Sharp R820jsf Service Manual

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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). The...

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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 the door...

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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 the...

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TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
(2)Close the door, touch the Auto 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 Auto Defrost cooking condition.
(4) The oven will operate as follows
WEIGHT1ST STAGE 2ND STAGE 3RD STAGE 4TH STAGE
(Ground meat)LEVEL TIME LEVEL TIME LEVEL TIME LEVEL TIME
0.5lb 70% 50sec. 0% 1min. 50% 35sec. 30% 45sec.
(5) If improper operation is indicated, the control unit is probably...

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TEST PROCEDURES
PROCEDURE
LETTERCOMPONENT TEST
9) Open the door and block it open.
10) Discharge high voltage capacitor.
11) Reconnect all leads removed from components during testing.
12) Re-install the outer case (cabinet).
13) Reconnect the power supply cord after the outer case is installed.
14) Run the oven and check all functions.
TOUCH CONTROL PANEL ASSEMBLY
OUTLINE OF TOUCH CONTROL PANEL
3) Synchronizing Signal Circuit
The power source synchronizing signal is available in
order to...

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DESCRIPTION OF LSI
LSI
The I/O signal of the LSI are detailed in the following table.
Pin No. Signal I/O Description
1C1INTerminal not used.
2VL1 IN
Power source voltage input terminal.
Standard voltage for LCD.
3-6 AN7-AN4 INHeating constant compensation terminal.
7AN3 IN
Temperature measurement input: OVEN THERMISTOR.
By inputting DC voltage corresponding to the temperature detected by the thermistor,
this input is converted into temperature by the A/D converter built into the LSI.
8AN2 IN...

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Pin No. Signal I/O Description
26 P40 OUT
Bottom heater driving signal.
To turn on and off the bottom relay (RY4).
L level during grill (TOP AND BOTTOM)
cooking, Convection cooking or Roast
cooking, H level otherwise.
The heater relay turns on and off within a
48 second time base in accordance with
the special program in LSI.
27 P77 OUTConvection motor driving signal.
To turn on and off shut-off relay(RY1). L
level during CONVECTION; H level oth-
erwise. (Relay RY1 does not turn on at...

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Pin No. Signal I/O Description
35 RESET IN
Auto clear terminal.
Signal is input to reset the LSI to the initial state when power is applied. Temporarily
set to L level the moment power is applied, at this time the LSI is reset. Thereafter
set at H level.
36 XCIN IN Terminal not used.
37 XOUT IN Terminal not used.
38 XIN IN
Internal clock oscillation frequency input setting.
The internal clock frequency is set by inserting the ceramic filter oscillation circuit with
respect to OUT terminal.
39...

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Pin No. Signal I/O Description
51-90
SEG39-SEG0OUTSegment data signal.
Connected to LCD. No connection in LCD.
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 OUT
Common data signal: COM1.
Connected to LCD (Pin No. 33).
98-99 VL3-VL2 IN
Power...

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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 protect...