Sharp Carousel R-980E, Service Manual

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R-980E
17
TEST PROCEDURES
PROCEDURE
LETTER
COMPONENT TEST
2-3 Other possible troubles 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.
d) Proper temperature measurement is not obtained.
If the display fails to clear when the STOP/CLEAR pad is depressed, first verify the flat ribbon cable
is making good contact, 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, disconnect the flat ribbon cable that connects the key
unit to the control unit and make sure the door sensing switch is closed (either close the door or short
the door sensing switch connector). Use the key unit matrix indicated on the control panel schematic
and place a jumper wire between the pins that correspond to the STOP/CLEAR pad making
momentary contact. If the control unit responds by clearing with a beep the key unit is faulty and must
be replaced. If the control unit does not respond, it is 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 key pad is at fault.
N KEY UNIT TEST
O RELAY TEST
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.
P PROCEDURES TO BE TAKEN WHEN THE FOIL PATTERN ON THE PRINTED WIRING BOARD
(PWB) IS OPEN
Remove the outer case and check voltage between Pin No 9 of the 5-pin connector (A) and the
common terminal of the relay RY1 on the control unit with an A.C. voltmeter. The meter should
indicate 230 - 240 volts, if not check oven circuit.
Shut-off, Cook and Heater 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 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. 21.0V D.C. Oven lamp / Turntable motor
RY2(COOK) APPROX. 21.0V D.C. Power transformer
RY3(HEATER) APPROX. 20.0V D.C. Heating element
RY4 APPROX. 21.0V D.C. Damper motor
RY5 APPROX. 21.0V D.C. Convection motor
RY6 APPROX. 21.0V D.C. Cooling fan motor
1
2
3
4
5
6 7
8 9 0
STOP
CLEAR
REHEAT
PIE
EASY
DEFROST
LESS
POWER
LEVEL
40˚C
70˚C
130˚C 150˚C
160˚C
180˚C
200˚C
220˚C 230˚C
250˚C
HIGH MIX
LOW MIX
CONVEC
GRILL
MEMORY
PREHEAT
CLOCK
HELP
REHEAT
SENSOR
MULTI
COOK
FROZEN
VEGETABLES
FRESH
VEGETABLES
DESSERTS
JACKET
POTATO
INSTANT COOK
START
MORE
CASSEROLES
G 1
G 2
G 3
G 4
G 5 G 6 G 7 G 8 G 9 G10 G11 G12