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871M - 2

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.

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.

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 QACCBA030WRE0 should be used

Door 

Door hinges 

Grill heating elements 

Oven lamp 

Wave guide cover 

Control panel 

Coupling

Door lock openings 

Grill heating element (Bottom Heater)

Oven cavity

Door seals and sealing surfaces

Safety door latches

Ventilation openings

Outer cabinet

Rear cabinets

Power supply cord

871M - 3

Power Requirements

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

Power Consumption

Microwave cooking

1.55kW Approx. 7.5A

Dual cooking

(Microwave and Top Grill)

2.8kW Approx. 12A

(Microwave and Bottom grill)

2.35kW Approx. 10A

(Microwave and Convection)

2.3kW Approx. 10A

(Top and Bottom Grill)

2.05kW Approx. 9A

Convection cooking

2.08kW Approx. 9.1A

Grill Cooking

(Top Grill)

1.25kW Approx. 5A

(Bottom Grill)

0.85kW Approx. 3.5A

Power Output

900 watts nominal of RF microwave energy (measured by method of IEC
705) Operating fequency 2450 MHz

Grill heating element Power Output

Top Grill 1.2kW (600W x 2)

Bottom Grill 0.8kW

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

WEIGHT keys, INFO key

CONVENIENCE FOODS key

PIZZA key, AUTO COOK key

AUTO DEFROST key, AUTO START key

LESS(

)/MORE(

)

DUAL COOK, GRILL, MICROWAVE, CONVECTION

MINUTE TIMER

CLOCK SETTING, STOP/CLEAR

AUTO MINUTE/START

TIME KEY (10 MIN., 1MIN., 10 SEC.)

Set Weight

Approx. 20 kg

871M - 4

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

IMPORTANT:
When the oven door is closed, the contacts COM-NC of the
monitor switch SW2 must be open and the contacts (COM-
NO) must be closed. When the microwave oven is plugged
in 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.

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

CONNECTED COMPONENTS

RELAY

Oven lamp, Turntable motor

RY1

High voltage transformer

RY2

Fan motor

RY5

1

When the cooking time is up, a signal tone is heard and
the relays RY1 + RY2 + RY5 go back to their home
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
During

Oven Door

Cooking

Open(No cooking)

 Monitored latch Switch COM-NO

Closed

Opened

 Monitor Switch

COM-NO

Closed

Opened

 Monitor Switch

COM-NC

Opened

Closed

Stop switch

COM-NO

Closed

Opened

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 RY5 is
made open. The circuit to the turntable motor is cut off when
the contacts COM-NO of the monitor switch are made open.
The relay RY2 and RY5 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 SW1
and stop switch SW3 must open their contacts (COM-

NO) first. After that the contacts (COM-NC) of the
monitor switch SW2 can be closed and the contacts
(COM-NO) of monitor switch SW2 are made open.

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

of the monitor switch 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 SW1 remain closed, the fuse F2
F8A will blow. Because the relay RY1 and monitor
switch SW2 are closed  and a short circuit is caused.

3 seconds  are needed for heating up the
magnetron filament.

32 sec. ON

24 sec. ON

18 sec. ON

12 sec. ON

6 sec. ON

8 sec. OFF

14 sec. OFF

20 sec. OFF

28 sec. OFF

HIGH

MEDIUM
 HIGH

MEDIUM

MEDIUM 
LOW

LOW

Approx. 70%

Approx. 50%

Approx. 30%

Approx. 10%

Approx. 100%

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 RY2. The following levels of microwave
power are given.

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

the percentage of microwave power, because approx.

Approx 100%

871M - 5

The oven will stop its operation when there is a fire in the
oven cavity in microwave cooking condition.
LSI measures the voltage across the temperature measure-
ment circuit intermittently within a 32-second time base once
the oven is started in the microwave cooking mode. The oven
will stop its operation when the difference of the voltages is
more than 0.69 volts in microwave cooking condition.

1. Within a 32-second base, first the thermistor is energized

for 3 seconds.  After 2 seconds since the thermistor is
energized, the voltage across the temperature
measurement circuit is measured. And after 21 seconds
since the thermistor is cut off, the convection motor
operates for 10 seconds.

2. The oven carries out the procedure above again. If the

second voltage is 0.69V higher than the first voltage, LSI
judges it is a fire in the oven cavity and stops the oven.

3. When sensor cooking, the sensing fire operation is not

carried out until the oven senses the steam from food.
Because food cannot be cooked well by rotating the
convection fan at that time. After sensing the steam, the
sensing fire operation is started.

CONVECTION

MOTOR

THERMISTOR

Sensing 

Voltage

ON

OFF

ON

OFF

ON

OFF

0 2

20

30 32

64 (sec.)

3 sec.

Sensing the voltage across temperature measurement circuit.

4. When LSI judges it is fire in the oven cavity, LSI will switch

off the relays to the power transformer, fan motor and
convection motor and LSI stops counting down. And then
the damper is closed so that the fresh air does not come
into the oven cavity.

The power output of this oven is rated using the method specified by IEC-705.  Full details of how to carry out this
procedure can be found in the Sharp Technical Training notes which is available from Sharp Parts Centre
(part number SERV-LITMW01).

The IEC-705 procedure must be carried out using laboratory-type procedures and equipment.  These requirements
make the procedure unsuitable for routine performance checks.

Note: The following test method gives an indication of the output power only, it cannot be used to establish the actual/

rated output power.  If the true output power is required, then the IEC-705 test method must be used.

Alternative simplified method:
1. Place 2 litres of cold water (between 12

°

C and 20

°

C) in a suitable container.

2. Stir the water and measure the temperature in 

°

C.  Note temperature as T1.

3. Place the container in the microwave and heat the water for 2 minutes on full power.
4. When the 2 minutes is completed, remove the container and stir the water.  Note the water temperature as T2.
5. Calculate the output power using the following formula:

R.F. Power Output = (T2 - T1) x 80.

This oven should be tested for microwave leakage on completion of any repair or adjustment, following the procedure
described in the Sharp Technical Training notes (part number SERV-LITMW01).  The maximum leakage permitted in
BS EN 60335-2-25 is 50W/m

2 

(equivalent to 5mW/cm

2

), however it is not normal to detect any significant leakage,

therefore, any leakage which is detected should be investigated.

It is essential that only leakage detectors with current calibration traceable to the National Physical Laboratories are

used.

Suitable leakage detectors :

CELTEC A100
APOLLO X1