Sharp R-312AW Service Manual page 15

PROCEDURE
LETTER
c) Cooking is not possible.
Note: When defective components, the Power Unit or Key Unit are replaced, the defective part or parts
must be properly packed for return in the shipping carton, with its cushion material, in which the
new replacement part was shipped to you.
K KEY UNIT TEST
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
connecter). 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 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 key pad is at fault.
L RELAY TEST
Remove the outer case and check voltage between Pin No. 3 of the 2 pin connector (A) and the common
terminal of the relay RY2 on the control unit with an A.C. voltmeter.
The meter should indicate 120 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
RELAY SYMBOL
M COMPU DEFROST TEST
(1) Place one cup of water in the center of the turntable tray in the oven cavity.
(2) Close the door, touch the " COMPU DEFROST " pad twice and touch the Number pad " 5 ". And
then touch the "START" pad.
(3) The oven is in Compu Defrost cooking condition.
(4) The oven will operate as follows
WEIGHT
0.5lbs
(5) If improper operation is indicated, the control unit is probably defective and should be checked.
TEST PROCEDURES
G 8 G 7
5
4
0 9
START
COMPU
MINUTE
DEFROST VEGETABLE
PLUS
TIMER
POWER
LEVEL CLOCK
unit is defective.
OPERATIONAL VOLTAGE
RY1 Approx. 14.0 D.C.
RY2 Approx. 12.8 D.C.
1ST STAGE 2ND STAGE
LEVEL TIME LEVEL
70% 40sec. 50%
COMPONENT TEST
G 6 G 5 G 4 G 3
2 1
3
8 7 6
POPCORN
FRESH REHEAT DINNER
BEVERAGE
CASSEROLE PLATE
FROZEN FRESH
STOP
BAKED
ROLL ROLL
POTATO CLEAR
/ MUFFIN
/ MUFFIN
Oven lamp / Turntable motor / Cooling fan motor
Power transformer
3RD STAGE
TIME LEVEL TIME
38sec. 30% 43sec.
13
G 2 G 1
CONNECTED COMPONENTS
R-312AW
R-312AK