Sharp R820bk Service Manual

19
R-820BK
R-820BW
The following test procedure should be carried out with the microwave oven is a fully assembled
condition (outer case fitted).
It is difficult to measure the exact temperature in the convection oven. An accurate thermocouple type
temperature tester must be used. A low priced bi-metal type thermometer is not reliable or accurate.
The temperature should be checked with outer case cabinet installed, approx. 5 minutes after preheat
temperature is reached (audible signal sounds four times)....

20
R-820BK
R-820BW
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
MKEY UNIT 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 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...

21
R-820BK
R-820BW
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
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.
5. Reconnect all leads removed from components during testing.
6. Re-install the outer case (cabinet).
7. Reconnect...

22
R-820BK
R-820BW
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
WARNING : The oven should be fully assembled before following procedure.
(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 once and touch the Number pad 1, 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
WEIGHT1ST STAGE 2ND STAGE 3RD STAGE 4TH STAGE
LEVEL TIME...

23
R-820BK
R-820BW
TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
STEPS OCCURRENCE CAUSE OR CORRECTION
The rated AC voltage is not present between
1 Pin No. 1 of the 3-pin connector (A) and the Check supply voltage and oven power cord.
common terminal of the relay RY6.
2The rated AC voltage is present at primary Low voltage transformer or secondary circuit defective.
side of low voltage transformer. Check and repair.
8) Disconnect the power supply cord, and then remove outer case.
9) Open the door and...

24
R-820BK
R-820BW
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
4) ACL
A circuit to generate a signal which resets the LSI to the
initial state when power is supplied.
5) Buzzer Circuit
The buzzer is responsive to signals from the LSI to emit
audible sounds (key touch sound and completion sound).
6) Door Sensing Switch (Stop Switch)
A switch to tell the LSI if the door is open or closed.
7) Relay Circuit
To drive the magnetron, grill heaters, bottom heater,
convection motor, fan motor,...

25
R-820BK
R-820BW
DESCRIPTION OF LSI
LSI(IZA888DR)
The I/O signal of the LSI(IZA888DR) are detailed in the following table.
Pin No. Signal I/O Description
A
B
C
H: GND
L 0.1 sec
2.0 sec
1.0 sec
1.0 sec
16.7 msec.H : GND
L (-5V)
1 C1 IN Terminal not used.
2 VL1 IN
Power source voltage input terminal.
Standard voltage for LCD.
3-5 AN7-AN5 INHeating constant compensation terminal.
6 AN4 IN Terminal not used.
7 AN3 IN
Temperature measurement input: OVEN THERMISTOR.
By inputting DC voltage corresponding to...

26
R-820BK
R-820BW
Pin No. Signal I/O Description
VARI ON TIME OFF TIME
P-HI(100% power) 32 sec. 0 sec.
P-90(approx. 90% power) 30 sec. 2 sec.
P-80(approx. 80% power) 26 sec. 6 sec.
P-70(approx. 70% power) 24 sec. 8 sec.
P-60(approx. 60% power) 22 sec. 10 sec.
P-50(approx. 50% power) 18 sec. 14 sec.
P-40(approx. 40% power) 16 sec. 16 sec.
P-30(approx. 30% power) 12 sec. 20 sec.
P-20(approx. 20% power) 8 sec. 24 sec.
P-10(approx. 10% power) 6 sec. 26 sec.
P-0(0% power) 0 sec. 32 sec.
Power output ON time...

27
R-820BK
R-820BW
Pin No. Signal I/O Description
Power output ON time OFF time
100 % 48 sec. 0 sec.
90 % 44 sec. 4 sec.
80 % 40 sec. 8 sec.
70 % 36 sec. 12 sec.
60 % 32 sec. 16 sec.
50 % 26 sec. 22 sec.
40 % 22 sec. 26 sec.
30 % 16 sec. 32 sec.
20 % 12 sec. 36 sec.
10 % 8 sec. 40 sec.
ONOFF During
cooking
LGND H.(Convection)
ONOFF
For 5 minutes after grill, or for a 
while after convection or roust. 

LGND H.
39 XOUT OUTInternal clock oscillation frequency control output.
Output to control oscillation...

28
R-820BK
R-820BW
Pin No. Signal I/O Description
81 SEG9 OUTSegment data signal.
Connected to LCD. No connection in LCD.
82-90
SEG8-SEG0OUTSegment data signal.
Connected to LCD. Signal is similar to SEG39.
91 VCC IN Connected to GND.
92 VREF IN Connected to GND.
93 AVSS IN Connected to VC.
94 COM3 OUT
Common data signal: COM4.
Connected to LCD (Pin No. 36).
95 COM2 OUT
Common data signal: COM3.
Connected to LCD (Pin No. 35).
96 COM1 OUT
Common data signal: COM2.
Connected to LCD (Pin No. 34).
97 COM0...