Sharp R820bk Service Manual

29
R-820BK
R-820BW
1. Precautions for Handling Electronic Components
This unit uses CMOS LSI in the integral part of the circuits.
When handling these parts, the following precautions should
be strictly followed. CMOS LSI have extremely high
impedance at its input and output terminals. For this reason,
it is easily influenced by the surrounding high voltage power
source, static electricity charge in clothes, etc., and
sometimes it is not fully protected by the built-in protection
circuit.
In order to...

30
R-820BK
R-820BW
To remove the outer case, proceed as follows.
1. Disconnect the power supply cord.
2. Open the oven door and block it open.
3. Remove the two (2) screws (LHSTIX screws) holding the
back plate to the oven cavity rear plate, by using LHSTIX
screw driver (LHSTIX LR-4).
4. Remove the back plate with the sub back plate.5. Remove the two (2) screws from the lower portion of the
rear cabinet using a T20H Torx type or GTXH20-100
screw driver.
6. Remove the remaining three (3) screws from rear...

31
R-820BK
R-820BW
POWER TRANSFORMER REMOVAL
6. Disconnect the main wire harness from the power
transformer.
7. Remove the two (2) screws  holding the transformer to
base plate.
8. Remove the transformer.
9. Now the power transformer is free. 1. Disconnect the power supply cord and then remove
outer case.
2. Open the oven door and block it open.
3. Discharge high voltage capacitor.
4. Disconnect the filament leads of power transformer from
high voltage capacitor and the magnetron.
5. Disconnect the H.V....

32
R-820BK
R-820BW
POSITIVE LOCK¨  CONNECTOR (NO-CASE TYPE) REMOVAL
Figure C-2.  Positive lock¨ connector 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. Push the lever of positive lock
¨ connector.
5. Pull down on the positive lock¨ connector.
CAUTION: WHEN CONNECTING THE POSITIVE LOCK
¨
CONNECTORS TO THE TERMINALS, IN-
STALL THE POSITIVE LOCK¨ SO THAT THE
LEVER FACES YOU
Oven lamp
socket
Terminal
Wire lead...

33
R-820BK
R-820BW
COOLING FAN MOTOR REMOVAL
REMOVAL
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 wire leads from the fan motor.
5. Remove the one (1) screw  holding the capacitor holder
to the oven cavity rear plate.
6. Remove the one (1) screw holding the fan duct to the
oven cavity rear plate.
7. Release the tabs of the capacitor holder from fan duct.
8. Remove the fan duct from the oven.
9....

34
R-820BK
R-820BW
DOOR SENSING SWITCH/SECONDARY INTERLOCK SWITCH AND MONITOR SWITCH REMOVAL
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. Now, the back plate with the sub back plate should be
removed.
5. Disconnect the connector CN-D from the control unit.
6. Remove the one  (1) screw holding the air duct to the
oven cavity rear plate.7. Remove the air duct with the air guide cover and the
partition plate from...

35
R-820BK
R-820BW
REMOVAL
1. Disconnect the power supply cord.
2. Push the open button and open the door slightly.
3. Insert a putty knife (thickness of about 0.5mm) into the
gap between the choke cover and door frame as shown
in Figure C-6 to free engaging parts.
4. Pry the principles of the lever and lift up the choke cover
by inserting a putty knife as shown in Figure C-6.
5. Release choke cover  from door panel.
6. Now choke cover is free.
DOOR REPLACEMENT
DOOR SENSING SWITCH/SECONDARY INTERLOCK...

36
R-820BK
R-820BW
7. Release two (2) pins of door panel from two (2) holes of
upper and lower oven hinges by lifting up.
8. Now, door sub assembly is free from oven cavity.
9. Remove the four (4) screws holding the door panel to the
door frame.
10.Release door panel from seven (7) tabs of door frame by
sliding door panel downward.
11.Now, door panel is free.
12.Slide latch head upward and remove it from door frame
with releasing latch spring from door frame and latch
head.
13.Now, latch head and latch...

38
R-820BK
R-820BW
6
45
12
3
6
45
12
3 A
B
C
D
E
F
G
HA
B
C
D
E
F
G
H
Figure S-2. Power Unit Circuit
+
–
+
–+
–
COM
N.O.
COM
N.O.
COM
N.O.
COM
N.O.
A 3
OVEN LAMP
TURNTABLE
MOTOR

BOTTOM
HEATER
TOP
HEATER
MICRO
DOOR SWITCH
OVEN THERMISTOR AC120V
60HzLED
GND
VC
VA
VR
INT
BUZZER
FAN MOTOR
CONVECTION
MOTOR
N.C.
OVEN
THERMISTOR
N.C. MICRO OVEN LAMP
TURNTABLE
MOTOR
BOTTOM
HEATER
TOP
HEATER
DOOR
SWITCH FAN MOTOR
CONVECTION
MOTOR
Q2  2SB1238
R4  27
R5  4.7k
R3  510 1/2w
R2  510 1/2w
RY5
RY6
RY4Q3...