch. The meter should indicate closed circuit in
the door open condition. When the door is closed,
meter should indicate an open circuit. When the
monitor switch operation is abnormal, replace with
the same type of switch.

NOTE: After repairing the door or the interlock
system, it is necessary to do this continuity
test before operating the oven.

COMPONENTS TEST PROCEDURE RESULTS

SWITCHES Check for continuity of the Door Door
(Wire leads removed) switch with an Ohm-meter open closed

Primary

Switch

Monitor

Switch

Secondary

Switch

COM

COM

NO

NC

COM

NO

NOTE : After checking for the continuity of switches, make sure that they are

connected correctly.

WARNING : FOR CONTINUED PROTECTION AGAINST EXCESSIVE RADIATION

EMISSION, REPLACE ONLY WITH IDENTICAL REPLACEMENT PARTS.

TYPE NO.SZM-V16-FA-63 OR VP-533A-OF OR V-5230Q FOR PRIMARY SWITCH
TYPE NO.SZM-V16-FA-62 OR VP-532A-OF OR V-5220Q FOR MONITOR SWITCH
TYPE NO.SZM-V16-FA-63 OR VP-533A-OF OR V-5230Q FOR SECONDARY SWITCH

7-14

TEST AND CHECKOUT PRECEDURES AND TROUBLESHOOTING

CAUTIONS

1. DISCONNECT THE POWER SUPPLY CORD FROM THE OUTLET WHENEVER REMOVING THE OUTER CASE
FROM THE UNIT. PROCEED WITH THE TEST ONLY AFTER DISCHARGING THE HIGH VOLTAGE CAPACITOR
AND REMOVING THE LEAD WIRES FROM THE PRIMARY WINDING OF THE HIGH VOLTAGE TRANSFORMER.

2. ALL OPERATIONAL CHECKS WITH MICROWAVE ENERGY MUST BE DONE WITH A LOAD (1 LITER OF
WATER IN CONTAINER)IN THE OVEN.

A. TEST PROCEDURES

COMPONENTS TEST RESULTS

TRANSFORMER

MAGNETRON

FILAMENT
WINDING

SECONDARY
WINDING

PRIMARY
WINDING

1. Remove wire leads.

2. Measure resistance. (ohm meter scale: Rx1)

• Primary winding

• Secondary winding

• Filament winding

3. Measure resistance. (ohm meter scale: Rx1000)

• Primary winding to ground

• Filament winding to ground

Antenna

Gasket

Approx. 0.3 to 0.5 ohms
Approx. 65 to 120 ohms
0 ohm

Normal: Infinite
Normal: Infinite

Chassis

1. Remove wire leads. Install the magnetron seal
in the correct position. Check that the seal is in
good condition.

2. Measure resistance. (ohm meter scale: Rx1)

• Filament terminal

3. Measure resistance. (ohm meter scale: Rx1000)

• Filament to chassis

7-15

Normal: Less than 1 ohm

Normal: Infinite

COMPONENTS TEST RESULTS

CAPACITOR

DIODE

Some inexpensive meters
may indicate infinite
resistance in both directions.

RELAY 8

1. Remove wire leads.

2. Measure resistance.
(ohm meter scale: Rx1000)

• Terminal to terminal

• Terminal to case

1. Measure continuity. Forward.
(ohm meter scale: Rx1000)

2. Measure continuity. Reverse.
(ohm meter scale: Rx1000)

1. Measure continuity.
(ohm meter scale: Rx1)

2. Remove the lead wires and operate oven at

power level 1 through power level 10.

Normal:
Momently indicates
several ohm, and then
gradually returns to infinite
Normal: Infinite.

Normal:Continuity.
Abnormal: Infinite.

Normal: Infinite.
Abnormal: Continuity.

Power

Level

10

1

4 Sec

2

6 Sec

3

8 Sec

4

10 Sec

5

12 Sec

6

14 Sec

7

16 Sec

8

18 Sec

9

20 Sec
22 Sec

18 Sec
16 Sec
14 Sec
12 Sec
10 Sec

8 Sec
6 Sec
4 Sec
2 Sec
0 Sec

RELAY 10

FAN MOTOR
CIRCULATION MOTOR

1. Measure continuity.
(ohm meter scale: Rx1)

2. Remove the lead wires and operate
oven at Convection Cooking.

1. Remove wire leads.

2. Measure resistance.
(ohm meter scale: Rx1)

7-16

Convection

Cooking Start

Normal:
Approximately

Fan Cir

35-55 ohm 25-40 ohm

ohm
Abnormal:
Infinite or several.

OFF

COMPONENTS TEST RESULTS

1
2
3

VENTILATION MOTOR

DAMPER MOTOR (D.M)
TURNTABLE MOTOR (T.M)
STIRRER MOTOR (S.M)

THERMISTOR

1. Remove wire leads.

2. Measure resistance.
(ohm meter scale: Rx1)

1. Remove wire leads.

2. Measure resistance.
(ohm meter scale: Rx1000)

1. Remove the connector from PCB

2. Measure resistance across pins 1 & 3.
(ohm meter scale: Rx1)

Normal:
Approximately
60 to 80 ohm

Normal:Approximately

D.M T.M S.M

2.3-3.5 2.6-3.5 100-170
Kohm Kohm ohm

Abnormal:
Infinite or several.

Normal:
Approximately 250 to 350
Kohm at 68 ± 35°F
Abnormal:
Infinite or several.

HEATER ELEMENT

SENSOR

1. Remove wire leads.

2. Measure resistance.
(ohm meter scale:Rx1)

1. Remove the 3 pin connector from PCB.

2. Measure resistance across pins 1 & 2.

3. Across pins 2 & 3.
(ohm meter scale:Rx1)

Normal: Approximately

Conv. HTR

7-14

Abnormal:
Infinite or several.

Normal: Approximately

1 & 2 2 & 3

3.1 Kohm ∞

at 68 ± 35°F
Abnormal:
Infinite or several.

7-17

COMPONENTS TEST RESULTS

1
2
3
4
5
6
7
8
9
10
11
12
13

4

MICRO.

DEFROST

AUTO

N.C

TIMER

KITCHEN

START

ENTER/

POPCORN

POWER

N.C

COOK

AUTO

COOK

CLEAR

STOP/

REHEAT

TURNTABLE

ON/OFF

ON/OFF 5-SPEED

SENSOR

SENSOR

N.C N.C

SENSOR

ON/OFF

LIGHT

1

2

3

N.C

AUTO

8

30 SEC.

CLOCK

9

0

MORE

COMBI

LESS

SOFTEN

SPEED

TIME SET

ADD

AUTO

CONV.

MELT

N.C

COMBI.

5

6

7

(VENT) (VENT)

(VENT)

CUSTOM

SET

CUSTOM

COOK

13

12

11

10

9

8

1

2

3

4

5

6

7

TOUCH KEY BOARD

Measure the resistance between terminal
pins of KEY CONNECTOR.

NOTE:

When reconnecting the FPC connector,
make sure that the holes on the FPC
connector are properly engaged with hooks
on the plastic fastener.

MATRIX CIRCUIT FOR

TOUCH KEY BOARD

CONNECTOR(KEY CON)

When

Resistance

value

touched

Less than
400 ohms

FPC CONNECTOR

Top

When not
touched

More than
1 mega ohm

NOTES:

• A MICROWAVE ENERGY TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS SERVICED FOR
ANY REASON.

• MAKE SURE THE WIRE LEADS ARE IN THE CORRECT POSITION.

• WHEN REMOVING THE WIRE LEADS FROM THE PARTS, BE SURE TO GRASP THE CONNECTOR, NOT
THE WIRES.

7-18

B. CHECKOUT PROCEDURES

(1) CHECKOUT PROCEDURES FOR FUSE BLOWING

CAUTION: REPLACE BLOWN FUSE WITH 20 AMPERE FUSE.

PROBLEMS CAUSES

Fuse blows immediately after
the door is closed.

Improper operation of the primary interlock, secondary

Fuse blows immediately after
the door is opened.

interlock switches and/or the interlock monitor switch.

Fuse blows when the door is closed and
START/

NOTES:

• If the fuse is blown by an improper switch operation, replace all switches and the fuse at the same time.
After replacing the defective switches with new ones, make sure that they are correctly connected.

• Check for microwave energy leakage according to INTERLOCK ADJUSTMENT PROCEDURES on page
7-12 when the primary interlock, secondary interlock switches and/or the interlock monitor switches are
adjusted or replaced.

ENTER

key is touched.

Malfunction of the high voltage transformer; the high
voltage capacitor including the diode, the magnetron,
the blower motor or the circuit board.

7-19

(2)CHECKOUT PROCEDURES FOR RELAY.

-PROBLEM (A)-

FAN motor turns on without touching START/ENTER

key when the door is closed.

GOOD

NO

Remove the mate connector of I/O
CON from the circuit board.
Does the unit still operate?

NO

Replace the
circuit board

YES

YES

Defective

Wire Assembly

Replace

Wire Assembly

-PROBLEM (A)--

Oven lamp turns on without touching START/ENTER

key when the door is closed.

NO

GOOD

Remove the mate connector of I/O
CON from the circuit board.
Does the unit still operate?

NO

Replace the
circuit board

YES

YES

Defective

Wire Assembly

Replace

Wire Assembly

-PROBLEM (B)-

FAN motor turns on When the door is closed and

START/ENTER key is touched.

GOOD

YES

Measure the voltage at pin NO.
1,10 of CN1
Voltage reading:120 V AC

NO

Replace the
circuit board

NO

YES

Defective
FAN motor

Replace

FAN motor.

-PROBLEM (B)-

Oven lamp turns on When the door is closed and

START/ENTER key is touched.

YES

GOOD

Measure the voltage at pin NO.
1,10 of CN1
Voltage reading:120 V AC

NO

Replace the
circuit board

NO

YES

Defective
Oven lamp

Replace

Oven lamp

7-20

(3) CHECKOUT PROCEDURES FOR CIRCUIT

BOARD
The following symptoms indicate a defective circuit
board.

1) The start function fails to operate but the high
voltage Systems, the interlock switches, the door
sensing and the relay check good.

2) The unit with a normal relay continuously operates.

3) Proper temperature measurement is not obtained.

4) The buzzer does not sound or continues to sound.

5) Some segments of one or more digits do not light
up, or they continue to light up, or segments light
when they should not.

NOTE: A MICROWAVE ENERGY LEAKAGE TEST MUST ALWAYS BE PERFORMED WHEN THE UNIT IS

SERVICED FOR ANY REASON.

6) Wrong figures appear.

7) The figures of all digits.

8) Some of the indicators do no flicker light up.

9) The clock does not keep time properly.

7-21

C. TROUBLE SHOOTING

WHEN YOU GET A COMPLAINT FROM YOUR CUSTOMER, EVALUATE THE COMPLAINT CAREFULLY. IF THE
FOLLOWING SYMPTOMS APPLY, PLEASE INSTRUCT THE CUSTOMER IN THE PROPER USE OF THE TOASTER AND
MICROWAVE OVEN. THIS CAN ELIMINATE AN UNNECESSARY SERVICE CALL.

CAUTIONS

1. Check grounding and cool this unit before checking for trouble.

2. Be careful of the high voltage circuit.

3. Discharge the high voltage capacitor.

4. When checking the continuity of the switches or of the high voltage transformer, disconnect one lead wire from these
parts and then check continuity with the AC plug removed. To do otherwise may result in a false reading or damage
to your meter.

5. Do not touch any part of the circuit on the PCB since static electric discharge may damage this control panel.
Always touch yourself to ground while working on this panel to discharge any static charge built up in your body.
(Micom model only)

CONDITION

Microwave oven

does not work.

Output power is too low. Low AC input voltage.

Sparks occur in oven.

Inserting many plugs into one
outlet and using them at the
same time.
(blown fuse or breaker)

Plug is not inserted tightly.

Food temperature is too low.

Using metallic ware and
allowing it to touch the oven
wall.

CAUSE REMEDY

Avoid using other electrical
appliances when you use this
unit.

Insert plug securely.

Use the microwave oven at
adequate line voltage.

This may not be a defect.
It is possible that the food
should be cooked for a
longer time period.

Do not use metallic ware for
cooking except where noted
in the cooking guide.

Uneven microwave cooking.

Ceramic ware trimmed in
gold or silver powder is used.

Inconsistent intensity of
microwave by their
characteristics.

7-22

Do not use any type of
cookware with metallic
trimming.

1. Use plastic wrap or lid.

2. Stir once or twice while
cooking soup, cocoa or
milk, etc.

(TROUBLE 1) The following visual conditions indicate a probable defective control circuit.

1. Incomplete segments.

• Segment missing.

• Partial segment missing.

• Digit flickering (NOTE: Slight flickering is normal.)

2. Colon does not turn on or blink.

3. A distinct change in the brightness of one or more numbers in display.

4. One or more digits in the display are not lighting.

5. Display indicates a number different from one touched, for example, key in 5 and 3 appears in the display.

6. Specific numbers (for example 7 or 9) will not display when key pad is touched.

7. Display does not count down with time blinking or up with clock operation.

8. Display obviously jumps in time while counting down.

9. Display counts down too fast while cooking.

10. Each indicator light does not turn on after setting cooking cycle.

11. Display time of day does not reappear when cooking is finished.

CONDITION CHECK RESULT CAUSE REMEDY

1. No input can be
programmed.

2. Some inputs
cannot be
programmed.

3. Display shows a
number or figure
different from one
touched.

4. Random
programming
when touching
other pads.

5. Display is fixed
at some figure
and can not
accept any
input.

Check the conn­ection between
membrane key
assembly and
PCB assembly.

Replace key
membrane
assembly and
check operation.

Continuity.

No continuity.

Everything works
as specified.

Still have trouble.

Defective PCB
assembly.

Loose
connection.

Defective key
membrane
assembly.

Defective PCB
assembly.

Replace PCB
assembly.

Connect them
tightly.

Replace key
membrane
assembly.

Replace PCB
assembly.

7-23

(TROUBLE 2) Microwave oven does not operate at all, Display window does not display any figures,

and no input is accepted.

CONDITION CHECK RESULT CAUSE REMEDY

1. Fuse blows. Continuity.

Check continuity
of monitor
switch (with
door closed).

Replace fuse

Check continuity
of primary
switch (with
door opened).

Disconnect one
side of the wire
lead connected
from transformer
to the high
voltage
capacitor and
operate the unit.

No continuity.

Continuity.

No continuity.

Normal.

Fuse blows again

Malfunction of the
monitor switch.

Shorted contact at
the primary switch.

Defective high
voltage capacitor.

Defective high volt­age transformer.

Replace fuse,
primary, monitor
switches, and
RELAY(RY8) of
P.C.B Assembly.

Replace fuse,
primary, monitor
switches, and
RELAY(RY8) of
P.C.B Assembly.

Replace high
voltage capacitor.

Replace high volt­age transformer.

2. Fuse does not
blow.

Check continuity
of magnetron
thermostat.

Check continuity
of power supply
cord.

No continuity.

Continuity.

No continuity.

7-24

Defective
thermostat.

Defective power
supply cord.

Replace
thermostat.

Replace power
supply cord.

(TROUBLE 3) Display shows all figures set, but oven does not start cooking while

desired program times are set and START

/ENTER

pad is touched.

CONDITION CHECK RESULT CAUSE REMEDY

1.Setting time does

not count down
when touching
START/ENTER
pad.

2. Fan motor or
oven lamp
do not turn
on.

Check continuity
of secondary
switch (with
door closed).

Check the con­nection between
CN1 connector
and PCB
assembly.

Check fan motor.

Check oven lamp.

No continuity.

Continuity.

No continuity.

Continuity.

Abnormal.

Abnormal.

Normal.

Defective
secondary switch.

Defective P.C.B
assembly.

Loose connection.

Defective fan
motor.

Defective oven
lamp.

Replace
secondary switch.

Replace P.C.B
assembly.

Connection then
tightly.

Replace fan
motor.

Replace oven
lamp.

(TROUBLE 4) Oven seems to be operation but little heat is produced in oven load.

CONDITION CHECK RESULT CAUSE REMEDY

Output is low.

Check the
power source
voltage.

Disconnect the
wire leads from
relay 8 and check
on and off time
with multitester.

Measure the
output power.

Lower than 90% of
rating voltage.

Normal.

Abnormal.

Normal.

Abnormal.

NOTE : Simple test of power output-conducted by heating one liter water for one min. if available.

Minimum 8.5°C temperature rise is normal condition.

7-25

Decrease in power
source voltage
with load.

Defective P.C.B
assembly.

Defective
magnetron.

Suggest customer
contact local
electric power
utility co. or
qualified
electrician.

Replace P.C.B
assembly.

Replace
magnetron.

(TROUBLE 5)

No microwave oscillation even though oven lamp and fan motor run

(Display operates properly)

CONDITION CHECK RESULT CAUSE REMEDY

No microwave
oscillation.

Disconnect the
wire leads from
relay 8 and
check continuity
of relay 8.
(Operate the
unit)

Check high vol­tage transformer

Check high vol­tage capacitor.

Check high vol­tage diode.

No continuity.

Continuity.

Abnormal

normal

Abnormal

normal

Abnormal

Defective P.C.B
assembly

Defective high
voltage
transformer.

Defective high
voltage capacitor.

Defective high
voltage Diode.

Replace P.C.B
assembly

Replace high
voltage
transformer .

Replace high
voltage capacitor.

Replace high
voltage Diode.

normal

Check
Magnetron.

NOTE: * Make sure the wire leads are in the correct position.

* When removing the wire leads from parts be sure to grasp the connector not the wires.
* When removing the magnetron, be sure to install the magnetron gasket in the correct position

and in good condition.

Output is full power
when you set lower
power level.

Disconnect the
wire leads from
relay 8 and check
continuity relay 8.
(Operate the unit)

Abnormal

Abnormal.

7-26

Defective
magnetron.

Defective PCB
assembly.

Replace
magnetron .

Replace PCB
assembly.

(TROUBLE 6) Convection oven does not operate at all or convection cook is bad.

CONDITION CHECK RESULT CAUSE REMEDY

Convection indicator
light but oven does
not go into cook cycle
when START/ENTER
pad is touched.

Temperature in
the oven cavity is
lower or higher
than preset.

Check the Relay
10 of P.C.B.
assembly.

Check the
connection between
P.C.B. assembly and
headwire connector.

Check the Relay
10 of P.C.B.
assembly.

Check the
convection heater
element.

Abnormal.

Normal.

No continuity.

Abnormal.

Normal.

Abnormal.

Normal.

Defective Relay

10.

Loose connection.

Defective Relay

10.

Defective
convection heater.

Replace Relay

10.

Connect them
tightly.

Replace
Relay 10.

Replace
convection heater.

Check the
circulation motor.

Check the
thermistor.

Check the Rack.

Abnormal.

Normal.

Error message
shows in the display.

Normal.

Cook on the
glass tray.

7-27

Defective
circulation motor.

Thermistor open
or short.

Without
metal rack.

Replace
circulation motor.

Replace
thermistor.

Cook with
metal rack.

INTERIOR PARTS

INSTALLATION PARTS

OVEN CAVITY PARTS

DOOR PARTS

LATCH BOARD PARTS

CONTROL PANEL PARTS

#EV#

EXPLODED VIEW

INTRODUCTION

8-1

#EV#

DOOR PARTS

1005

1004

1000

W200

1381

1009

1701

1006

W201

1007

1702

8-2

#EV#

CONTROLLER PARTS

2004

2381

2006

W105

2008

* 07

8-3

#EV#

OVEN CAVITY PARTS

3024

W142

3010

W105

3009

3031

3001

3029

3103

3057

W109

6000

9000

3032

3025

3026

8-4

W178

3011

3005

5382

6001

W202

3037

W121

#EV#

LATCH BOARD PARTS

4001

4000

4002

W111

4003

4002

4004

8-5

#EV#

INTERIOR PARTS (I)

3002

5411

3044

3012

3008

W125

3048

5024

W119

W124

W109

W141

5403

W121

3206

5062

3207

W109

W121

W101

5021

5023

W105

5409

5029

5067

5003

5035

5007

5008

W109

5002

5012

5009

W110

5052

5000

5018

W101

3006

W109

5407

W124

W121

W141

3208

5402

5401

W108

9002

9001

5028

W105

W105

3049

W117

8-6

4003

W123

5068

W105

W123

5705

W121

W101

5019

5404

#EV#

INTERIOR PARTS (II)

W136

5011

3021

5016

W136

W109

W109

W109

3051

3027

5037

W178

5382

W202

5412

5800

5056

W172

5045

W106

5006

5385

W109

W140

5010

5001

5041

5410

5014

W140

8-7

#EV#

INSTALLATION PARTS

6008

6011

6010

6009

USE

&

CARE

*01

INSTALLATION

MANUAL

*04

COOKING

GUIDE
LABEL

8-8

*05

WALL

TEMPLATE

UPPER

TEMPLATE

VINYL

BAG

*06-2*06-1

P/NO : MFL07543202

March, 2008

Printed in Korea