SHARP R84 Service Manual

SERVICE MANUAL

S71101R84STM/

GRILL AND CONVECTION

MICROWAVE OVEN

MODEL

R-84STM

In interests of user-safety the oven should be restored to its original condition and only parts identical to those specified should be used.

TABLE OF CONTENTS

Page

SERVICING ............................................................................................................................................. 2

CAUTION, MICROWAVE RADIATION.................................................................................................... 3

WARNING.................................................................................................................................................3

APPEARANCE ......................................................................................................................................... 4

PRODUCT SPECIFICATIONS .................................................................................................................5

OPERATION SEQUENCE........................................................................................................................6

TEST PROCEDURES ............................................................................................................................. 7

TOUCH CONTROL PANEL ASSEMBLY .............................................................................................. 10

COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE .................................................. 16

MICROWAVE MEASUREMENT ........................................................................................................... 18

SCHEMATIC DIAGRAM ........................................................................................................................ 19

PICTORIAL DIAGRAM .......................................................................................................................... 20

POWER UNIT CIRCUIT DIAGRAM........................................................................................................ 21

CPU UNIT CIRCUIT DIAGRAM.............................................................................................................. 22

PRINTED WIRING BOARD DIAGRAM ..................................................................................................23

PARTS LIST .......................................................................................................................................... 24

EXPLODED DIAGRAM OF OVEN PARTS ............................................................................................ 27

CONTROL PANEL/DOOR PARTS ......................................................................................................... 28

MISCELLANEOUS/PACKING & ACCESSORIES .................................................................................. 29

SHARP CORPORATION

R-84STM - 1

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 capacitor, High voltage transformer, Magnetron, High voltage rectifier, High voltage wires.

REMEMBER TO CHECK

1) Disconnect the supply.

2) Door opened, and wedged open.

3) Discharge high voltage capacitor.

WARNING AGAINST THE CHARGE OF THE HIGH-VOLTAGE 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 highvoltage rectifier) against the chassis using a screwdriver with an insulated handle.

Sharp recommend that wherever possible, fault-finding is carried out with the supply disconnected. In some cases, it may be necessary to connect the supply with the cover removed to carry out fault investigation in the control circuitry. In such cases, the high voltage circuit should be disabled as described below to reduce the hazards:-

• Carry out 3D checks (see above).

• Disconnect the supply leads from the high voltage transformer, making a note of the polarity. Insulate the connectors, ensuring they are positioned away from the transformer and fastened there.

• Connect any relevant test equipment e.g. voltmeter.

• Reconnect the oven to the supply, then close the door.

• Note the results of the test, taking care to keep clear of the operational oven.

• Carry out 3D checks (see above).

• Reconnect the leads to the transformer. Take care to observe correct polarity.

• Carry out 4R checks (see below).

Microwave ovens should not be used without a load. 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 one (1) minute, set the power level to HIGH (100%) and push the start key. When the one (1) minute has elapsed (timer at zero) carefully check that the water is now hot.

AFTER REPAIR REMEMBER TO CHECK 4R

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.

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.

IMPORTANT: If the oven becomes inoperative because of a blown fuse F8A Fuse, check the monitored latch switch

and monitor switch before replacing the fuse F8A.

WARNING: WIRING / RE-WIRING

Before carrying out any work; carry out 3D checks.

1) Disconnect the supply.

2) Open the door and wedge open.

3) Discharge the high voltage capacitor.

RE-WIRING

1) Wires must not touch: a) High voltage parts. b) Parts that become hot. c) Sharp edges. d) Movable parts.

2) Positive lock connectors are fitted correctly

3) Wires are connected correctly as per pictorial diagram.

4) No wire leads are trapped by the outer wrap.

R-84STM - 2

CAUTION / WARNING

CAUTION

MICROWAVE RADIATION

Do not become exposed to radiation from the magnetron or other parts conducting microwave energy. 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.

Servicing and repair work must be carried out only by trained service engineers.

The parts marked '*' on the parts list and schematic diagram have voltages in excess of 250V.

Removal of the outer wrap gives access to potential above 250V.

All the parts marked "∆" on the parts list may cause undue microwave exposure, by themselves, or when they are damaged, loosened or removed.

WARNING

THIS APPLIANCE MUST BE EARTHED

IMPORTANT

THE WIRES IN THIS MAINS LEAD ARE COLOURED IN ACCORDANCE WITH THE FOLLOWING CODE:

GREEN-AND-YELLOW : EARTH BLUE : NEUTRAL BROWN : LIVE

If the mains lead is replaced, only part number QACCBA004URE3 should be used

R-84STM - 3

APPEARANCE VIEW

OVEN

4 3

1. Grill heating element (top grill)

2. Oven lamp

3. Control panel

4. Door opening button

5. Waveguide cover

6. Oven cavity

CONTROL PANEL

7. Turntable motor shaft

8. Grill heating element (bottom grill)

9. Door seals

10. Air-vent openings

11. Outer cabinet

12. Power cord

DIGITALAL DISPLAY

1. MICROWAVE indicator

2. CONVECTION indicator

8 9

3. BOTTOM GRILL indicator

4. TOP GRILL indicator

5. COOK indicator

6. DEFROST indicator

11 12

7. AUTO indicator

8. LESS/MORE indicators

9. INFO indicator

10. MICROWAVE POWER LEVEL percentage

11. WEIGHT indicators

CONTROL PANEL

12. TIME keys

13. INSTANT COOK keys

14. EXPRESS COOK keys

15. EXPRESS DEFROST keys

16. MEAL IN ONE keys

17. CONV. (

C) key

18. DUAL CONV./GRILL key

19. LESS/MORE keys

20. INFO key

21. START/AUTO MINUTE key

22. STOP/CLEAR key

23. KITCHEN TIMER/CLOCK SET key

24. WEIGHT CONVERSION key

25. WEIGHT keys

26. MICRO. POWER key

27. GRILL key

21 22

R-84STM - 4

SPECIFICATION

ITEM DESCRIPTION

Power Requirements 230 - 240 Volts / 50 Hertz / Single phase, 3 wire earthed

Power Consumption Microwave cooking 1.45kW Approx. 6.5A

Dual cooking

(Microwave and Top Grill) 2.4kW Approx. 10.4A

(Microwave and Bottom grill) 1.95kW Approx. 8.5A

(Microwave and Convection) 2.4kW Approx. 10.4A

(Top and Bottom Grill) 1.55kW Approx. 6.3A

Convection cooking 2.08kW Approx. 9.1A

Grill Cooking

(Top Grill) 1.05kW Approx. 4.2A

(Bottom Grill) 0.55kW Approx. 2.3A

Power Output 900 watts nominal of RF microwave energy (measured by method of IEC

60705) Operating fequency 2450 MHz

Grill heating element Power Output Top Grill 1.kW Bottom Grill 0.5kW

Case Dimensions Width 520 mm Height 309 mm (including foot) Depth 488 mm

Cooking Cavity Dimensions Width 349 mm Height 207 mm Depth 357 mm

Turntable diameter 325mm

Control Complement Touch Control System

Microwave Cooking Control

Repetition Rate;

HIGH ............. Full power throughout the cooking time

MEDIUM HIGH ............. approx. 70% of FULL Power

MEDIUM ....................... approx. 50% of FULL Power

MEDIUM LOW .............. approx. 30% of FULL Power

LOW ............................. approx. 10% of FULL Power

TIME keys STOP/CLEAR key

INSTANT COOK keys KITCHEN TIMER/CLOCK SET key

EXPRESS COOK keys WEIGHT CONVERSION key

EXPRESS DEFROST keys WEIGHT keys

MEAL IN

CONV. (

DUAL CONV./GRILL key

LESS(

INFO keys

START/AUTO MINUTE key

ONE keys MICRO. POWER key

C) key GRILL key

)/MORE( ) keys

Net Weight Approx. 20 kg

As part of our policy of continuous improvement, we reserve the right to alter design and specifications without notice

Note: Temperature measurements taken whilst the oven is in convection mode will differ from the displayed level. This is due to the grill elements turning on and off in order to regulate the oven temperature. This will not affect the cooking results as long as the operation manual and cook book are followed correctly.

R-84STM - 5

OPERATION SEQUENCE

OFF CONDITION

Closing the oven door activates all door interlock switches (monitored latch switch and stop switch).

IMPORTANT: When the oven door is closed, the contacts monitor switch

SW2 must be open and the contacts (COM-

COM-NC of the

NO) must be closed. When the microwave oven is plugged into a wall outlet (230-240V / 50Hz), 230-240 volts A.C. is supplied to the point

A1 + A3 in the control unit.

1. The display starts demo mode.

2. To set any programmes or set the clock, you must first touch the STOP key.

3. Information appears on display.

NOTE: When the oven door is opened, the oven lamp

comes on at this time.

MICROWAVE COOKING CONDITION

HIGH COOKING

Enter a desired cooking time with the Time keys and start the oven with touching START key.

Function sequence Figure O-1 on page 18

CONNECTED COMPONENTS RELAY Oven lamp, Turntable motor RY1 High voltage transformer RY2 Fan motor RY6

1 When the cooking time is up, a signal tone is heard and

the relays position. The circuits to the oven lamp, high voltage transformer, fan motor and turntable motor are cut off.

2. When the oven door is opened during a cooking cycle, the switches come to the following condition.

Switch Contact Condition

Monitored latch Switch COM-NO Closed Opened Monitor Switch COM-NO Closed Opened Monitor Switch COM-NC Opened Closed Stop switch

RY1 + RY2 + RY6 go back to their home

During Oven Door Cooking Open(No cooking)

COM-NO Closed Opened

NO) first. After that the contacts (COM-NC) of the monitor switch (

COM-NO) of monitor switch SW2 are made open.

3-2. When the oven door is closed. The contacts (

of the monitor switch

SW2 can be closed and the contacts

COM-NC)

SW2 must be opened and the contacts (COM-NO) of monitor switch SW2 must be closed. After that the contacts of the monitored latch switch

SW1 and the stop switch SW3 are made closed.

3-3. When the oven door is opened and the contacts of the

monitored latch switch F8A will blow. Because the relay

SW1 remain closed, the fuse F2

RY1 and monitor

switch SW2 are closed and a short circuit is caused.

MEDIUM HIGH, MEDIUM, MEDIUM LOW, LOW

COOKING

When the microwave oven is preset for variable cooking power, the 230-240 volts A.C. power is supplied to the high voltage transformer intermittently within a 32-second time base through the relay contact which is coupled with the current-limiting relay power are given.

Note: The On/Off time ratio does not exactly correspond to

the percentage of microwave power, because

3 seconds are needed for heating up the magnetron filament.

RY2. The following levels of microwave

32 sec. ON

HIGH

MEDIUM HIGH

MEDIUM

MEDIUM LOW

LOW

24 sec. ON

18 sec. ON

12 sec. ON

6 sec. ON

8 sec. OFF

14 sec. OFF

20 sec. OFF

28 sec. OFF

approx.

Approx 100%

Approx. 100%

Approx. 70%

Approx. 50%

Approx. 30%

Approx. 10%

The circuit to the high voltage transformer, is cut off when the contact of relay

RY2 contacts COM-NO of the monitored latch switch SW1, and monitor switch SW2 are made open. The circuit to the fan motor is cut off when the relay

RY6 is made open. The circuit to the turntable motor is cut off when the contacts The relay

COM-NO of the monitor switch are made open.

RY2 and RY6 are made open when the door is opened. 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 remaining

time.

3. MONITOR SWITCH CIRCUIT

The monitor switch

SW2 is mechanically controlled by the oven door, and monitors the operation of the monitored latch switch

SW1.

3-1. When the oven door is opened during or after the cycle

of a cooking program, the monitored latch switch and stop switch

SW3 must open their contacts (COM-

SW1

R-84STM - 6

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