R-202M - Sharp Home Appliance Service Manual (repair manual)

202M - 1

R

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

Page

SERVICING ......................................................................................................................................  2
CAUTION, MICROWAVE RADIATION .............................................................................................  3
WARNING .........................................................................................................................................  3
PRODUCT DESCRIPTION ...............................................................................................................  3
OPERATION DATA ..........................................................................................................................  4
DOOR SWITCHES ...........................................................................................................................  4
OUTPUT POWER TEST PROCEDURE ...........................................................................................  5
COMPONENT REPLACEMENT .......................................................................................................  5
MICROWAVE LEAKAGE...................................................................................................................  7
WIRING / RE-WIRING........................................................................................................................ 8
SCHEMATIC DIAGRAM ...................................................................................................................  9
WIRING DIAGRAM ...........................................................................................................................  10
PARTS LIST ......................................................................................................................................  11
EXPLODED ILLUSTRATION ............................................................................................................  13

R-202

TIMER

O

.5

1.

1.O

1.5

1.5

2.2.

O

O

COOK & DEFROST
GUIDE            (KG)

1O

5

O

15

2O

25

3O

MED LOW

DEFROST

COOK

MED

COOKING CONTROL

WITH COOK & DEFROST GUIDE

MED HIGH

HIGH

LOW

R-202M

202M - 2

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.

1)

econnect all leads removed from components during testing.

2)

eplace the outer case (cabinet).

3)

econnect the supply.

4)

un 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 F1 in the monitored latch switch - monitor
switch circuit, check the monitored latch switch and monitor switch before replacing the fuse F1.

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 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.

1)

isconnect the supply.

2)

oor opened, and wedged open.

3)

ischarge 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
high-voltage rectifier) against the chassis using a screwdriver with an insulated handle.

202M - 3

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 en-
ergy.  All input and output microwave connections,
waveguides, flanges and gaskets must be secured.
Never operate the device without a microwave en-
ergy absorbing load attached. Never look into an
open waveguide or antenna while the device is ener-
gized.

Power Requirements

230 -240 Volts     50 Hertz     Single phase, 3 wire grounded

Power Consumption

1.24KW

Power Output

800 watts nominal of RF microwave energy (measured by way of IEC 705)
Operating frequency of 2450 MHz

Case Dimensions

Width 449 mm     Height 282 mm including foot     Depth 385 mm

Cooking Cavity Dimensions

Width 287 mm     Height 220 mm     Depth 311 mm

Turntable diameter

272 mm

Control Complement

Mechanical Control System

Microwave Power for Variable Cooking

     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

Set Weight

Approx. 13.3 kg

 

  

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 QACCBA030WRE2 should be used

202M - 4

Closing the door activates all door interlock switches (moni-
tored latch switch and latch switch).

IMPORTANT
When the timer knob is at "0" the oven is in the OFF
condition.

Approx. 10% = 80 Watts

26 sec. ON

4 sec. ON

8 sec. ON

14 sec. ON

20 sec. ON

22 sec. OFF

18 sec. OFF

12 sec. OFF

6 sec. OFF

LOW

MEDIUM HIGH

MEDIUM

MEDIUM LOW

HIGH

Approx. 70% = 560 Watts

Approx. 50% = 400 Watts

Approx. 30% = 240 Watts

Approx. 100% = 800 Watts

When the microwave oven is preset for variable cooking
power, the line voltage is supplied to the power transformer
intermittently within a 26-second time base through the
relay contact which is coupled with the current-limiting relay
(RY2). The following levels of microwave power are given.
SETTING

NOTE: The ON/OFF time ratio does not exactly correspond

to the percentage of microwave power, because
approx. 3 seconds are needed for heating up the
magnetron filament.

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.

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 monitored latch switch (SW3) fail to open, the fuse
F1 blows simultaneously with closing the contacts (COM
- NC) of the monitor switch (SW2).

CAUTION: BEFORE REPLACING A BLOWN FUSE (F)

F1 TEST THE MONITORED LATCH SWITCH
(SW3), + MONITOR SWITCH (SW2) FOR
PROPER OPERATION.

Latch hook

SW3: Monitored
          Latch switch

Door

SW2: Monitor switch

SW1: Latch switch

Latch heads