Sharp R820bk Service Manual

9
R-820BK
R-820BW
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. MICROWAVE POWER LEVEL PAD PRESSED ONCE(100%).
3. COOKING TIME PROGRAMMED.
4. START PAD TOUCHED.
Figure O-2 Oven Schematic-Microwave cooking Condition
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2.        :              OR CLOCK APPEAR ON DISPLAY.NOTE: Indicates components with potential above 250 V.
Figure O-1 Oven Schematic-OFF Condition
FMTTMOVEN LAMPFAN MOTOR
TURNTABLE 
MOTOR
H.V. RECTIFIER
CONTROL UNIT
RPIMARY
INTERLOCK...

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R-820BK
R-820BW
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. GRILL PAD TOUCHED.
3. NUMBER 2 PAD TOUCHED.
4. COOKING TIME PROGRAMMED.
5. START PAD TOUCHED.SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. GRILL PAD TOUCHED.
3. NUMBER 1 PAD TOUCHED.
4. COOKING TIME PROGRAMMED.
5. START PAD TOUCHED.
Figure O-3a Oven Schematic-Grill cooking Condition (TOP AND BOTTOM HEATER mode)
NOTE: Indicates components with potential above 250 V.
Figure O-3b Oven Schematic-Grill cooking Condition (TOP HEATER...

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R-820BK
R-820BW
Figure O-5 Oven Schematic-Roast cooking Condition Figure O-4 Oven Schematic-Convection cooking Condition (Convection with preheat mode)
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. CONVECTION PAD TOUCHED.
3. NUMBER 1 PAD TOUCHED.
4. TEMPERATURE PAD TOUCHED.
5. COOKING TIME PROGRAMMED.
6. START PAD TOUCHED.
SCHEMATIC
NOTE: CONDITION OF OVEN
1. DOOR CLOSED.
2. ROAST PAD TOUCHED.
3. COOKING TIME PROGRAMMED.
4. START PAD TOUCHED.
FMTTMOVEN LAMPFAN MOTOR
TURNTABLE 
MOTOR
H.V....

12
R-820BK
R-820BW
DESCRIPTION AND FUNCTION OF COMPONENTS
DOOR OPEN MECHANISM
The door is opened by pushing the open button on the
control panel, refer to Figure D-1.
When the open button is pushed, the open button pushes up
the switch lever, and then the switch lever pushes up the
latch head. The latch heads are moved upward and re-
leased from latch hook. Now the door will open.of the monitor switch contacts.
CAUTION: BEFORE REPLACING A BLOWN MONITOR
FUSE TEST THE DOOR SENSING SWITCH,
PRIMARY INTERLOCK...

13
R-820BK
R-820BW
TROUBLESHOOTING GUIDE
Never touch any part in the circuit with your hand or an uninsulated tool while the power supply is connected.
When troubleshooting the microwave oven, it is helpful to follow the Sequence of Operation in performing the checks. Many
of the possible causes of trouble will require that a specific test be performed. These tests are given a procedure letter which
will be found in the Test Procedure section.
IMPORTANT:If the oven becomes inoperative because of a blown...

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R-820BK
R-820BW
CK = Check / RE = Replace
ABCDE E F FGH I I J LMNNNNNNOPRE RE RE RE RECK CK CKTEST PROCEDURE
MAGNETRON
POWER TRANSFORMER
H.V. RECTIFIER ASSEMBLY
HIGH VOLTAGE CAPACITOR
THERMAL CUT-OUT 170˚C
THERMAL CUT-OUT 125˚CSECONDARY INTERLOCK SWITCHPRIMARY INTERLOCK SYSTEM
MONITOR SWITCH
MONITOR FUSE
TOP HEATERS
BOTTOM HEATER
THERMISTOR
TOUCH CONTROL PANEL
KEY UNIT
RELAY RY1
RELAY RY2
RELAY RY3
RELAY RY4
RELAY RY5
RELAY RY6
COMPU DEFROST
FOIL PATTURN ON P.W.B.
FAN MOTOR CONVECTION MOTOR
TURNTABLE...

15
R-820BK
R-820BW
BPOWER TRANSFORMER TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the primary input terminals and measure the resistance of the transformer with an
ohmmeter. Check for continuity of the coils with an ohmmeter. On the R x 1 scale, the resistance of
the primary coil should be less than 1 ohm and the resistance of the high voltage coil should be
approximately 73 ohms; the...

16
R-820BK
R-820BW
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. If the capacitor is open, no high voltage will be available to the magnetron. Disconnect input leads
and check for a short or open between the terminals using an ohmmeter.
Checking with a high ohm scale, if the high voltage capacitor is normal, the meter will indicate
continuity for a short time and...

17
R-820BK
R-820BW
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. Before performing this test, make sure that the secondary interlock switch and the primary interlock
relay are operating properly, according to the above Switch Test Procedure. Disconnect the wire lead
from the monitor switch (COM) terminal. Check the monitor switch operation by using the ohmmeter
as...

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R-820BK
R-820BW
HBLOWN MONITOR FUSE TEST
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
1. Disconnect the power supply cord, and then remove outer case.
2. Open the door and block it open.
3. Discharge high voltage capacitor.
4. If the monitor fuse is blown when the door is opened, check the primary interlock relay, secondary
interlock switch and monitor switch according to the TEST PROCEDURE for those switches before
replacing the blown monitor fuse.
CAUTION: BEFORE REPLACING A BLOWN MONITOR FUSE,...