Sharp R-3S68, Service Manual

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R-3S68
12
TEST PROCEDURES (CONT'D)
PROCEDURE
LETTER
COMPONENT TEST
2-2 In connection with indicators
a) At a certain digit, all or some segments do not light up.
b) At a certain digit, brightness is low.
c) Only one indicator does not light.
d) The corresponding segments of all digits do not light up or they continue to light up.
e) Wrong figure appears.
f) A certain group of indicators do not light up.
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) Cooking is not possible.
K TACT SWITCH TEST
If the display fails to clear when the STOP/CLEAR tact switch is depressed, first verify that the door
sensing switch (stop switch) operates properly; that is the contacts are closed when the door is closed
and open when the door is open. If the door sensing switch (stop switch) is good, make sure the door
sensing switch is closed (either close the door or short the door sensing switch connecter). Use the tact
switch matrix indicated on the control panel schematic and place a jumper wire between the pins that
correspond to the STOP/CLEAR tact switch making momentary contact. If the control unit responds by
clearing with a beep, the tact switch is faulty and must be replaced. If the control unit does not respond,
it is a faulty and must be replaced. If a specific pad does not respond, the above method may be used
(after clearing the control unit) to determine if the control unit or tact switch is at fault.
SW1
10
MIN.
AUTO COOK AUTO DEFROST
INSTANT
COOK
START
1
MIN.
10
SEC.
STOP
CLEAR
SW2
SW3
SW4 SW6
SW7
SW5
SW8
POWER
LEVEL
SERVE
L RELAY TEST
CARRY OUT 3D CHECKS.
Remove the outer case and check voltage between Pin Nos. 3 and 5 of the 3 pin connector (A) on the
control unit with an A.C. voltmeter.
The meter should indicate 220 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 or convection 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. 19.0V D.C. Oven lamp / Turntable motor / Cooling fan motor
RY2 APPROX. 18.0V D.C. Power transformer
CARRY OUT 4R CHECKS.