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Unlike many other appliances, the microwave oven is high-voltage, 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.  The microwave oven is

    designed to be used when grounded.  When it is inoperative, make

    sure it is grounded properly before beginning repair work.

CAUTION
Servicemen  should  remove  their  watches  whenever
working close to or replacing the magnetron.

This High Voltage Inverter Power Supply circuit supplies

very high voltage and very high current for the magnetron

tube.  Though it is free from danger in ordinary use, extreme

care should be taken during repair.  As you can see, it looks

like  a TV  flyback  transformer,  however  the  current  is

extremely large and so danger exists because of its high

current and high voltages.

The aluminum heat sink is also energized with high voltage

(HOT), so do not touch when AC input terminal is connected

to the power line because one of the IGBT  switching power

devices (Collector) is directly connected to the Aluminum

heat sink.

The Aluminum heat sink may be HOT from heat energy;

therefore, extreme care should be taken during servicing

and replacing.

Check the High Voltage Inverter Power Supply circuit grounding.

This High Voltage Inverter Power Supply circuit board must have

a proper chassis ground by the grounding bracket to the chassis

ground; otherwise, this H.V. Inverter circuit board will expose

very high voltage and cause extreme DANGER!  Be sure to have

proper grounding by the grounding plate and screws.

Warning about the electric charge in the high voltage capacitors.
For about 30 seconds after the oven is turned off, an electric charge
remains in the high voltage capacitors in the inverter power supply
circuit board.
When replacing or checking parts, remove the power plug from
the outlet and short the Inverter output terminal of the magnetron
filament terminals to the chassis ground with an insulated handle
screwdriver to discharge.  Please make sure to touch chassis
ground side first then short to the output terminals.

There is high-voltage present, with high-current capabilities in the

circuits of the primary, and secondary windings, choke coil and

heat sink of the Inverter.  It is extremely dangerous to work on or

near these circuits with oven energized.

DO NOT measure the voltage in the high voltage circuit including

filament voltage of magnetron.

Never touch any circuit wiring with your hand nor with an

insulated tool during operation.

(A) This is mandatory. Refer to “Measurements and Adjustments”

for these switches.

(B) When replacing the fuse, confirm that it has the appropriate

rating for these models.

(C) When replacing faulty switches, be sure mounting tabs are

not bent, broken or otherwise deficient in their ability to hold

the switches.

Never insert a wire, nail or any other metal object through the

lamp holes on the cavity or any other holes or gaps, because

such objects may work as an antenna and cause microwave

leakage.

When the 18 Amp. fuse if blown due to the operation of

short switch, you must replace Primary latch switch and

short switch. Also replace power relay B (RY1) when the

continuity check reads shorted contacts (1-2).

MAGNETRON

FILAMENT TERMINAL

INSULATED  HANDLE

SCREWDRIVER

Touch chassis side first then short to the terminal of the magnetron

filament terminal.

- 8 -

(A) After repair or replacement of parts, make sure that the screws of the

oven, etc. are neither loose nor missing.

Microwaves might leak if screws are not properly tightened.

(B) Make sure that all electrical connections are tight before inserting the

plug into the wall outlet.

(C) Check for microwave energy leakage. (Refer to procedure for measuring

microwave energy leakage.)

DO  NOT  BECOME  EXPOSED  TO  RADIATION  FROM  THE

MICROWAVE GENERATOR OR OTHER PARTS CONDUCTING

MICROWAVE ENERGY.

1. The following components have potentials above 250V while the

appliance is operating..

h Magnetron

h High voltage transformer (Located on Inverter (U))

h High voltage diodes (Located on Inverter (U))

h High voltage capacitors (Located on Inverter (U))

Pay special attention on these portions.

2. When the appliance is operated with the door hinges or magnetron

fixed incorrectly, the microwave leakage can reach more than

5mW/cm

2

. After repair or exchange, it is very important to check if

magnetron and the door hinges are correctly fixed.

- 9 -

*
*
*
*

- 10 -

(A) Discharge the high voltage capacitors, as mentioned and shown on page 11.

(B) Remove 1 screw holding air guide c to magnetron.

(C) Disconnect 2 high voltage lead wires from magnetron filament terminals.

(D) Remove 4 screws holding the magnetron.

NOTE: After replacement of the magnetron, tighten mounting screws in an X

pattern, properly making sure there is no gap between the waveguide

and the magnetron to prevent microwave leakage.

NOTE: Be sure to ground any static electric charge built up on your body before

handling the DPC.

(A) Disconnect all connectors from D.P.C.

(B) Slide the escutcheon base upward slightly.

(C) Remove 1 screws holding DPC

(F) Push the upper part of key board (display window portion) from back of

escutcheon base and peel off escutcheon sheet and membrane key

board completely from escutcheon base.

NOTE: 1. The membrane key board is attached to the escutcheon base with

double faced adhesive tape. Therefore, applying hot air such as using a

hair dryer is recommended for smoother removal.

2. When installing new membrane key board, make sure that the surface

of escutcheon base is cleaned sufficiently so that any problems (shorted

contacts or uneven surface) can be avoided.

3. Alignment position of membrane key board is as follows;

Membrane key board: Right and upper edges

Escutcheon sheet: Right and upper edges

NOTE: Be sure to ground any static electric charge built up on your body before

handling the DPC.

(A) Using solder wick or a desoldering tool and 30W soldering iron, carefully

remove all solder from the terminal pins of the low voltage transformer

and/or power relays.

NOTE: Do not use a soldering iron or desoldering tool of more than 30 watts on

DPC contacts.

(B) With all the terminal pins cleaned and separated from DPC contacts, remove

the defective transformer/power relays and install new transformer/relays

making sure all terminal pins are inserted completely.  Resolder all terminal

contacts carefully.

(A) Disconnect 2 lead wires from fan motor terminals.

(B) Remove 1 screw at located on oven attaching orifice assembly.

(C) Remove orifice assembly/Inverter power supply (U) from oven assembly.

(Refer page 15)

(D) Remove fan blade from the fan motor shaft by pulling it straight out.

(E) Remove 2 screws holding fan motor to orifice.

(F) Separate the fan motor from the orifice assembly by freeing 2 catch hooks on

the orifice assembly.

When replacing the magnetron, be sure the antenna

gasket is in place.

SCREW

- 11 -

(A) Remove door C from door E by carefully pulling outward starting from

upper right hand corner using a flat blade screwdriver.

(B) Separate door E from tabs on door A and remove door A.

(C) Open Door E at the opening angle of approximately 10

°

 (Note:  The door

cannot be removed if the opening angle is greater than 10

°

).

(D) Remove the door from its hinges by pushing the door’s lower hinge pin

upward and out.

(E) Remove door screen B from door A.

(F) Remove door key and door key spring.

(G) When reassembling door hold door E at the opening angle of approximately

10

°

.

(H) Place the door’s lower hinge pin into the bottom hinge hole.

(I) Use your left index finger to support the door’s lower hinge pin while guiding

the door’s upper hinge pin into the top hinge hole.

(J) Lower your finger to seat the door onto the hinges.

(K) Replace other components.

(L)

(A) Remove the motor cover by breaking off at the 8 spots indicated by arrows with

a cutter or the like. (See Figure)

NOTE: After breaking off the motor cover, make sure that cut-off

portions are properly trimmed off or bend to inside so that

no sharp edge will expose to outside.

(B) Disconnect 2 lead wires connected to the turntable motor.

(C) Remove the turntable motor by removing 1 screw.

NOTE: After reinstalling the new turntable motor and reconnecting

the two lead wires, reinstall the motor cover by rotating it around 180  ,

tucking the tabs under the base into the 2 provided slots, then screw the

single tab to the base using a 4mm X 6mm screw (not provided).

DOOR
SCREEN B

DOOR A

DOOR
KEY

DOOR
KEY
SPRING

DOOR E

DOOR C

BASE

MOTOR

COVER

01-046