Sharp R-771 OE Service Manual Download Page 7 | Manualshive

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Sharp R-771 OE Service Manual Download Page 7

240V

NOTE : CONDITION

1. DOOR CLOSED

FUSE

UPPER
LATCH

SWITCH

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1

I

I

I

I

I
I

LOWER
LATCH

SWITCH

MAGNETRON
THERM0

CUT-OUT

COOK

TURNTABLE

SWITCH

MOTOR

COOK LAMP

I- -

-

J

I

TIMER

I
I
I

I

SWITCH

L

- - - - - - - - - - -

POWER TRANSFORMER

-

-

-

-

-

-

-

-

I

HIGH

VOLTAGE

r

D,: SHORT PROTECTOR

MAGNETRON

Figure 1. Oven Schematic Off Condition

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Summary of Contents for R-771 OE

Page 1: ...HARf SERVICE MANUAL i KASM482078R S H A R P MICRCIWAVE OVEN R 771 OE In the interests of user safety the set should be restored to its original condition and only parts identical to those specified used ...

Page 2: ...l be qualified to render satisfactory customer service CAUTION MICROWAVE RADIATION Personnel 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 absorb...

Page 3: ...n ll Test Procedures 13 Magnetron Assembly Test 13 Power Transformer Test 14 RectifierTest l 4 High Voltage Capacitor Test 14 Short Protector Test 14 F a n M o t o r T e s t l 5 TimerTest l 5 Magnetron Therm0 Cut out Test 15 Upper Latch Switch Test 15 Lower Latch Switch Test 15 Vari switch Test 15 Vari motor Test 15 Monitor Switch Test 16 CHAPTER IV COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURES ...

Page 4: ...ch Switch Lower Latch Switch and Monitor Switch Adjustment 21 Door Replacement and Adjustment 22 MICROWAVE MEASUREMENT 23 Requirment 2 3 Preparation for The Testing 23 SCHEMATIC DIAGRAM 24 PICTORIAL DIAGRAM 25 PARTS LIST 26 ...

Page 5: ...changing polarity every half cycle the food molecules are changing direction every half cycle or oscil lating back and forth 4 900 000 000 times per second This high speed oscillation causes friction between the mole cules thereby converting the microwave energy to heat ing instructions SPECIFICATIONS Power requirements I Power consumption Microwave output power Case dimensions Width Height Depth ...

Page 6: ... AC is supplied to a primary wind ing of the power transformer through the vari switch 1 3 The power transformer converts 3 4 volts A C output on the filament winding and approximately 2 000 volts AC on the high voltage winding 14 The 3 4 volts A C output from filament winding heats the magnetron tX unent l 5 The 2 000 volts AC output from the secondary winding is sent to a voltage doubler circuit...

Page 7: ...ATCH 01 SWITCH i H I MAGNETRON 1 THERM0 CUT OUT hCOOK TURNTABLE P SWITCH MOTOR 0 COOK LAMP I I I I w L Y J I VARI MOTOR I _ 1 I TIMER I 0 I I 4 I i l VARI I SWITCH L m w POWER TRANSFORMER I I 1 HIGH REC z VOLTAGE r APACITOR I D SHORT PROTECTOR A MAGNETRON Figure 1 Oven Schematic Off Condition 6 ...

Page 8: ... TIMER 5 UPPER LATCH SWITCH MAGNETRON I THERM0 CUT OUT I I Y COOK TURNTABLE ty SWITCH MOTOR I I I I II w 0 J VARI MOTOR _ 1 I TIMER I I I I I L VARI I SWITCH I L _ I POWER TRANSFORMER I II D SHORT MAGNETRON PROTECTOR Figure 2 Oven Schematic Idle Condition 7 ...

Page 9: ...NG CONTROL HIGH 240V 50Hz MONITOR SWITCH TIMER OVEN LAMP CONTACTS UPPER LOWER LATCH LATCH SWITCH SWITCH TURNTABLE MOTOR COOK LAMP r VARI MOTOR 1 POWER TRANSFORMER I l 1 FUSE MlOA MAGNETRON THERM0 CUT OUT COOK I SWITCH I VARI SWITCH I I RT PROTECTOR Figure 3 Oven Schematic Cooking Condition 8 ...

Page 10: ... OFF 20 2 sec Microwave Power Approx 30 ON MED 16 5 Seconds OFF 13 5 sec Microwave Power Approx 50 MED HIGH HIGH ON 23 2 Seconds OFF 6 8 sec Microwave Power Approx 70 ON I Microwave Power 100 b 30 Seconds 4 TIMER Timer switch contacts The timer switch contacts are mechanically opened or closed by turning the timer knob located on the timer motor shaft These contacts control the current path to the...

Page 11: ...oor is closed refer to Figure 5 The switch is intended to render the oven inoperative by means of blowing the fuse when the contacts of the upper latch switch fail to open when the door is opened Functions 1 When the door is opened the monitor switch contacts close to the ON condition due to their being a normally closed At this time the upper latch switch is in the OFF condition contacts open due...

Page 12: ...rom service entrance Open wire in power cord or wire harness Check wall outlet Replace same or repair wiring I I i Blown fuse Check for short circuit and replace fuse I Defective oven lamp I Replace both oven lamps I I I I Defective lower latch switch Procedure J Open or loose wire connection to the above 1 Check wiring I Fan motor does not operate Defective fan motor I Procedure F I Open or loose...

Page 13: ...capacitor Procedure C and E Replace Check wiring Procedure K Procedure A Procedure C Procedure D Oven operates normally when the variable cooking control selector is set at HIGH position but not in any other mode Oven goes into cook cycles but extremely uneven heating is produced in oven load Defective power transformer Procedure B Open or loose wire connection Check wiring Defective vari motor Pr...

Page 14: ...mately P t 4 2 calorie is generated On the other hand if the temperature of the water with V ml rises AT C during this microwave heating period the calorie of the water is V AT The formular is as follows P t 4 2 V AT P 4 2 V AT t ov Our condition for the water load is as follows Water load 2000 ml Heating time 120 seconds 2 minutes pi q Measuring method 1 Put the water load of two 2 litres on the ...

Page 15: ...RECTIFIER TEST DISCHARGE THE HIGH VOLTAGE CAPACITOR BEFORE TOUCHING ANY OVEN COMPONENTS OR WIRING Isolate the rectifier from the circuit Using the highest ohm scale of the meter read the resistance across the terminals and observe reverse the leads to the rectifier terminals and observe meter reading If a short is indicated in both direc tions or if an infinite resistance is read in both direction...

Page 16: ...oor opened and a closed circuit with the door closed In case improper operation is indicated make a necessary switch adjustment or replace the defective switch See adjustment procedure on page 21 J LOWER LATCH SWITCH TEST Isolate the switch and connect the ohmmeter leads to the common COM and normally open NO terminals of the switch The meter should indicate an open circuit with the door opened an...

Page 17: ... 3 d There is a broken door hinge or support energy 3 The door gasket or seal is damaged A Before operating the oven 4 The door is bent or warped 1 Make sure that unlatching the door slowly is ac companied by a click indicating actuation of the latch switches 2 Check visuaI ly the door seal for arcing and dam age B Do not operate the oven until after repair if any of the follwing conditions exist ...

Page 18: ...NG SCREW POWER TRANSFORMER REMOVAL 1 Disconnect the oven power supply and remove the outer case 2 Discharge the high voltage capacitor 3 Disconnect the wire leads from the power transformer 4 Disconnect the filament leads from the magnetron and high voltage capacitor 5 Remove the two 2 screws holding the transformer to the base cabinet A 6 Remove the transformer OVEN LAMP REMOVAL 1 Disconnect the ...

Page 19: ...er case 2 Discharge the high voltage capacitor B to hold the cooling duct A 6 Remove the duct A with the fan motor attached from the unit 3 Disconnect the wire leads from the fan motor 4 Remove the three 3 screws holding the chassis support to the rear cabinet cooling duct A and control panel back plate 5 Release the tab which is provided on the cooling duct 7 Remove the fan blade from the fan mot...

Page 20: ...olding the switch in place LOWER LATCH SWITCH REMOVAL 1 Disconnect the oven from the power supply and remove 5 Remove the single 1 screw and washer holding the the outer case lower latch hook to the oven cavity front flange 2 Discharge the high voltage capacitor 6 Remove the lower latch hook from the flange by moving 3 Remove the complete control panel assembly referring it downward to the Control...

Page 21: ...vari motor shaft 2 Disconnect the wire leads from the vari motor assembly 3 Remove the three 3 screws holding the vari motor assembly to the control panel back plate 4 The vari motor assembly is now free TIMER 1 Remove the timer knob assembly by pulling it off the timer shaft 2 Disconnect the wire leads from the timer motor 3 Remove the two 2 screws holding the timer moun ting plate to the control...

Page 22: ...firmly 4 Now make sure the upper latch switch operation If the upper latch switch has not activated with the door closed loosen the single 1 screw holding the upper latch hook to the oven cavity front flange and adjust the upper latch hook position After the adjustment make sure of the following points 1 The in and out play of the door remains less than OSmm at latched position First check the upp...

Page 23: ... standards Refer to Microwave Measurement Procedure When removing and or loosening hinge such as in the case of a door replacement the following adjustment criteria are taken Door is adjusted to meet the following three conditions by keeping screws of hinge loose 1 Adjust door latch heads at a position where they smoothly catch the latch hooks through the latch holes Refer to upper and lower latch...

Page 24: ... be used for testing Recommended instruments are NARDA 8 100 NARDA 8200 HOLADAY HI 1500 SIMPSON 380M 2 Place the turntable tray into the oven cavity 3 Place the load of 275 rtl5ml of water with the addition of one 1 percent by weight of sodium chloride in solution initialy at 20 5 C in the centre of the over tray The water container should be a low form of 600ml beaker with inside diameter of appr...

Page 25: ...8 SECTIONAL AREA OF 0 75mm NO INDICATION SHOWS 0 5mmz 0 QUICK CONNECT TERMINAL 0 SOLDER OR CLINCH TERMINAL 0 CONNECTOR SW UPPER LATCH SWITCH WHT l t FI FUSE MIOA RED 18 L Lz OVEN LAMP WHT WHT i M FAN MOTOR ORG 18 2 M2 TURNTABLE MOTOR ORG 18 GRywHT NIT WITCH I L3 COOK LAMP mPNK j I M VARI MOTOR RED WHT WHT RN 18 I 1 T POWER i TRANSFORMER Fz OVER CURRENT PROTECTOR 1 HV t MG MAGNETRON I 7 D RECTIFIER...

Page 26: ...22 i i z 0 u Ps 2 5 0 03 v zm u W nwn uu 0 1 I 2 ZII 1 z Y x 2 0 UW A v WI 1 2 P 6 II I 5 b 0 25 ...

Page 27: ... lamp 1 Cook switch 1 Oven lamp 2 Oven lamp socket 2 Fan motor Turntable motor 1 1 Magnetron therm0 cut out 1 Magnetron 1 High voltage capacitor 1 Rectifier 1 Power tr nsformer L 1 Cord corm r 1 Timer 1 Short protector I 1 CABINET PARTS I 1 AS AE AF AG AY AG AH AF AH AW BC AL BQ BA AS BS AF AZ AQ Base cabinet A Base cabinet B Rear cabinet Outer case cabinet Oven lamp access cover Oven lamp cushion...

Page 28: ...mounting plate 1 AC 4 14 LANGQ0254WRwO Oven lamp mounting plate 1 AC 4 15 PDUC 0246WRF0 Magnetron cooling duct A 1 AE 4 16 PDUC 0247WRF0 Magnetron cooling duct B 1 AG 4 17 FDUC OllGWRYO Magnetron duct 1 AE 4 17A PCUSUO323WRPO Magnetron duFt cushion 1 AA 4 18 PCUSU0242YBPO Cooling duct cushion 1 AA 4 19 PDUC 0242WRwO Steam duct 1 AE 4 20 PCUSUO298wRPO Steam cushion 2 AA 4 21 LANGK0141WRFO Upper lat...

Page 29: ...g 1 AA 7 10 LX NZ0031YBEO 1 7 11 Nut lamp access cover mtg AA LX NZ0048WREO Nut magnetron mtg 4 AA 7 12 LX WZ0034WREO 7 13 LX CZ0052WREO Washer square outer case mtg 2 AA Washer outer tooth upper latch hook 2 AA and lower latch 7 14 XWHSD50 08000 hook mtg Washer 1 7 15 actuator mtg AA XWWSD60 08000 Washer outer tooth power transformer 1 AA l Q 7 16 LX BZ0186WREO Screw Rectifier cord mounting brack...

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Page 33: ...DOOR ASSEMBLY x _ MISCELLANEOUS 0 6 4 c 6 5 32 ...

Page 34: ...ust be fixed correctly and firmly 1 The cord anchorage which is used to secure the mains supply cord can be fixed in two different ways 2 if you fix them as shown in Figure 2 the mains supply cord will not be secured firmly 3 Therefore make sure to fix them as shown in figure 1 n 6 MAINS v SUPPLY CORD LSTPP0009Y EFO CORD ANCHORAGE LOWERI 4 mm u CORDANCHORAGE CP UPPER LSTPP0008YBFO Figure 1 Correct...

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