Read Sharp R-249 Service Manual online
R-249(SL)
R-249(W)
R-249(W)
11
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
f) A certain group of indicators do not light up.
g) The figure of all digits flicker.
g) The figure of all digits flicker.
2-3 Other possible problems caused by defective control unit.
a) Buzzer does not sound or continues to sound.
b) Clock does not operate properly.
c) Cooking is not possible.
b) Clock does not operate properly.
c) Cooking is not possible.
L
KEY UNIT TEST
1. CARRY OUT 3D CHECKS.
2. Isolate the key unit with the control panel frame to be tested.
3. Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check
2. Isolate the key unit with the control panel frame to be tested.
3. Using an ohmmeter and referring to the key unit matrix indicated on the control unit circuit, check
the circuit between the pins of the key unit that correspond to the STOP/CLEAR pad. When the
pad is pressed, the ohmmeter should indicate short circuit. When the pad is released, the
ohmmeter should indicate open circuit. If incorrect readings are obtained, the key unit is faulty and
must be replaced. About the other pads, the above method may be used.
pad is pressed, the ohmmeter should indicate short circuit. When the pad is released, the
ohmmeter should indicate open circuit. If incorrect readings are obtained, the key unit is faulty and
must be replaced. About the other pads, the above method may be used.
4. CARRY OUT 4R CHECKS.
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin No. 3 of the 2 pin connector (A) and normal
open 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.
Remove the outer case and check voltage between Pin No. 3 of the 2 pin connector (A) and normal
open 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.
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,
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. 14.0V D.C.
Oven lamp / Turntable motor / Cooling fan motor
RY2
Approx. 13.0V D.C.
High voltage transformer
CARRY OUT 4R CHECKS.
M
RELAY TEST
G4
G5
G6
G1
G8
G9
G10
G2
G3
G7
10sec
1min.
10min.
Express
COOK
START
AUTO
MINUTE
Express
DEFROST
STOP
CLEAR
POWER
WEIGHT
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.
on the PWB, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide
given below for repair.
Pin
NO. G1
NO. G1
Pin
NO. G10
NO. G10
Key unit ribbon cable
Key unit (Membrane Switch) front view
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