R-27STM
11
L: SWITCH UNIT TEST
CARRY OUT
1.
3D
CHECKS.
Isolate the switch unit with the control panel frame to be tested.
2.
Using an ohmmeter and referring to the switch unit matrix indicated on the switch unit circuit, check the circuit between the pins of
3.
the switch unit that correspond to the STOP button. When the button is pressed, the ohmmeter should indicate short circuit. When
the button is released, the ohmmeter should indicate open circuit. If incorrect readings are obtained, the switch unit button is faulty
and must be replaced. About the other buttons, the above method may be used.
CARRY OUT
4.
4R
CHECKS.
A-3
A-4
A-5
A-6
B-2
B-3
A-1
A
B
C
SW100
A-2
C100
C101
R100
R101
A-7
B-1
C-1
C-2
C-3
3PIN
WIRE
HARNESS
SWITCH UNIT
EXPRESS
COOK
MEAT
JOINT
TIME
WEIGHT
MINCED
MEAT
WHOLE
POULTRY
POWER
LEVEL
STOP
CLEAR
START
AUTO
MINUTE
SW1
SW2
SW3
SW4
SW5
SW6
SW7
M: RELAY TEST
CARRY OUT
3D
CHECKS.
Remove the outer case and check voltage between the upper side terminal of the relay RY1 and the oven side terminal of the relay
RY2 on the control unit with an A.C. voltmeter. The meter should indicate 230 - 240 volts, if not check oven circuit.
RY1 and RY2 Relay Test
These relays are operated by D.C. voltage
Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking operation.
DC. voltage indicated .................. Defective relay.
DC. voltage not indicated ............
Check diode which is connected to the relay coil. If diode is good, control unit is defective.
RELAY SYMBOL
OPERATIONAL VOLTAGE
CONNECTED COMPONENTS
RY1
Approx. 12.6V D.C.
Oven lamp / Turntable motor / Cooling fan motor
RY2
Approx. 12.1V D.C.
High voltage transformer
CARRY OUT
4R
CHECKS.
N: PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD (PWB)
IS OPEN
To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the PWB, this foil pattern acts
as a fuse. If the foil pattern is open, follow the troubleshooting guide given below for repair.
Problem: POWER ON, indicator does not light up.
CARRY OUT
3D
CHECKS.
STEPS
OCCURRENCE
CAUSE OR CORRECTION
1
The rated AC voltage is not present between the upper side terminal of
the relay RY1 and the oven side terminal of the relay RY2.
Check supply voltage and oven power cord.
2
The rated AC voltage is present to primary side of low voltage transformer.
Low voltage transformer or secondary circuit defective.
Check and repair.
3
Only pattern at "a" is broken.
*Insert jumper wire J1 and solder.
4
Pattern at "a" and "b" are broken.
*Insert the coil RCILF2003YAZZ between "c" and "d".
NOTE: *At the time of making these repairs, make a visual inspection of the varistor. Check for burned damage and examine
the transformer with a tester for the presence of layer short-circuit (check the primary coil resistance). If any abnor-
mal condition is detected, replace the defective parts.
CARRY OUT
4R
CHECKS.
R27STM.indd 11
11/3/08 2:04:27 PM
