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AX-1110(SL)M

9 – 1

AX1100(R)

CARRY OUT 3D CHECKS.

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

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 IEC test procedure, i.e. it can be measured by using water load how much it can be absorbed by the water
load. 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(sec-
ond), 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.

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 of 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 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) 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 100% 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.

CAUTION: 1 C CORRESPONDS TO 90 WATTS. REPEAT MEASUREMENT IF THE POWER IS INSUFFICIENT.

   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 ........................... VoltageRated voltage
          Water load .........................................................1000 g                          Initial temperature (T1) .................................... 10±1°C
          Heating time ..................................................... 47 sec.                          Mass of container (mc) ...................................... 330 g
          T2 .................................................... Final Temperature                T = T2 - T1                 P = 90 x  T + 0.55 x mc (T2-T0)/47

          Room temperature ................................................................... To = 21 C
          Initial temperature ..................................................................... T1 = 11 C
          Temperature after (47 + 3) = 50 sec. ...................................... T2 = 21 C
          Temperature difference Cold-Warm ( T = T2 - T1)  ..........  T = 10 C
          Measured output power
          The equation is "P = 90 x  T" .................... P = 90 x 10 C = 900 Watts

AX-1110(SL)M

9 – 2

1. CARRY OUT 3D CHECKS.

2. 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 winding. The following readings
should be obtained:

                  a.Primary winding -------------------- approximately 1.98 

                  b.Secondary winding --------------- approximately 159.5   

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

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

3. 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  in the other direction.

CARRY OUT 4R CHECKS.

ASYMMETRIC RECTIFIER TEST

CARRY OUT 3D CHECKS.

Isolate the high voltage rectifier assembly from the HV circuit. The asymmetric rectifier can be
tested using an ohmmeter set to its highest range across the terminals A+B of the asymmetric
rectifier and note the reading obtained. Reverse the meter leads and note this second reading.
If an open circuit is indicated in both directions then the asymmetric rectifier is good. If the
asymmetric rectifier is shorted in either direction, then the asymmetric rectifier is faulty and must be replaced with high voltage rectifier. When the
asymmetric rectifier is defective, check whether magnetron, high voltage rectifier, high voltage wire or filament winding of the high voltage transformer
is shorted.

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.

1. Isolate the high voltage capacitor from the circuit.

2. Continuity check must be carried out with measuring instrument which is set to the highest resistance range.

3. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10M  after it has been charged.

4. A short-circuited capacitor shows continuity all the time.

5. An open capacitor constantly shows a resistance about 10 M  because of its internal 10M  resistance.

6. When the internal wire is opened in the high voltage capacitor shows an infinite resistance.

7. 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.

WARNING: High voltages and large currents are present at the secondary winding and filament winding of the power transformer. It is 

1000g

1000g

1000g

Heat up for 50 sec.

D2

D1

ASYMMETRIC
RECTIFIER

HIGH VOLTAGE
RECTIFIER

AX-1110(SL)M

9 – 3

CARRY OUT 3D CHECKS.

Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following table.

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

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Before performing this test, make sure that the monitored interlock switch and the relay RY-4 on the control unit are operating properly, according to
the above Switch Test Procedure. Disconnect the wire lead from the monitor switch (COM) terminal. Check the monitor switch operation by using the
ohmmeter as follows. When the door is open, the meter should indicate a closed circuit. When the monitor switch actuator is pushed by a screw driver
through the right latch hole on the front plate of the oven cavity with the door opened (in this condition the plunger of the monitor switch is pushed in),
the meter should indicate an open circuit. If improper operation is indicated, the switch may be defective. After testing the monitor switch, reconnect
the wire lead to the monitor switch (COM) terminal and check the continuity of the monitor circuit.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Disconnect the thermistor from the control unit. Measure the resistance of the thermistor with an ohmmeter.

If the meter does not indicate above resistance, replace the thermistor.

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 test across the two terminals as described
in the below.

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

An open circuit thermal cut-out (MG) TC1 indicates that the magnetron has overheated, this may be due to resistricted ventilation, cooling fan failure.

An open circuit thermal cut-out (OVEN) TC2 indicates that the oven cavity has overheated, this may be due to no load operation or fire in the oven
cavity.

An open circuit thermal cut-out (Engine) TC3 indicates that the engine unit has overheated, this may be due to empty water tank or pump motor fail-
ure.

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

If the fuse F1 20A is blown, there is a shorts or grounds in electrical parts or wire harness. Check them and replace the defective parts or repair the
wire harness.

CARRY OUT 4R CHECKS.

CAUTION: Only replace fuse with the correct value replacement.

Table: Terminal Connection of Switch

Plunger Operation

Common terminal to Normally open terminal

Common terminal to Normally close terminal

c

ri

c

 

n

e

p

O

d

e

s

a

e

l

e

R

 t

i

u

c

ri

c

 t

r

o

h

S

ti

u

.t

i

u

c

ri

c

 

n

e

p

O

 t

i

u

c

ri

c

 t

r

o

h

S

d

e

s

s

e

r

p

e

D

Room Temperature

25 C

100 C

200 C

Resistance

Approximately 200 k

Approximately 10 k

Approximately 1 k

Table: Thermal Cut-out Test

Parts Name

Temperature of “ON” condition 

(closed circuit)

Temperature of “OFF” condition 

(open circuit)

Indication of ohmmeter (When room 
temperature is approx. 20 C.)

Thermal cut-out TC1 145 C

Bellow -20

5

4

1

 

e

v

o

b

A

C

ti

u

c

ri

c

 

d

e

s

o

l

C

C

Thermal cut-out TC2, TC3

Bellow -20 or -35 C.

Above 170

ti

u

c

ri

c

 

d

e

s

o

l

C

C

AX-1110(SL)M

9 – 4

CARRY OUT 3D CHECKS.

1. If the fuse F2 F8A is blown when the door is opened, check the monitored interlock switch and monitor switch.

2. If the fuse F2 F8A is blown by incorrect door switching replace the defective switch(es) and the fuse F2 F8A.

3. If the fuse F2 F8A is blown, there could be shorts in the asymmetric rectifier or there is a ground in wire harness. A short in the asymmetric rectifier

may be occurred due to short or ground in H.V. rectifier, magnetron, high voltage transformer or H.V. wire. 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 the noise filter. Using an ohmmeter, check
between the terminals as described in the following table. 

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

CARRY OUT 4R CHECKS.

CARRY OUT 3D CHECKS.

Before carrying out the following tests make sure the heating element is cool completely. 

1. Resistance of heater.

Disconnect the wire leads to the heating element to be tested. Using ohmmeter with low resistance range. Check the resistance across the termi-
nals of the heating element as described in the following table.

2. Insulation resistance.

Disconnect the wire leads to the heating element to be tested. Check the insulation resistance between the element terminal and cavity using a
500V - 100M  insulation tester. The insulation resistance should be more than 10M  in the cold start.

If the results of above test 1 and/or 2 are out of above specifications, the heating element is probably faulty and should be replaced.

CARRY OUT 4R CHECKS.

The control unit consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper mainte-
nance can not be performed with only a voltmeter and ohmmeter.

In this service manual, the control panel assembly is divided into two units, Control Unit and Key Unit, and troubleshooting by replacement is
described according to the symptoms indicated.

The following symptoms indicate a defective key unit. Replace the key unit.

1) When touching the pads, a certain pad produces no signal at all.

2) When touching a number pad, two figures or more are displayed.

3) When touching the pads, sometimes a pad produces no signal.

The following symptoms indicate a defective control unit. Before replacing the control unit perform the key unit test (Procedure N) to determine if con-
trol unit is faulty.

1) When touching the pads, a certain group of pads do not produce a signal.

2) When touching the pads, no pads produce a signal.

MEASURING POINT 

INDICATION OF OHMMETER

Between N and L 

Approx. 680 k

Between terminal N and WHITE 

Short circuit

Between terminal L and RED 

Short circuit

Table: Resistance of heater

e

c

n

a

t

s

i

s

e

R

e

m

a

n

 

s

t

r

a

P

Grill heating element

Approximately 46.5 ~ 51.1

Engine heating element

Approximately 58.0 ~ 62.9

F2: F8A

20A

WHT

RED

R1

R2

N

Cx

Cy

L

L

L

L (min) Cx ± 20%

Cy ± 20%

R1

R2

1.0mH

0.22 uF

4700pF

10 M

680k