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1900W/R-24AT
DOUBLE EXPRESS
QUANTITY DEFROST
11 1
12 2
13 3
14
4
15
5
16 6
17 7
18 8
19 9
20 0
MANUAL/ STOP / CLEAR
REHEAT
POWER LEVEL START
SET CHECK VOLUME
R-22AT
R-24AT
SERVICE MANUAL
SY520R24ATK//
COMMERCIAL
MICROWAVE OVEN
MODELS R-22AT
R-24AT
In interests of user-safety the oven should be restored to its
R-24AT
original condition and only parts identical to those specified
should be used.
This revised service manual is applied to
R-22AT from serial No. 050505509 and
R-24AT from serial No.
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R-22AT R-24AT SERVICING WARNING TO SERVICE PERSONNEL Microwave ovens contain circuitry capable of producing very high voltage and current. Contact with following parts will result in electrocution. High voltage capacitors, High voltage transformers, Magnetrons, High voltage rectifier assembly, High voltage fuses, High voltage harness. REMEMBER TO CHECK 4R REMEMBER TO CHECK 3D 1) Disconnect the supply. 1) Reconnect all leads removed from components dur- 2) Door opened, and wedged open. ing test
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R-22AT R-24AT SERVICE MANUAL PRODUCT SPECIFICATIONS COMMERCIAL MICROWAVE OVEN APPEARANCE VIEW R-22AT/ R-24AT GENERAL IMPORTANT INFORMATION OPERATING SEQUENCE This Manual has been prepared to provide Sharp Corp. Service engineers with Operation and Service Information. It is recommended that service engineers carefully study the FUNCTION OF IMPORTANT entire text of this manual, so they will be qualified to render COMPONENTS satisfactory customer service. CAUTION MICROWAVE RADIATION SERVICING AND
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R-22AT R-24AT PRODUCT DESCRIPTION SPECIFICATION ITEM DESCRIPTION Power Requirements 230 - 240 Volts 50 Hertz Single phase, 3 wire earthed Power Comsumption 2.4 kW Approx. 11 A [R-22AT] / 2.9 kW Approx. 13 A [R-24AT] Power Output 1500 W [R-22AT]/ 1900 W [R-24AT] nominal of RF microwave energy (measured by method of IEC 60705) Operating frequency 2450 MHz Case Dimensions Width Height Depth 510mm 335 mm 470mm Cooking Cavity Dimensions Width Height Depth 330 mm 180 mm 330mm Control Complement for To
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R-22AT R-24AT APPEARANCE VIEW OVEN 1. Control panel 11 10 5 4 3 2 2. Hole for safety door latches 19 14 18 3. Ceramic floor 4. Splash cover 5. Oven light 1 6. Air intake filter 15 7. Air intake openings 17 8. Oven cavity 8 16 13 9. Door seals and sealing surfaces 10. Door hinges 11. Oven door with see-through window 12. Door safety latches 13. Door handle. 12 9 7 6 14. Outer cabinet 15. Removable cover over oven light bulb AUTO TOUCH CONTROL PANEL 16. Air vent openings 17. Power supply cord 18 M
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R-22AT R-24AT OPERATION SEQUENCE Closing the door activates all door interlock switches to negative voltage of approximately 4000 volts D.C.. (interlock switches and stop switch). 3. The 2450 MHz microwave energy produced in the magnetron generates a wave length of 12.24 cm. This IMPORTANT energy is channelled through the waveguide (transport When the oven door is closed, the monitor switch contacts channel) into the oven cavity, where the food is placed COM-NC must be open. When the microwave o
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C1: H.V. CAPACITOR C2: H.V. CAPACITOR R-22AT R-24AT 48 sec. ON Number key 44sec. ON Number key 9 40 sec. ON Number key 8 36 sec. ON Number key 7 32 sec. ON Number key 6 26 sec. ON Number key 5 22 sec. ON Number key 4 16 sec. ON Number key 3 12 sec. ON Number key 2 8 sec. ON Number key 1 0 sec. ON Number key 0 NOTE: The ON/OFF time ratio does not exactly corre- spond to the percentage of microwave power, because approx. 3 seconds are needed for heat- ing up the magnetron filament. TWO MAGNETRO
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R-22AT R-24AT FUNCTION OF IMPORTANT COMPONENTS 3. If the door is opened and the interlock switch SW1 (or DOOR OPEN MECHANISM SW2) contacts fail to open, the fuse F1 F10A (or F2 1. The door release lever is pulled. F10A) blows simultaneously with closing of the monitor 2. The upper latch head is lifted up by the linked door switch SW3 (or SW4) contacts. release lever. CAUTION:BEFORE REPLACING A BLOWN FUSE F1 3. The head lever is lifted up by the door release lever. F10A (OR F2 F10A) TEST THE INT
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R-22AT R-24AT EXHAUST OVEN THERMISTOR TH3 BLOWER MOTOR BM The thermistor is a negative temperature coefficient type. The blower motor BM drives a blade which draws external The temperature in the exhaust duct is detected through cool air into the oven. This cool air is directed through the the resistance of the thermistor. air vanes surrounding the magnetrons and cools the If the temperature is high, the control panel will display magnetrons. This air is channelled through the oven cavity “EE7”
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R-22AT R-24AT EEP ROM I-2 N KEY UNIT TOUCH CONTROL TRANSFORMER T3 Due to programme lock Over the max. cooking time No power at wall outlet HOME FUSE or BREAKER Mis adjustment of switches P FUSE 2.5A O RELAY RY-4 O RELAY RY-3 O RELAY RY-1 M TOUCH CONTROL PANEL Opened wire harness Shorted wire harness POWER SUPPLY CORD K NOISE FILTER OVEN LAMP OR SOCKET J BLOWER MOTOR BM J ANTENNA MOTORS SM I EXHAUST THERMISTOR TH3 I MAGNETRON THERMISTOR (Lower) TH2 I MAGNETRON THERMISTOR (Upper) TH1 L HIGH VOLT
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R-22AT R-24AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST A MAGNETRON TEST NEVER TOUCH ANY PART IN THE CIRCUIT WITH YOUR HAND OR AN INSULATED TOOL WHILE THE OVEN IS IN OPERATION. CARRY OUT 3D CHECKS. Isolate the magnetron from high voltage circuit by removing all leads connected to filament terminal. To test for an open circuit filament use an ohmmeter to make a continuity test between the magnetron filament terminals, the meter should show a reading of less than 1 ohm. To test for short cir
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R-22AT R-24AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST Room temperature ................................................................................................. T0 = 21°C Initial temperature .................................................................................................. T1 = 11°C Temperature after (28 + 3) = 31 sec [for R-22AT].................................................. T2 = 21°C Temperature after (22 + 3) = 25 sec [for R-24AT]...........................
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R-22AT R-24AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST B HIGH VOLTAGE TRANSFORMER TEST WARNING: High voltage and large currents are present at the secondary winding and filament winding of the high voltage transformer. It is very dangerous to work near this part when the oven is on. NEVER make any voltage measurements of the high-voltage circuits, including the magnetron filament. CARRY OUT 3D CHECKS. Disconnect the leads to the primary winding of the high voltage transformer. Disconnec
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R-22AT R-24AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST Table: Terminal Connection of Switch Plunger Operation COM to NO COM to NC COM; Common terminal, NO; Normally open terminal Released Open circuit Short circuit Depressed Short circuit Open circuit NC; Normally close terminal If incorrect readings are obtained, make the necessary switch adjustment or replace the switch. CARRY OUT 4R CHECKS. F WEAK POINT F3 TEST CARRY OUT 3D CHECKS. If the weak point F3 is blown, there could be a shorts
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L N R-22AT R-24AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST If the meter does not indicate above resistance, replace the thermistor. 3. CARRY OUT 4R CHECKS. J MOTOR WINDING TEST CARRY OUT 3D CHECKS. Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two terminals. Resistance of Blower motor should be approximately 60Ω . Resistance of Antenna motor should be approximately 8.8 kΩ . If incorrect readings are obtained, replace the motor. CARRY OUT 4R CHECK
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R-22AT R-24AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST f) A certain group of indicators do not light up. g) The figure of all digits flicker. 2-3 Other possible problems caused by defective control unit. a) Buzzer does not sound or continues to sound. b) Cooking is not possible. N KEY UNIT TEST CARRY OUT 3D CHECKS. 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 stop switch operates properly; th
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R-22AT R-24AT TEST PROCEDURES PROCEDURE LETTER COMPONENT TEST STEPS OCCURRENCE CAUSE OR CORRECTION 1 The rated AC voltage is not present at Check supply voltage and oven power cord. POWER terminal of CPU connector (CN-A). 2 The rated AC voltage is present at primary Touch control transformer or secondary circuit defective. side of touch control transformer. Check and repair. 3 Fuse on the PWB is open. Replace the fuse with new one. (CARRY OUT 3D CHECKS BEFORE REPAIR) NOTE: *At the time of these
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R-22AT R-24AT TOUCH CONTROL PANEL ASSEMBLY OUTLINE OF TOUCH CONTROL PANEL The touch control section consists of the following units as 2. Key Unit shown in the touch control panel circuit. The key unit is composed of a matrix circuit in which when a key it touched, one of signals P33 - P34 (1) Control Unit generated by the LSI, is passed through the key and (2) Key Unit returned to the LSI as one of signals P24 - P27. This The principal functions of these units and the signals model has 20 Memor
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R-22AT R-24AT DESCRIPTION OF LSI LSI(IXA222DR) The I/O signal of the LSI(IXA222DR) is detailed in the following table. Pin No. Signal I/O Description 1 VCC IN Power source voltage: GND. VC voltage of power source circuit input. Connected to GND. 2 VEE IN Anode (segment) of Fluorescent Display light-up voltage: -35V. Vp voltage of power source circuit input. 3 AVSS IN Reference voltage input terminal. A reference voltage applied to the A/D converter in the LSI. Connected to DC. (-5V) 4 VREF IN Re
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R-22AT R-24AT Pin No. Signal I/O Description 0.12 sec 19 P47 OUT Signal to sound buzzer. GND A This signal is to control the 2.5kHz -5V 2.4 sec continuous signal. 1.2 sec 1.2 sec A: Switch touch sound. B C B: Guidance sound. T C: Completion sound. 200 sec. 200 sec. 20-21 P46-P45 - Terminal not used. 22 P44 OUT Oven lamp, Blower motor and Antenna motor driving signal (Square Waveform : 50Hz). During cooking To turn on and off the shut-off relay (RY1). H The Square waveform voltage is delivered L
