SERVICE MANUAL R-3S56 SHARP CORPORATION MICROWAVE OVEN MODEL

Transcription

1 SRVIC MANUAL S9510R3S56PX/ MICROWAV OVN MODL In interests of user-safety the oven should be restored to its original condition and only parts identical to those specified should be used. TAL OF CONTNTS Page CAUTION, MICROWAV RADIATION... 1 WARNING... 1 PRODUCT SPCIFICATIONS... 2 GNRAL INFORMATION... 2 APPARANC VIW... 3 OPRATION SQUNC... 4 FUNCTION OF IMPORTANT COMPONNTS... 5 SRVICING... 6 TST PROCDUR... 8 TOUCH CONTROL PANL COMPONNT RPLACMNT AND ADJUSTMNT PROCDUR MICROWAV MASURMNT WIRING DIAGRAM PICTORIAL DIAGRAM CONTROL PANL CIRCUIT PRINTD WIRING OARD PARTS LIST SHARP CORPORATION

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3 SRVIC MANUAL MICROWAV OVN PRODUCT SPCIFICATIONS GNRAL IMPORTANT INFORMATION 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 entire text of this manual, so they will be qualified to render satisfactory customer service. CAUTION MICROWAV RADIATION DO NOT COM XPOSD TO RADIATION FROM TH MICROWAV GNRATOR OR OTHR PARTS CONDUCTING MICROWAV NRGY. Service engineers should not be exposed to the microwave energy which may radiate from the magnetron or other microwave generating devices if it is improperly used or connected. All input and output microwave connections, waveguides, flanges and gaskets must be secured. Never operate the device without a microwave energy absorbing load attached. Never look into an open waveguide or antenna while the device is energized. APPARANC VIW OPRATING SQUNC FUNCTION OF IMPORTANT COMPONNTS SRVICING AND TROULSHOOTING CHART TST PROCDUR TOUCH CONTROL PANL ASSMLY WARNING Never operate the oven until the following points are ensured. (A) The door is tightly closed. () The door brackets and hinges are not defective. (C) The door packing is not damaged. (D) The door is not deformed or warped. () There is not any other visible damage with the oven. Servicing and repair work must be carried out only by trained service engineers. All the parts marked "*" on parts list are used at voltages more than 250V. Removal of the outer wrap gives access to potentials above 250V. All the parts marked " " on parts list may cause undue microwave exposure, by themselves, or when they are damaged, loosened or removed. COMPONNT RPLACMNT AND ADJUSTMNT PROCDUR MICROWAV MASURMNT WIRING DIAGRAM PARTS LIST SHARP CORPORATION OSAKA, JAPAN 1

4 PRODUCT SPCIFICATIONS ITM DSCRIPTION Power Requirements 220 Volts 50 Hertz Single phase, 3 wire earthed Power Consumption 1.06 kw, Approx. 4.9A Power Output 700 watts nominal of RF microwave energy (IC 705) Operating fequency 2450 MHz Case Dimensions Width 450 mm Height 295 mm including foot Depth 361 mm Cooking Cavity Dimensions Width 285 mm Height 178 mm Depth 313 mm Turntable diameter 272mm Control Complement Touch Control System Timer (0-99 minutes 90 seconds) Microwave Power for Variable Cooking Repetition Rate; HIGH... Full power throughout the cooking time MDIUM HIGH... approx. 70% of FULL Power MDIUM... approx. 50% of FULL Power MDIUM LOW... approx. 30% of FULL Power LOW... approx. 10% of FULL Power TIM pads AUTO COOK pad STOP/CLAR pad SRVS/POWR LVL pad START/INSTANT COOK pad AUTO COOK MNUS Set Weight (Approx.) 14 kg GNRAL INFORMATION WARNING THIS APPLIANC MUST ARTHD IMPOTANT TH WIRS IN THIS MAINS LAD AR COLOURD IN ACCORDANC WITH TH FOLLOWING COD: GRN-AND-YLLOW LU ROWN : ARTH : NUTRAL : LIV 2

5 APPARANC VIW 1. Ventilation opening 2. Oven lamp 3. Door hinges 4. Door safety latches 5. See through door 6. Coupling 7. Door open button 8. Touch control panel 9. Digital read-out 10.Wave guide cover 11.Power supply cord 12. arth wire TOUCH CONTROL PANL a a. TIM PADS Press to enter cooking time. b. AUTO COOK PAD Press to select AUTO COOK menu. c. POWR LVL/SRVS PAD Press to select microwave power setting. If not pressed, 100% is automatically selected. Press to enter serves after selecting AUTO COOK menu. d. STOP / CLAR PAD Press to clear during programming. Press once to stop operation of oven during cooking: press twice to cancel cooking programme. e. INSTANT COOK / START PAD Press once to cook for 1 minute at 100% or increase by 1 minute multiples each time this pad is pressed during cooking. Press to start oven after setting programmes. f. AUTO COOK MNUS b c d e f 3

6 OPRATION SQUNC OFF CONDITION Closing the door activates all door interlock switches (1st. latch switch, 2nd. latch switch and stop switch). IMPORTANT When the oven door is closed, the monitor switch contacts (COM-NC) must be open. When the microwave oven is plugged in a wall outlet, rated voltage is supplied to the point A3+A5 in the control unit. Figure O-1 on page The display shows " 0". NOT: When the oven door is opened, the oven lamp comes on at this time. MICROWAV COOKING CONDITION HIGH COOKING nter a desired cooking time with the touching Time key and start the oven with touching START key. Function sequence Figure O-2 on page 25 CONNCTD COMPONNTS Oven lamp, Fan motor, Turntable motor Power transformer RLAY RY1 RY2 1. Rated voltage is supplied to the primary winding of the power transformer. The voltage is converted to about 3.3 volts A.C. output on the filament winding and high voltage of approximately 2000 volts A.C. on the secondary winding. 2. The filament winding voltage (3.3 volts) heats the magnetron filament and the high voltage (2000 volts) is sent to the voltage doubling circuit, where it is doubled to negative voltage of approximately 4000 volts D.C.. 3. The 2450 MHz microwave energy produced in the magnetron generates a wave length of cm. This energy is channelled through the waveguide (transport channel) into the oven cavity, where the food is placed to be cooked. 4. When the cooking time is up, a signal tone is heard and the relays RY1+RY2 go back to their home position. The circuits to the oven lamp, power transformer, fan motor and turntable motor are cut off. 5. When the door is opened during a cook cycle, the switches come to the following condition. CONDITION DURING DOOR OPN SWITCH CONTACT COOKING (NO COOKING) 1st. latch switches COM-NO Closed Open 2nd. latch switch COM-NO Closed Open Monitor switch COM-NC Open Closed Stop switch COM-NO Closed Open The circuits to the power transformer, fan motor and turntable motor are cut off when the 1st. latch switch, 2nd. latch switch, and stop switch are made open. The oven lamp remains on even if the oven door is opened after the cooking cycle has been interrupted, because the relay RY1 stays closed. Shown in the display is the remaining time. 6. MONITOR SWITCH CIRCUIT The monitor switch is mechanically controlled by oven door, and monitors the operation of the 1st and 2nd. latch switches. 6-1 When the oven door is opened during or after the cycle of a cooking program, the 1st. latch and 2nd. latch switch must open their contacts first. After that the contacts (COM-NC) of the monitor switch can be closed When the oven door is closed, the contacts (COM-NC) of the monitor switch must be opened. After that the contacts of the 1st. latch, 2nd. latch and stop switch are closed and the contacts (COM-NO) of the stop switch can be opened When the oven door is opened and the contacts of the 1st and 2nd latch switches remain closed. The fuse M6.3A will blow, because the monitor switch is closed and a short circuit is caused. MDIUM HIGH, MDIUM, MDIUM LOW, LOW COOKING When the microwave oven is preset for variable cooking power, rated voltage is supplied to the power transformer intermittently within a 32-second time base through the relay contact which is coupled with the current-limiting relay. The following levels of microwave power are given. STTING; HIGH MDIUM HIGH MDIUM MDIUM LOW LOW 32 sec. ON 24 sec. ON 18 sec. ON 12 sec. ON 6 sec. ON 8 sec. OFF 14 sec. OFF 20 sec. OFF 26 sec. OFF Approx. 70% Approx. 50% Approx. 30% Approx. 10% NOT: The ON/OFF time ratio does not exactly correspond to the percentage of microwave power, because approx. 2 seconds are needed for heating up the magnetron filament. 4

7 FUNCTION OF IMPORTANT COMPONNTS DOOR OPN MCHANISM The door is opened by pushing the open button on the control panel, When the open button is pushed, the switch lever on the latch hook is moved upward, operating the latch head. The latch head is moved upward, and released from latch hook. Now, the door can be opened. DOOR LATCH HADS LATCH HOOK DOOR OPN UTTON MONITOR SWITCH 1ST. LATCH SWITCH STOP SWITCH 2ND. LATCH SWITCH SWITCH LVR Figure D-1. Door Open Mechanism 1ST. LATCH SWITCH, 2ND. LATCH SWITCH AND STOP SWITCH 1. When the oven door is closed, the contacts (COM-NO) must be closed. 2. When the oven door is opened, the contacts.(com-no) must be opened. MONITOR SWITCH 1. When the oven door is closed, the contacts (COM-NC) must be opened. 2. When the oven door is opened, the contacts (COM-NC) must be closed. 3. If the oven door is opened and the contacts (COM-NO) of the 1st latch switch and 2nd latch switch fail to open, the fuse blows simultaneously with closing the contacts (COM-NC) of the monitor switch. CAUTION: FOR RPLACING A FUS TST TH 1ST LATCH SWITCH, 2ND LATCH SWITCH, MONITOR SWITCH AND MONITOR RSIS- TOR FOR PROPR OPRATION. (RFR TO CHAPTR "TST PROCDUR") 2. If the wire harness or electrical components are shortcircuited, this fuse blows to prevent an electric shock or fire hazard. TMPRATUR FUS 150 C (MG) This fuse protects the magnetron against overheating. If the temperature goes up higher than 150 C because the fan motor is interrupted, the air inlet duct is blocked or the ventilation openings are obstructed, the fuse blows and cuts off the power supplying to the power transformer. The defective fuse must be replaced with new rated one. TMP. FUS 150 C (OVN) The temp. fuse located on the top of the oven cavity is designed to prevent damage to the oven if the foods in the oven catch fire due to over heating produced by improper setting of cook time or failure of control unit. Under normal operation, the temp. fuse remains closed. However, when abnormally high temperatures are reached within the oven cavity, the temp. fuse will open at 150 C, causing the oven to shut down. The defective fuse must be replace with a new one. THRMAL CUT-OUT 95 C The thermal cut-out protect the fan motor against overheat. If its temperature goes up higher than 95 C because the fan motor is locked or the ventilation openings are blocked, the contacts of the thermal cut-out will open and switches off the oven. When the oven cools itself down to 75 C, the contacts of the thermal cut-out will close again. TURNTAL MOTOR The turntable motor drives the roller stay to rotate the turntable. FAN MOTOR FM The fan motor drives a blade which draws external cool air. This cool air is directed through the air vanes surrounding the magnetron and cools the magnetron. This air is channelled through the oven cavity to remove steam and vapours given off from the heating foods. It is then exhausted through the exhausting air vents at the oven cavity MONITOR RSISTOR R 0.8Ω 20W The monitor resistor prevents the fuse bursting when the fuse blows due to the operation of the monitor switch. FUS 1. The fuse blows when the contacts (COM-NO) of the 1st latch switch and 2nd latch switch remain closed with the oven door open and when the monitor switch closes. 5

8 SRVICING WARNING TO SRVIC PRSONNL Microwave ovens contain circuitry capable of producing very high voltage and current, contact with any part of the high voltage circuit will result in electrocution. High voltage capacitor, Power transformer, Magnetron, High voltage rectifier assembly, High voltage harness. RMMR TO CHCK 3D RMMR TO CHCK 4R 1) Disconnect the supply. 2) Door opened, and wedged open. 3) Discharge high voltage capacitor. WARNING: AGAINST TH CHARG OF TH HIGH-VOLTAG CAPACITOR The high-voltage capacitor remains charged about 60 seconds after the oven has been switched off. Wait for 60 seconds and then short-circuit the connection of the high-voltage capacitor (that is, of the connecting lead of the high-voltage rectifier) against the chassis with the use of an insulated screwdriver. Sharp recommend that wherever possible fault-finding is carried out with the supply disconnected. It may in, some cases, be necessary to connect the supply after the outer case has been removed, in this event carry out 3D checks and then disconnect the leads to the primary of the power transformer. nsure that these leads remain isolated from other components and the oven chassis. (Use insulation tape if necessary.) When the testing is completed carry out 3D checks and reconnect the leads to the primary of the power transformer. 1) Reconnect all leads removed from components during testing. 2) Replace the outer case (cabinet). 3) Reconnect the supply. 4) Run the oven. Check all functions. Microwave ovens should not be run empty. To test for the presence of microwave energy within a cavity, place a cup of cold water on the oven turntable, close the door and set the microwave timer for two (2) minutes. Set the power level to HIGH and push the START button. When the two minutes has elapsed (timer at zero) carefully check that the water is now hot. If the water remains cold carry out 3D checks and re-examine the connections to the component being tested. When all service work is completed, and the oven is fully assembled, the microwave power output should be checked and microwave leakage test carried out TROULSHOOTING GUID 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 fuse M6.3A in the 1st. latch switch - 2nd. latch switch - monitor switch - monitor resistor circuit, check the 1st. latch switch, 2nd. latch switch, monitor switch and monitor resistor before replacing the fuse M6.3A. 6

9 CK = Check / R = Replace TST PROCDUR AC CK D FGGG H H I JLMR CKCKR CKCKCKCKCK K CONDITION OFF CONDITION ON CONDITION POSSIL CAUS AND DFCTIV PARTS PROLM Home fuse blows when power supply cord is plugged into wall outlet. FUS M6.3A blows when power supply cord is plugged into wall outlet. " 0" does not appear in display but power supply cord is plugged into wall outlet. Display does not operate properly when STOP/CLAR pad is touched. Oven lamp does not light at door opened. (Display appears.) Oven does not start when the START pad is touched. (Display appears) Oven lamp does not light (Display appears.) Fan motor does not operate. (Display appears.) Turntable motor assembly does not operate. (Display appears.) Oven or any electrical parts does not stop when cooking time is 0 or STOP/CLAR pad is touched. Oven seems to be operating but little or no heat is produced in oven load. (Microwave power level is set at HIGH) Oven does not seems to be operating properly when M- DIUM HIGH, MDIUM, M- DIUM LOW or LOW is set. (Oven operates properly at HIGH and then the STOP/ CLAR pad is touched the oven stops.) Oven goes into cook cycle but shuts down before end of cooking cycle. MAGNTRON POWR TRANSFORMR H.V. RCTIFIR ASSMLY HIGH VOLTAG WIR HIGH VOLTAG CAPACITOR 1ST. LATCH SWITCH 2ND. LATCH SWITCH STOP SWITCH MONITOR SWITCH MONITOR RSISTOR TMPRATUR FUS 150 C (OVN) THRMAL CUT-OUT 95 C TMPRATUR FUS 150 C (MAG.) FAN MOTOR TURNTAL MOTOR FUS M6.3A TOUCH CONTROL PANL RLAY (RY-1, RY-2) FOIL PATRN ON P.W.. POWR SUPPLY CORD SHORTD WIR HARNSS OPND WIR HARNSS OVN LAMP OR SOCKT WALL OUTLT MISADJUSTMNT SWITCH HOM FUS OR RAKR LOCKD COOLING FAN LOCKD VNTILATION TACT SWITCH 7

10 TST PROCDURS PROCDUR LTTR COMPONNT TST A MAGNTRON TST NVR TOUCH ANY PART IN TH CIRCUIT WITH YOUR HAND OR AN INSULATD TOOL WHIL TH OVN IS IN OPRATION. CARRY OUT 3D CHCKS. 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 filament to anode condition, connect ohmmeter between one of the filament terminals and the case of the magnetron (ground). This test should be indicated an infinite resistance. If a low or zero resistance reading is obtained then the magnetron should be replaced. MICROWAV OUTPUT POWR (IC 705) The following test procedure should be carried out with the microwave oven in a fully assembled condition (outer case fitted). Microwave output power from the magnetron can be measured by way of IC 705, i.e. it can be measured by using water load how much it can be absorbed by the water load. To measure the microwave output power in the microwave oven, the relation of calorie and watt is used. When P(W) heating works for t(second), approximately P x t/4.187 calorie is generated. On the other hand, if the temperature of the water with V(ml) rises T ( C) during this microwave heating period, the calorie of the water is V x T. The formula is as follows; P x t / = V x T P (W) = x V x T / t Our condition for water load is as follows: Room temperature...around 20 C Power supply Voltage...Rated voltage Water load g Initial temperature...10±2 C Heating time...60 sec. P = 70 x T Measuring condition: 1. Container The water container must be a cylindrical borosilicate glass vessel having a maximum material thickness of 3 mm and an outside diameter of approximately 190 mm. 2. Temperature of the oven and vessel The oven and the empty vessel are at ambient temperature prior to the start the test. 3. Temperature of the water The initial temperature of the water is (10±2) C. 4. Select the initial and final water temperature so that the maximum difference between the final water temperature and the ambient temperature is 5 C. 5. Select stirring devices and measuring instruments in order to minimize addition or removal of heat. 6. The graduation of the thermometer must be scaled by 0.1 C at minimum and accurate thermometer. 7. The water load must be (1000±5) g. 8. t is measured while the microwave generator is operating at full power. Magnetron filament heatup time is not included. NOT: The operation time of the microwave oven is t + 2 sec. 2 sec. is magnetron filament heat-up time. Measuring method: 1. Measure the initial temperature of the water before the water is added to the vessel. (xample: The initial temperature T1 = 11 C) 2. Add the 1 litre water to the vessel. 3. Place the load on the centre of the shelf. 4. Operate the microwave oven at HIGH for the temperature of the water rises by a value T of (10 ± 2) C. 5. Stir the water to equalize temperature throughout the vessel. 8

11 TST PROCDURS PROCDUR LTTR COMPONNT TST 6. Measure the final water temperature. (xample: The final temperature T2 = 21 C) 7. Calculate the microwave power output P in watts from above formula. Initial temperature... T1 = 11 C Temperature after (60 + 2) = 62 sec.... T2 = 21 C Temperature difference Cold-Warm... T1 = 10 C Measured output power The equation is P = 70 x T... P = 70 x 10 C = 700 Watts JUDGMNT: The measured output power should be at least ± 15 % of the rated output power. CAUTION: 1 C CORRSPONDS TO 70 WATTS RPAT MASURMNT IF TH POWR IS INSUFFICINT. 1000g 1000g 1000g T1 C Heat up for62 sec. T2 C POWR TRANSFORMR TST WARNING: High voltages and large currents are present at the secondary winding and filament winding of the power transformer. It is very dangerous to work near this part when the oven is on. NVR make any voltage measurements of the high-voltage circuits, including the magnetron filament. CARRY OUT 3D CHCKS. Disconnect the leads to the primary winding of the power transformer. Disconnect the filament and secondary winding connections from the rest of the HV circuitry. Using an ohmmeter, set on a low range, it is possible to check the continuity of all three windings. The following readings should be obtained: a. Primary winding...approx Ω b. Secondary winding... approx Ω c. Filament winding...less than 1Ω If the reading obtained are not stated as above, then the power transformer is probably faulty and should be replaced. CARRY OUT 4R CHCKS. C HIGH VOLTAG RCTIFIR ASSMLY TST A CARRY OUT 3D CHCKS. High voltage rectifier Isolate the high voltage rectifier assembly from the HV circuit. The high voltage rectifier can be tested using an ohmmeter set to its highest range. Connect the ohmmeter across the terminal A+ of the high voltage rectifier and note the reading obtained. Reverse the meter leads and note this second reading. The normal resistance is infinite in one direction and more than 100 kω in the other direction. 9

12 TST PROCDURS (CONT'D) PROCDUR LTTR COMPONNT TST CARRY OUT 4R CHCKS. NOT: FOR MASURMNT OF TH RSISTANC OF TH RCTIFIR, TH ATTRIS OF TH MASURING INSTRUMNT MUST HAV A VOLTAG AT LAST 6 VOLTS, CAUS OTHRWIS AN INFINIT RSISTANC MIGHT SHOWN IN OTH DIRCTIONS. D F HIGH VOLTAG CAPACITOR TST CARRY OUT 3D CHCKS. A. Isolate the high voltage capacitor from the circuit.. Continuity check must be carried out with measuring instrument which is set to the highest resistance range. C. A normal capacitor shows continuity for a short time (kick) and then a resistance of about 10MΩ after it has been charged. D. A short-circuited capacitor shows continuity all the time.. An open capacitor constantly shows a resistance about 10 MΩ because of its internal 10MΩ resistance. F. When the internal wire is opened in the high voltage capacitor shows an infinite resistance. G. The resistance across all the terminals and the chassis must be infinite when the capacitor is normal. If incorrect reading are obtained, the high voltage capacitor must be replaced. CARRY OUT 4R CHCKS. SWITCH TST CARRY OUT 3D CHCKS. Isolate the switch to be tested and using an ohmmeter check between the terminals as described in the following table. COM; Common terminal, Table: Terminal Connection of Switch NO; Normally open terminal Plunger Operation COM to NO COM to NC NC; Normally close terminal Released O.C. S.C. S.C.; Short circuit Depressed S.C. O.C. O.C.; Open circuit If incorrect readings are obtained, make the necessary switch adjustment or replace the switch. CARRY OUT 4R CHCKS. MONITOR RSISTOR TST CARRY OUT 3D CHCKS. Disconnect the leads from the monitor resist. Using an ohmmeter and set on a low range. Check between the terminals of the monitor resistor. The resistance of monitor resistor is approx. 0.8 ohms. If incorrect readings are obtained, replace the monitor resistor. CARRY OUT 4R CHCKS. G TMPRATUR FUS OR THRMAL CUT-OUT TST CARRY OUT 3D CHCKS. Disconnect the leads from the terminals of the temperature fuse or thermal cut-out. Then using an ohmmeter, make a continuit test across the two terminals as described in the below. CARRY OUT 4R CHCKS. Table: Thermal cut-out Test Temperature of "ON" condition Temperature of "OFF" condition Indication ofohmmeter Parts Name (closed circuit) ( C) (open circuit) ( C) (When room temperature is approx. 20 C) Temperature fuse 150 C This is not resetable type. Above 150 C Closed circuit. Thermal cut-out 95 C elow 75 C Above 95 C Closed circuit. 10

13 TST PROCDURS (CONT'D) PROCDUR LTTR H COMPONNT TST If incorrect readings are obtained, replace the temp. fuse or thermal cut-out. An open circuit temperature fuse (MAG.) indicates that the magnetron has overheated, this may be due to resistricted ventilation, cooling fan failure. An open circuit temperature fuse (OVN) indicates that the oven cavity has overheated, this may be due to no load operation. An open circuit thermal cut-out 95 C indicates that the fan motor winding has overheated, this may be due to resisted ventilation or locked cooling fan. MOTOR WINDING TST CARRY OUT 3D CHCKS. Disconnect the leads from the motor. Using an ohmmeter, check the resistance between the two terminals as described in the table below. Table: Resistance of Motor Motors Resistance Fan motor Approximately 330 Ω Turntable motor Approximately 12 kω If incorrect readings are obtained, replace the motor. CARRY OUT 4R CHCKS. I J FUS CARRY OUT 3D CHCKS. If the fuse is blown when the door is opened, check the 1st latch switch, 2nd latch switch, monitor switch and monitor resistor. If the fuse is blown by incorrect door switching replace the defective switch(s) and the fuse. If the fuse is blown, there is a shorts or grounds in electrical parts or wire harness. Check them and replace the defective parts or repair the wire harness. CARRY OUT 4R CHCKS. CAUTION: Only replace fuse with the correct value replacement. TOUCH CONTROL PANL ASSMLY TST The touch control panel consists of circuits including semiconductors such as LSI, ICs, etc. Therefore, unlike conventional microwave ovens, proper maintenance cannot be performed with only a voltmeter and ohmmeter. In this service manual, the touch control panel assembly is in one unit, and troubleshooting by unit replacement is described according to the symptoms indicated. 1. Tact Switch. The following symptoms indicate a defective tact switch. Replace the tact switch. a) When touching the tact switches, a certain tact switch produces no signal at all. b) When touching the tact switches, sometimes a tact switch produces no signal. 2. Control Panel The following symptoms may indicate a defective control unit. efore replacing the control unit, perform the tact switch test (Procedure K) to determine if control unit is faulty. 2-1 In connection with tact switches. a) When touching the tact switches, a certain group of tact switches do not produce a signal. b) When touching the tact switches, no tact switches produce a signal. 2-2 In connection with indicators a) At a certain digit, all or some segments do not light up. b) At a certain digit, brightness is low. c) Only one indicator does not light. 11

14 TST PROCDURS (CONT'D) PROCDUR LTTR K COMPONNT TST d) The corresponding segments of all digits do not light up or they continue to light up. e) Wrong figure appears. 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) uzzer does not sound or continues to sound. b) Cooking is not possible. TACT SWITCH TST If the display fails to clear when the STOP/CLAR tact switch is depressed, first 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 sensing switch(stop switch) is good, make sure the door sensing switch is closed (either close the door or short the door sensing switch connecter). Use the tact switch matrix indicated on the control panel schematic and place a jumper wire between the pins that correspond to the STOP/CLAR tact switch making momentary contact. If the control unit responds by clearing with a beep, the tact switch is faulty and must be replaced. If the control unit does not respond, it is a 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 tact switch is at fault. SW1 10 SW2 1 SW3 10 MIN. MIN. SC. SW4 SW5 SW6 START/ STOP AUTO COOK INSTANT COOK CLAR SW7 SRVS/ POWR LVL L RLAY TST CARRY OUT 3D CHCKS. Remove the outer case and check voltage between Pin Nos. 3 and 5 of the 3 pin connector (A) on the control unit with an A.C. voltmeter. The meter should indicate 220 volts, if not check oven circuit. RY1 and RY2 Relay Test These relays are operated by D.C. voltage Check voltage at the relay coil with a D.C. voltmeter during the microwave cooking or convection cooking operation. DC. voltage indicated... Defective relay. DC. voltage not indicated.... Check diode which is connected to the relay coil. If diode is good, RLAY SYMOL OPRATIONAL VOLTAG CONNCTD COMPONNTS RY1 Approx. 19.0V.D.C. Oven lamp/turntable motor/cooling fan motor RY2 Approx. 18.0V.D.C. Power transformer CARRY OUT 4R CHCKS. M PROCDURS TO TAKN WHN TH FOIL PATTRN ON TH PRINTD WIRING OARD (PW) IS OPN To protect the electronic circuits, this model is provided with a fine foil pattern added to the primary on the PW, this foil pattern acts as a fuse. If the foil pattern is open, follow the troubleshooting guide given below for repair. Problem: POWR ON, indicator does not light up. CARRY OUT 3D CHCKS. 12

15 TST PROCDURS (CONT'D) PROCDUR LTTR COMPONNT TST STPS OCCURANC CAUS OR CORRCTION 1 The rated voltage is not applied to POWR terminal of CPU connector (CN-A) 2 The rated voltage is applied to primary side of power transformer. Check supply voltage and oven main unit. Power transformer or secondary circuit defective. Check and repair. 3 Only pattern at "a" is broken. *Insert jumper wire J1 and solder. 4 Pattern at "a" and "b" are broken. *Insert the coil RCILF2003YAZZ between "c" and "d". NOT: At the time of these repairs, make a visual inspection of the varistor for burning damage and examine the transformer with tester for the presence of layer short-circuit (check primary coil resistance). If any abnormal condition is detected, replace the defective parts. CARRY OUT 4R CHCKS. D82 d VRS1 b c (J1) CN-A a POWR 5 RY2 13

16 TOUCH CONTROL PANL ASSMLY OUTLIN OF TOIUCH CONTROL PANL Control Unit Control unit consists of tact switches, LSI, power source circuit, synchronizing signal circuit, ACL circuit, buzzer circuit and indicator circuit. 1) Tact Switches The tact switches are composed of a matrix, signals generated in the LSI are sent to the tact switches through R60-R62. When a tact switches is touched, a signal is completed through the tact switches and passed back to the LSI through R81-R83 to perform the function that was requested. 2) LSI This LSI controls the key strobe signal, relay driving signal for oven function and indicator signal. 3) Power Source Circuit This circuit generates voltages necessary in the control unit. Symbol Voltage Application VC -5V LSI(IC1) 4) Synchronizing Signal Circuit The power source synchronizing signal is available in order to compose a basic standard time in the clock circuit. It accompanies a very small error because it works on commercial frequency. 5) ACL Circuit A circuit to generate a signals which resets the LSI to the initial state when power is supplied. 6) uzzer Circuit The buzzer is responsive to signals from the LSI to emit noticing sounds (key touch sound and completion sound). 7) Door Sensing Switch A switch to tell the LSI if the door is open or closed. 8) Relay Circuit To drive the magnetron, fan motor, turntable motor and light the oven lamp. 9) Indicator Circuit Indicator element is a Light-emitting diode. asically, a Light-emitting diode is triode having a cathode and an anode. The Light-emitting diode has 4-digits, 8-segments are used for displaying figures. 14

17 DSCRIPTION OF LSI LSI(IZA588DR): The I/O signal of the LSI(IZA588DR) is detailed in the following table. Pin No. Signal I/O Description 1 XOUT OUT Internal clock oscillation frequency control output. Output to control oscillation input of XOUT. 2 XIN IN Internal clock oscillation frequency input setting. The internal clock frequency is set by inserting the ceramic filter oscillation circuit with respect to XIN terminal. 3 RST IN Auto clear terminal. Signal is input to reset the LSI to the initial state when power is supplied. Temporarily set to L level the moment power is supplied, at this time the LSI is set. Thereafter set at H level. 4 R70 OUT Magnetron high-voltage circuit driving signal. To turn on and off the cook relay. In Low operation, the signals holds L level during microwave cooking and H level while not cooking. In other cooking modes (70%,50%,30%,10%) the signal turns to L level and H level in repetition according to the power level. 5 R71 OUT Oven lamp,turntable motor and cooling fan motor driving signal. (Square Waveform : 50Hz) To turn on and off the control relay. The pulse signal (50Hz) is delivered to the control relay driving circuit and cook relay control circuit. 6 R72 OUT Terminal not used R40 - R43 OUT Digit selection signal. Refer to the touch control panel circuit about the relation between signals and digits. Normally, one pulse is output in every synchronized signal period, and input to the light emitting diode R50 - R52 OUT Segment data signal. Refer to the touch control panel circuit for the relationship between signals and indicators. Normally, one pulse is output in every synchronized signal period, and input to the anode of the light emitting diode. 14 VSS IN Connected to VC. 15 R53 OUT Segment data signal. Signal similar to R R60 OUT Segment data signal. Signal similar to R50. Switch strobe signal. Signal applied to tact switch section. A pulse signal is input to R81-R83 terminal while one of diode D91 line switches on switch matrix is touched. 17 R61 OUT Segment data signal. Signal similar to R50. Switch strobe signal. Signal applied to tact switch section. A pulse signal is input to R81-R83 terminal while one of diode D92 line switches on switch matrix is touched. 18 R62 OUT Segment data signal. Signal similar to R50. Switch strobe signal. Signal applied to tact switch section. A pulse signal is input to R81-R83 terminal while one of diode D93 line switches on switch matrix is touched. 19 R63 OUT Segment data signal. Signal similar to R INT2 IN Signal synchronized with commercial source frequency(50hz). This is basic timing for time processing of LSI. 15

18 Pin No. Signal I/O Description 21 R81 IN Signal coming from touch tact switch. When either one of resistor R93 line switches on switch matrix is touched, a corresponding signal will be input into R R82 IN Signal coming from touch tact switch. When either one of resistor R92 line switches on switch matrix is touched, a corresponding signal will be input into R R83 IN Signal coming from touch tact switch. When either one of resistor R91 line switches on switch matrix is touched, a corresponding signal will be input into R R90 OUT Terminal not used. 25 SO OUT Signal to sound buzzer. A: key touch sound(0.12 sec.). : Completion sound(2.4 sec.). 26 SCK OUT Connected to GND. (Pull up through resistor R2) 27 KO IN Input signal which communicates the door open/close information to LSI. Door closed; H level signal. Door opened; L level signal. 28 VDD IN Connected to GND. 16

19 SRVICING 1. Precautions for Handling lectronic 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 CMOS LSI. 1) When storing and transporting, thoroughly wrap them in aluminium foil. Also wrap all PW boards containing them in aluminium foil. 2) When soldering, ground the technician as shown in the figure and use grounded soldering iron and work table. approx. 1M ohm 2. Shapes of lectronic Components IC LM7905CT C Transistor KRA101M KRA222M KRA223M KRC243M 3. Servicing of Touch Control Panel We describe the procedures to permit servicing of the touch control panel of the microwave oven and the precautions you must take when doing so. To perform the servicing, power to the touch control panel is available either from the power line of the oven itself or from an external power source. (1) Servicing the touch control panel with power supply of the oven: CAUTION: TH HIGH VOLTAG TRANSFORMR OF TH MI- CROWAV OVN IS STILL LIV DURING SRVIC- ING PRSNTS A HAZARD. Therefore, when checking the performance of the touch control panel, put the outer cabinet on the oven to avoid touching the high voltage transformer, or unplug the primary terminal (connector) of the high voltage transformer to turn it off; the end of such connector must be insulated with an insulating tape. After servicing, be sure to replace the leads to their original locations. A. On some models, the power supply cord between the touch control panel and the oven itself is so short that the two can t be separated. For those models, check and repair all the controls (sensor-related ones included) of the touch control panel while keeping it connected to the oven.. On some models, the power supply cord between the touch control panel and the oven proper is long enough that they may be separated from each other. For those models, therefore, it is possible to check and repair the controls of the touch control panel while keeping it apart from the oven proper; in this case you must short both ends of the door sensing switch (on PW) of the touch control panel with a jumper, which brings about an operational state that is equivalent to the oven door being closed. As for the sensor-related controls of the touch control panel, checking them is possible if dummy resistor(s) with resistance equal to that of the controls are used. (2) Servicing the touch control panel with power supply from an external power source: Disconnect the touch control panel completely from the oven proper,and short both ends of the door sensing switch (on PW) of the touch control panel,which brings about an operational state that is equivalent to the oven door being closed. Connect an external power source to the power input terminal of the touch control panel, then it is possible to check and repair the controls of the touch control panel it is also possible to check the sensorrelated controls of the touch control panel by using the dummy resistor(s). 4. Servicing Tools Tools required to service the touch control panel assembly. 1) Soldering iron: 30W (It is recommended to use a soldering iron with a grounding terminal.) 2) Oscilloscope: Single beam, frequency range: DC-10MHz type or more advanced model. 3) Others: Hand tools 5. Other Precautions 1) efore turning on the power source of the control unit, remove the aluminium foil applied for preventing static electricity. 2) After aluminium foil is removed, be careful that abnormal voltage due to static electricity etc. is not applied to the input or output terminals. 3) Attach connectors, electrolytic capacitors, etc. to PW, making sure that all connections are tight. 4) e sure to use specified components where high precision is required. 17

20 COMPONNT RPLACMNT AND ADJUSTMNT PROCDUR WARNING: Avoid possible exposure to microwave energy. Please follow the instructions below before operating the oven. 1. Disconnect oven from power supply. 2. Make sure that a definite click can be heard when the microwave oven door is unlatched. (Hold the door in a closed position with one hand, then push the door open button with the other, this causes the latch leads to rise, it is then possible to hear a click as the door switches operate.) 3. Visually check the door and cavity face plate for damage (dents, cracks, signs of arcing etc.). Carry out any remedial work that is necessary before operating the oven. Do not operate the oven if any of the following conditions exist; 1. Door does not close firmly. 2. Door hinge, support or latch hook is damaged. 3. The door gasket or seal or damaged. 4. The door is bent or warped. 5. There are defective parts in the door interlock system. 6. There are defective parts in the microwave generating and transmission assembly. 7. There is visible damage to the oven. Do not operate the oven: 1. Without the RF gasket (Magnetron). 2. If the wave guide or oven cavity are not intact. 3. If the door is not closed. 4. If the outer case (cabinet) is not fitted. Please refer to OVN PARTS, CAINT PARTS, DOOR PARTS, when carrying out any of the following removal procedures: To remove the outer case proceed as follows. 1. Disconnect oven from power supply. 2. Open the oven door and wedge it open. 3. Remove the eight (8) screws from rear and along the side edge of case. 4. Slide the entire case back about 3cm to free it from retaining clips on the cavity face plate. 5. Lift the entire case from the unit. OUTR CAS RMOVAL 6. Discharge the H.V. capacitor before carrying out any further work. 7. Do not operate the oven with the outer case removed. N..; Step 1, 2 and 7 form the basis of the 3D checks. CAUTION: DISCHARG HIGH VOLTAG CAPACITOR FOR TOUCHING ANY OVN COMPONNT OR WIRING. HIGH VOLTAG COMPONNTS RMOVAL (HIGH VOLTAG CAPACITOR AND HIGH VOLTAG RCTIFIR ASSMLY) To remove the components, proceed as follows. 1. CARRY OUT 3D CHCKS. 2. Lift up the HVC cover. 3. Disconnect the H.V. wire of the H.V. rectifier assembly from the power tramsformer. 4. Disconnect the filament lead of the power transformer from the H.V. capacitor. 5. Remove one (1) screw holding capacitor holder to rear cabinet. 6. Remove one (1) screw holding earth side terminal of high voltage rectifier assembly, and remove capacitor holder. 7. Disconnect all the leads and terminals of high voltage rectifier assembly from high voltage capacitor. 8. Disconnect the H.V. wire A from the H.V. rectifier, assy. CAUTION: WHN RPLACING HIGH VOLTAG RCTIFIR ASSMLY, NSUR THAT TH CATHOD (ARTH) CONNCTION IS SCURLY FIXD TO TH CAPACITOR HOLDR WITH AN ARTHING SCRW. CAUTION: DO NOT RPLAC ONLY HIGH VOLTAG RCTIFIR. WHN RPLACING IT, RPLAC HIGH VOLTAG RCTIFIR ASSMLY. 9. Now H.V. rectifier assy. and H.V. copacitor. Should be free. POWR TRANSFORMR RMOVAL 1. CARRY OUT 3D CHCKS. 2. Disconnect the wire leads (main wire harness and H.V. wire) from power transformer. 3. Release the lead of the power transformer from the wire holder. 4. Disconnect the lead from magnetron filament. 5. Disconnect the lead of the power transformer from high voltage capacitor. 6. Remove the four (4) screws holding the transformer to bottom plate. 7. Remove the transformer. 18

21 1. CARRY OUT 3D CHCKS 2. Disconnect the leads from the control unit. 3. Remove the one (1) screw holding the control panel to the front plate of the oven cavity. 4. Lift up the control panel and release if from the oven cavity. 5. Now, the control panel assembly is free. NOT: 1. efore attaching a new key sheet, remove 1. CARRY OUT 3D CHCKS. 2. Disconnect the wire leads from magnetron. 3. Remove the four (4) screws holding the magnetron to the waveguide. 4. Remove the magnetron from waveguide. CONTROL PANL RMOVAL MAGNTRON RMOVAL remaining adhesive on the control panel frame surfaces completely with alcohol and so on. 2. When attaching the key sheet to the control panel frame, adjust the upper edge and right edge of the key sheet to the correct position of the control panel frame. 3. Stick the key sheet firmly to the control panel frame by rubbing with soft cloth not to scratch. 5. Now, the magnetron is free. CAUTION: WHN RPLACING TH MAGNTRON, SUR TH R.F. GASKT IS IN PLAC AND TH MAGNTRON MOUNTING SCRWS AR TIGHTND SCURLY. RMOVAL 1. CARRY OUT 3D CHCKS. 2. Disconnect the wire leads from the fan motor and thermal cut-out. 3. Tear the wire holder holding the filament lead of the power transformer and the H.V. wire A. 4. Remove the one (1) screw holding the chassis support to the oven cavity front plate. 5. Push the tab at the end of the chassis support caught on the rear cabinet of the oven cavity. 6. Remove the chassis support by pulling it. 7. Remove the magnetron referring to "MAGNTRON RMOVAL". 8. Remove the one (1) screw holding the air guide to the oven cavity and remove the air guide. 9. Release the snap band of the main wire harness from the light mount plate. 10.Release the filament lead of the power transformer and the H.V. wire A from the fan duct. 11 Release the fan motor assembly from the oven cavity. 12.Remove the one (1) screw from the thermal cut-out angle. 13.Remove the fan blade from the fan motor shaft according the following procedure. 1) Hold the edge of the rotor of the fan motor by using a pair of groove joint pliers. CAUTION: Make sure that any pieces do not enter the gap between the rotor and the stator of the fan motor. ecause the rotor is easy to be shaven by pliers and metal pieces may be produced. Do not touch the pliers to the coil of the fan motor because the coil may be cut or injured. Do not transform the bracket by touching with the pliers. 2) Remove the fan blade assembly from the shaft of the fan motor by pulling and rotating the fan blade with your hand. 3) Now, the fan blade will be free. FAN MOTOR RPLACMNT 19 CAUTION: Do not use this removed fan blade again. ecause the hole(for shaft) of it may become bigger than a standard one. 14. Remove the two (2) screws holding the fan motor to the fan duct. 15. Now, the fan motor is free. Coil Stator Gap racket Rotor Rear view Groove joint pliers Shaft Axis Stator Rotor Side view These are the position where should be pinched with pliers INSTALLATION 1. Install the fan motor to the fan motor angle with the two (2) screws. 2. Install the fan blade to the fan motor shaft according the following procedure. 1) Hold the center of the bracket which supports the shaft of the fan motor on the flat table. 2) Apply the screw lock tight into the hole(for shaft) of the fan blade. 3) Install the fan blade to the shaft of fan motor by pushing the fan blade with a small, light weight, ball peen hammer or rubber mallet.

22 CAUTION: Do not hit the fan blade strongly when installed because the bracket may be transformed. Make sure that the fan blade rotates smooth after installed. Make sure that the axis of the shaft is not slanted. 3. Install the thermal cut-out angle to the fan motor with the one (1) screw. 4. Install the fan motor assembly to the oven cavity by inserting the tabs of the fan duct into the holes of the oven cavity. 5. Re-install the air guide to the oven cavity with the one (1) screw. 6. Re-install the magnetron, together with the fan duct, to the waveguide of the oven cavity with the four (4) screws. 7. Insert the end of the chassis support into the slit of the oven cavity rear cabinet. 8. Re-install the chassis support to the oven cavity front plate with the one (1) screw. 9. Install the main wire harness into the hole of the fan duct and insert the snap band of the main wire harness into the hole of the light mount plate. 10. Install the filament lead and the H.V. wire A into the hole of the fan duct and tie them with the wire holder. 11. Connect the filament lead and the H.V. wire to the magnetron, referring to the pictorial diagram. 12. Connect the wire leads to the fan motor and the thermal cut-out, referring to the pictorial diagram. Table Shaft Center of bracket 1. CARRY OUT 3D CHCKS. 2. Pull the wire leads from the oven lamp socket by pushing the terminal hole of the oven lamp socket with the flat type small screw driver. 3. Tear the cushion from the light mount plate. 4. end the tab of the light mount plate holding the oven. 5. Lift up the oven lamp socket. 6. Now, the oven lamp socket is free. OVN LAMP SOCKT RMOVAL Flat type small screw driver POSITIV LOCK CONNCTOR RMOVAL Oven lamp socket Terminal Wire lead Terminal hole Figure C-1. Oven lamp socket Terminal 1. CARRY OUT 3D CHCKS. 2. Pushing the lever of positive lock connector. 3. Pull out the positive lock connector. Positive lock connector 1 Push CAUTION: When you (Service engineers) connect the positive lock connectors to the terminals, connect the positive lock so that the lever face you (Service engineers). Lever 2 Pull down Figure C-2 Positive lock connector TURNTAL MOTOR RPLACMNT Removal 1. Disconnect the oven from the power supply. 2. Remove the turntable and roller stay from the oven cavity. 3. Turn the oven over. 4. Cut the four (4) bridges holding the turntable motor cover to the bottom plate L with the cutting pliers as shown in Figure C-3 (a). CAUTION: DO NOT DROP TH TURNTAL MOTOR COVR INTO TH OVN AFTR CUTTING TH RIDGS. CAUS IT WILL DAMAG TH WIR LADS OF TH MOTOR AND IT IS DIFFICULT TO RMOV IT OUT OF TH OVN. 5. Remove the turntable motor cover from the bottom plate L. 6. Disconnect the wire leads from the turntable motor. 20

23 7. Remove the single (1) screw holding the turntable motor to the oven cavity. 8. Remove the turntable motor from the oven cavity. 9. Remove the O-ring and washer from the turntable motor. 10.Now, the turntable motor is free. Turntable motor cover ridges ridges Cutting pliers 6. Re-connect the wire leads to the turntable motor. 7. Insert the tab of the turntable motor cover into the hole of the bottom plate as shown in Figure C-3(b). 8. Re-install the turntable motor cover to the bottom plate L with the screw which are removed at the above step 2 as shown in Figure C-3(b). Turntable motor cover Screw: LX-ZA045WR0 Tab Hole ottom plate Screw Figure C-3(a). Turntable Motor Cover Removal Re-install 1. Remove the any sharp edges on the turntable motor cover and the bottom plate L with the cutting pliers. 2. Remove the single (1) screw on the bottom plate as shown in Figure C-3 (a). 3. Re-install the O-ring. 4. Appply the grease (Shinetsu silicone grease G-420 of Sinetsu Chemical Co. Ltd. or Toray Silicone grease SH- 14 of Toray Silicone Co., Ltd.) to the O-ring and the roots of the turntable motor shaft as shown in Figure C Re-install the turntable motor with the O-ring and washer to the oven cavity with the single (1) screw. ottom plate Figure C-3(b). Turntable Motor Cover Re-install Washer O-ring Apply the grease hear Roots of turntable motor shaft Turntable motor Washer O-ring Figure C-4. Washer and O-ring Installation and Grease Applying. Removal 1. CARRY OUT 3D CHCKS. 2. Disconnect the brown wire of the power supply cord from the fuse holder. 3. Cut away the connector (C-230). 4. Remove the single (1) screw holding the green/yellow wire of the power supply cord to the oven cavity. 5. Remove the single (1) screw holding the cord anchorages to the cord angle. 6. Remove the power supply cord from the oven. Re-install 1. Insert the power supply cord into the cord anchorages. 2. Connect the brown wire of power supply cord to the fuse holder correctly. 3. Install the green/yellow wire of power supply cord to the oven cavity with single (1) screw tightly. 4. Make sure that the blue and white wire leads of the power supply cord are stripped for 15mm length from its end. 5. Wind the conductor of the blue and white wires each other. 6. Insert them into the connector (C-230). And clamp it. POWR SUPPLY CORD RPLACMNT lue wire lead of power supply cord 15 mm Wire lead of the main wire harness OVN CAVITY ACK PLAT GRN/YLLOW WIR LU WIR CONNCTOR C-230 WHIT WIR Connector C-230 POWR SUPPLY CORD OVN CAVITY ROWN WIR FUS HOLDR Figure C-5. Power Supply Cord Replacement 21