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Check for radiation leakage after every servicing. Should
the leakage be more than 2 mW/cm

2

. After repairing

or replacing any radiation safety device, keep a written
record f o r  future reference,  the leakage reading
must be recorded on the service repair ticket while in
the customer’s home.

*Electromagnatic radiation monitor
*Glass thermometer 212˚F or 100˚C
*600cc glass beaker

Note before measuring.
(1) Do not exceed meter full scale deflection. Leakage monitor

should initially be set to the highest  scale.

(2) To prevent false readings the test probe should be held by the

grip portion of the handle only and moved along the shaded area
in Figure no faster than 1 inch/sec (2.5cm/sec).

(3) Leakage with the outer panel removed ...... less than 5mW/cm

2

 .

(4) Leakage for a fully assembled oven with door normally closed

...... less than 2mW/cm

2

 (1mW/cm

2 

for Canada).

      (5) Leakage for a fully assembled oven [Before the latch switch

(primary) is interrupted] while  pulling the door ...... less than
2mW/cm

2

 .

(A) Pour 275 

± 15cc (9ozs

s

 

± 1/2oz) of 20˚ ± 5˚C (68˚ ± 9˚F) water in a

beaker which is graduated to  600cc, and place in the center of the
oven.

(B) Set the radiation monitor to 2450MHz and use it following the

manufacturer’s recommended test procedure to assure correct
results.

(C) When measuring the leakage, always use the 2 inch (5cm) spacer

supplied with the probe.

(D) Tap the start pad or set the timer and with the magnetron oscillating,

measure the leakage by holding the probe perpendicular to the
surface being measured.

Whenever you replace the magnetron, measure for radiation leakage
before the outer panel is installed and after all necessary components
are replaced or adjusted. Special care should be taken in measur
ing around the magnetron.

After all components, including outer panel are fully assembled,
measure for radiation leakage around the door periphery, the
door viewing window, the exhaust opening and air inlet openings.

After any adjustment or repair to a microwave oven, a leakage read-
ing must be taken. Record this leakage reading on the repair ticket
even if it is zero.
A copy of this repair ticket and the microwave leakage reading should
be kept by repair facility.

Avoid contacting any high voltage parts.

- 21 -

AVOID CONTACTING ANY HIGH VOLTAGE PARTS.

MOVE PROBE ALONG SHADED

AREA(           )AROUND EXHAUST

OPENINGS(as shown)AND AROUND

AIR INLET OPENING

1. DO NOT RE-ADJUST PRESET VOLUME on the H.V.Inverter (U). It is very dangerous to repair or adjust without sufficient

test equipment because this circuit handles very large current with high voltage. Off alignment of inverter board operation
will be dangerous.

2. Ensure proper grounding before checking for trouble.
3. Be careful of the high voltage circuitry, taking necessary precautions when troubleshooting.
4. Discharge high voltage remains in the H.V.Inverter (U).
5. When checking the continuity of the switches or the H.V.Inverter, 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. When
disconnecting a plastic connector from a terminal, you must hold the plastic connector instead of the lead wire and then
disconnect it, otherwise lead wire may be open or the connector cannot be removed.

6. Do not touch any parts of the circuitry on the digital programmer circuit, since static electric discharge may damage this

control panel. Always touch yourself to ground while working on this panel to discharge any static charge in your body.

7. 120V/220V/230V/240V AC is present on the digital programmer circuit (Terminals of power relay’s and primary circuit

of Digital Programmer Circuit). When troubleshooting, be cautious of possible electrical shock hazard.

1.

Oven stops in 3 seconds after pressing start pad

Oven stops in 23 seconds after pressing start pad

Oven stops in 10 seconds after pressing start pad

(Auto sensor cooking)

Oven stops in 60 seconds after pressing start pad

2.

No display and no operation at all.

Fuse is blown.

1. Latch Switch

2. Power relay RY-1

3. Loose lead wire connector CN701, CN702

1. Magnetron

2. Loose lead wire connector CN703

1. Steam sensor

2.DPC

3. Loose wiring connector CN2

1. Oven temp. sensor

2. Loose wiring CN5

1. Allign door, Door Latch Switches

2. Loose wiring connectors

Before troubleshooting, operate the microwave oven following the correct operating procedures in the instruction manual in order to find the exact

cause of any trouble, since operator error may be mistaken for the oven’s malfunction.

No 120/220/230/240V AC is supplied to

H.V.Inverter (U) CN702 terminals

H.V.Inverter (U) operates by the control signals

from DPC but magnetron is not oscillating

Steam sensor circuit is not functions

Oven temperature sensor circuit is not functions

Most probably loose connection of connectors or

door latch mechanizm is not adjusted properly

- 22 -

- 23 -

1.

Oven is dead.

Fuse is OK.

No display and no operation at all.

2.

No display and no operation at all.

Fuse is blown.

3.

Oven does not accept key input(Program)

4.

Oven lamp and fan motor turn on when oven is

plugged in with door closed.

5.

Timer starts count down but no microwave oscil-

lation.

(No heat while oven lamp and fan motor turn on)

6.

Oven can program but timer does not start count-

down.

7.

Microwave output is low. Oven takes longer time

to cook food.

8.

Turntable motor turns on when door is opened.

9.

Loud buzzing noise can be heard.

10.

Turntable motor does not rotate.

11.

Heater does not turn on.

1. Key input is not insequence

2. Open or loose connection of membrane key pad

    to DPC (Flat cable)

3. Shorted or open membrane key board

4. Defective DPC

1. Misadjustment or loose wiring of secondary

    latch switch

2. Defective secondary latch switch

1. Off-alignment of latch switches

2. Open or loose connection of high voltage circuit

    especially magnetron filament circuit

NOTE: Large contact resistance will bring lower

magnetron filament voltage and cause

magnetron to lower output and/or be in-

termittent.

3. Defective high voltage component

    HV Inverter Power Supply (u)

    Magnetron

4. Open or loose wiring of power relay B (RY-1)

5. Defective primary latch switch

6. Defective DPC or power relay B (RY-1)

1. Open or loose wiring of secondary latch switch

2. Off-alignment of secondary latch switch

3. Defective secondary latch switch

1. Decrease in power source voltage

2. Open or loose wiring of magnetron filament

    circuit.(Intermittent oscillation)

3. Aging change of magnetron

1. Shorted primary latch switch

1. Loose fan and fan motor

1. Open or loose wiring of turntable motor

2. Defective turntable motor

1. Defective heater

2. Defective power relay 4 (RY4)

3. Defective DPC

Check fan motor when thermal cutout is defec-

tive.

Check adjustment of primary, secondary latch

switch and short switch including door.

Refer to inverter PCB Troubleshooting

Refer to operation procedure.

Refer to DPC troubleshooting.

Adjust door and latch switches.

Adjust door and latch switches.

Check high voltage component according to

component test procedure and replace if it is

defective.

Refer to DPC troubleshooting.

Adjust door and latch switches.

Consult electrician

1. Open or loose lead wire harness

2. Open thermal cutout (Cavity)

3. Defective DPC

1. Shorted lead wire harness

2. Defective primary latch switdh (NOTE 1)

3. Defective short switch (NOTE 1)

4. Defective Inverter Power Supply (U)

    Refer to component test procedure

NOTE 1: All of these switches must be replaced at the same time.

Check continuity of power relay (RY1)’s contacts (between 1 and 2) and if it has continuity,

replace power relay B (RY-1) also.

- 24 -

No display when oven is first plugged in

No key input

No beep sound

Power relay A (RY-2) does not turn on even

though the program has been set and the

start pad is tapped

No microwave oscillation at any power

setting

Dark or unclear display

Missing or lighting of unnecessary segment

Normal

Open

Abnormal

Normal = 5V

Abnormal

Normal

Abnormal

Normal

Abnormal

Normal = 5V

Still not turn on

Ry-2 turns on

Abnormal

Normal

5--- = 5v

Abnormal

Normal

Normal

Abnormal

Normal

Abnormal

Fuse resistor R28 1

Ω

Q10 emitter

(Output terminal)

Membrane switch continuity

IC-1 pin 8 voltage

IC-1 pin 41 voltage while operation

Short circuit between pin 8 and pin

12 of IC-220

IC-1 pin 9 voltages while operation at

high power

Q220 transistor

Replace display and check operation

Replace IC-1 and check operation

STEP 2

Shorted circuit of IC-10

Q10
➝ IC-1, CX320, DISPLAY
Membrane switch

IC-1

IC-1

BZ, IC-220

IC-1
➝ Step 2
RY-2

IC-220

IC-1
➝ Step 2

Q220

IC-220, RY-1

DISPLAY

IC-1

IC-1

DISPLAY

1

2

1

1

1

2

1

2

1

1

Inverter PCB Repair Procedures

1. Unplug oven when removing outer cabinet.
2. never touch inverter PCB with oven plugged in inverter PCB handling over 7,000V and it is very danger!
3. Heat sink is also energized with High Voltages!
4. Discharge high voltage before touching circuitry.
5. When testing inverter PCB, completely install it into oven, put outer cabinet and make ground.

1. Unplug oven and leave it for more than 30 seconds before
    removing outer cabinet.
2. Use insulated lead wire to short across D701 Anode to D702
    Cathode or short across magnetron filament terminals to the
    chassis ground. Please refer to service manual for detail of the
    specified model.

Refer tp related service manual for inverter PCB removal.

1. Visual check:
    a. PCB board: Any crack on board, burnt printed copper foil
        pattern? Any cockroach, bugs excrements, any mark of wet?
    B. Components: Any damaged components? Any burnt, broken or
        missing?