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7

NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL
WHILE THE OVEN IS IN OPERATION.

CARRY OUT 3D CHECK.

Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal.

To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron
filament terminals, the meter should show a reading of less than 1 ohm.

To test for short circuit filament to anode condition, connect ohmmeter between one of the filament
terminals and the case of the magnetron (ground). This test should be indicated an infinite resistance.
If a low or zero resistance reading is obtained then the magnetron should be replaced.

MICROWAVE OUTPUT POWER TEST
The power output of this oven is rated using the method specified by  IEC 60705.

The IEC60705 procedure must be carried out using laboratory-type procedures and equipment.
These requirements make the procedure unsuitable for routine performance checks.

NOTE: The following test method gives an indication of the output power only, it cannot be used to

establish the actual/rated output power. If the true output power is required, then the IEC60705
test method must be used.

Alternative simplified method:
1. Place 2  litres of cold water (between 12

°

C and 20

°

C) in a suitable container.

2. Stir the water and measure the temperature in 

°

C. Note temperature as T1.

3. Place the container in the microwave and heat the water for 1 minute and 27 seconds on full power.

4. When the 1 minute and 27 seconds is completed, remove the  container and stir the water. Note

the water temperature as T2.

5. Calculate the output power using the following formula:

R.F. Power Output = (T2 - T1) x 100.

±

MICROWAVE LEAKAGE TEST
This oven should be tested for microwave leakage on completion of any repair or adjustment. The
maximum leakage permitted in BS EN 60335-2-25 is 50W/m

2 

(equivalent to 5W/m

2

), however it is not

normal to detect any significant leakage, therefore, any leakage which is detected should be
investigated.

It is essential that only leakage detectors with current calibration traceable to National Physical
Laboratories are used.

Suitable leakage detectors: CELTEC A100

APOLLO X1

MICROWAVE OUTPUT POWER (1 litre load, IEC60705 procedure)
The following test procedure should be carried out with the microwave oven in a fully assembled
condition (outer case fitted). Microwave output power from the magnetron can be measured by way
of IEC 60705, i.e. it is measured by how much power the water load can absorb. To measure the
microwave output power in the microwave oven, the relation of calorie and watt is used. When P(W)
heating works for t(second), approximately P x t/4.187 calorie is generated. On the other hand, if the
temperature of the water with V(ml) rises 

∆

T (

°

C) during this microwave heating period, the calorie of

the water is V x 

∆

T.

The formula is as follows;

P x t / 4.187 = V x 

∆

 T+ 0.55 x mc (T2-T0)/4.187

P (W) = 4.187 x V x 

∆

T / t + 0.55 x mc (T2-T0)/t

Our condition for water load is as follows:

Room temperature (T0) ... around 20

°

C

Power supply Voltage .............. Rated voltage

Water load .................................. 1000 g

Initial temperature (T1) ...................... 10

±

1

°

C

Heating time .............................. 42 sec.

Mass of container (mc) ......................... 330 g

T2 ............................ Final Temperature

P = 100 x 

∆

T + 0.55 x mc (T2-T0)/42

8

Measuring condition:
1. Container

The water container must be a cylindrical borosilicate glass vessel having a maximum material
thickness of 3 mm and an outside diameter of approximately 190 mm.

2. Temperature of the oven and vessel

The oven and the empty vessel are at ambient temperature prior to the start the test.

3. Temperature of the water

The initial temperature of the water is (10

±

1)

°

C.

4. Select the initial and final water temperature so that the maximum difference between the final water

temperature and the ambient temperature is 5

°

C.

5. Select stirring devices and measuring instruments in order to minimize addition or removal of heat.
6. The graduation of the thermometer must be scaled by 0.1

°

C at minimum and be an accurate

thermometer.

7. The water load must be (1000

±

5) g.

8. “t” is measured while the microwave generator is operating at full power. Magnetron filament heat-

up time is not included.

NOTE: The operation time of the microwave oven is “t + 3” sec. (3 sec. is magnetron filament heat-up time.)

Measuring method:
1. Measure the initial temperature of the water before the water is added to the vessel.

(Example: The initial temperature T1 = 11

°

C)

2. Add the 1 litre water to the vessel.
3. Place the load on the centre of the shelf.
4. Operate the microwave oven at HIGH for the temperature of the water rises by a value 

∆

 T of

10˚C.

5. Stir the water to equalize temperature throughout the vessel.
6. Measure the final water temperature. (Example: The final temperature T2 = 21

°

C)

7. Calculate the microwave power output P in watts from above formula.

Room temperature ....................... To = 21˚C

Initial temperature ....................  T1 = 11

°

C

Temperature after (42 + 3) = 45 sec. .....................................................................  T2 = 21

°

C

Temperature difference Cold-Warm ....................................................................  

∆

T1 = 10

°

C

Measured output power
The equation is “P = 100 x 

∆

T” ................................................ P = 100 x 10

°

C = 1000 Watts

±

CAUTION: 1

°

C CORRESPONDS TO 100 WATTS. REPEAT MEASUREMENT IF THE POWER IS

INSUFFICIENT.

Heat up for 45 sec

1000g

1000g

1000g

9

Table: Terminal Connection of Switch

Plunger Operation

COM to NO

COM to NC

Released

Open circuit

Short circuit

Depressed

Short circuit

Open circuit

COM; Common terminal,
NO;

Normally open terminal

NC;

Normally close terminal

If incorrect readings are obtained, make the necessary switch adjustment or replace the switch.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.
Isolate the switch to be tested and using an ohmmeter check between the terminals as described in
the following table.

CARRY OUT 3D CHECKS.
Disconnect the leads to the primary winding of the high voltage  transformer. Disconnect the filament
and secondary winding connections from the rest of the HV circuitry. Using an ohmmeter, set on a low
range,  it is possible to check the continuity of all three windings. The following readings should be
obtained:-

a. Primary winding ................................ approximately 1.3 

Ω

b. Secondary winding ............................ approximately 86 

Ω

c. Filament winding .........................................  less than 1 

Ω

If the readings obtained are not stated as above, then the high voltage transformer is probably faulty
and should be replaced.
CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier  can be tested
using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal B+C of the high
voltage rectifier and note the reading obtained. Reverse the meter leads and note this second reading.
The normal resistance is infinite in one direction and more than 100 k

Ω

 in the other direction.

CARRY OUT 4R CHECKS.

NOTE: FOR MEASUREMENT OF THE RESISTANCE OF THE RECTIFIER, THE BATTERIES OF

THE MEASURING INSTRUMENT MUST HAVE A VOLTAGE AT LEAST 6 VOLTS, BECAUSE
OTHERWISE AN INFINITE RESISTANCE MIGHT BE SHOWN IN BOTH DIRECTIONS.

CARRY OUT 3D CHECKS.

A. Isolate the high voltage capacitor from the circuit.
B. Continuity check must be carried out with measuring instrument which is set to the highest

resistance range.

C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10M

Ω

 after

it has been charged.

D. A short-circuited capacitor shows continuity all the time.
E. An open capacitor constantly shows a resistance about 10 M

Ω

 because of its internal 10M

Ω

resistance.

F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.
G. The resistance across all the terminals and the chassis must be infinite when the capacitor is  normal.
If incorrect reading are obtained, the high voltage capacitor must be replaced.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Disconnect the leads from the terminals of the thermal cut-out. Then using an ohmmeter, make a continuity

10

test across the two terminals as described in the below.

Table: Thermal Cut-out Test

Temperature of "ON"

Temperature of "OFF"

Indication of ohmmeter

Parts Name

 condition  (closed circuit).

condition (open circuit).

(When room temperature

(˚C)

(˚C)

is approx. 20˚C.)

Thermal cut-out 125˚C

This is not resetable type.

Above 125˚C

Closed circuit

Thermal cut-out 145˚C

This is not resetable type.

Above 145˚C

Closed circuit

If incorrect readings are obtained, replace the thermal cut-out.

An open circuit thermal cut-out (MG) indicates that the magnetron has overheated, this may be due to
resistricted ventilation, cooling fan failure or a fault condition within the magnetron or HV. circuit.

An open circuit thermal cut-out (OVEN) indicates that the food in the oven cavity may catch fire, this may
be due to over heating produced by improper setting of the cooking timer or failure of the control panel.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

If the fuse M10A is blown when the door is opened, check the 1st. interlock switch, monitor switch and
monitor resistor.

If the fuse M10A is blown, there could be a short or ground in electrical parts or wire harness. Check
them and replace the defective parts or repair the wire harness.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.
Disconnect the leads from the terminals of noise filter.
Using an ohmmeter, check between the terminals as described
in the following table.

Between N and L

Approx. 680 k

Ω

Between terminal N and WHITE

Short circuit

Between terminal L and RED

Short circuit

If incorrect readings are absorbed, replace the noise filter unit.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two
terminals as described in the table below.

Table: Resistance of Motor

Motors

Resistance

Fan motor

Approximately 219 

Ω

Antenna motor

Approximately 11 k

Ω

If incorrect readings are obtained, replace the motor.

CARRY OUT 4R CHECKS.

FUSE
M10A

N

L

DISCHARGE RESISTOR 680 k

Ω

NOISE SUPPRESSION COIL 

NOISE FILTER

LINE BYPASS
CAPACITOR
0.0033

µ

F/ AC 250V

DISCHARGE
RESISTOR 10M

Ω

LINE BYPASS
CAPACITOR
0.0033

µ

F/ AC 250V

LINE CROSS CAPACITOR 0.068

µ

F/ AC 250V

CARRY OUT 3D CHECKS.