R-757M (serv.man17). Complete - Sharp Home Appliance Service Manual (repair manual)

R-757M - 1

Page

SERVICING .................................................................................................................. Indside front cover
WARNING MICROWAVE RADIATION .................................................................................................... 3
WARNING ................................................................................................................................................. 3
PRODUCT SPECIFICATIONS ................................................................................................................. 4
GENERAL INFORMATION ....................................................................................................................... 4
APPEARANCE VIEW ..............................................................................................................................  5
OPERATION SEQUENCE ........................................................................................................................ 6
FUNCTION OF IMPORTANT COMPONENTS .......................................................................................  7
TROUBLESHOOTING GUIDE ................................................................................................................. 9
TEST PROCEDURE ............................................................................................................................... 10
TOUCH CONTROL  PANEL ASSEMBLY .............................................................................................. 16
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ..................................................  20
MICROWAVE MEASUREMENT ...........................................................................................................   26
SCHEMATIC DIAGRAMS ......................................................................................................................  27
PICTORIAL DIAGRAM ..........................................................................................................................  29
POWER UNIT DIAGRAM ....................................................................................................................... 30
CONTROL PANEL CIRCUIT DIAGRAM ................................................................................................ 31
PRINTED WIRING BOARD DIAGRAM .................................................................................................. 32
PARTS LIST ..........................................................................................................................................  33
EXPLODED DIAGRAM OF OVEN PARTS ............................................................................................ 35
CONTROL PANEL/DOOR PARTS ......................................................................................................... 36
MISCELLANEOUS/PACKING AND ACCESSORIES ............................................................................. 37

S300330R757M//

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

®

R-757M - 2

1) Disconnect the supply.
2) Door opened, and wedged open.
3) Discharge high voltage capacitor.

The high-voltage capacitor remains charged about 60 sec-
onds 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 High voltage
transformer. Ensure 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 High
voltage transformer.

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 assembly, High voltage harness.

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
power to HIGH and set the microwave timer for two (2) minutes.
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 compo-
nent being tested.

When all service work is completed, and the oven is fully
assembled, the microwave power output should be checked and
a microwave leakage test should be carried out.

R-757M - 3

WARNING

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 absorbing load attached. Never look into an
open waveguide or antenna while the device is energized.

WARNING

Never operate the oven until the following points are ensured.
(A) The door is tightly closed.
(B) The door brackets and hinges are not defective.
(C) The door packing is not damaged.
(D) The door is not deformed or warped.
(E) 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.

Never operate the Grill heater with the oven outer cabinet
removed.  (Because air flow is eliminated, and the excess heat
generated on adjacent components). It can cause permanent
damage or a fire.

®

  R-757(W)M

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.

R-757M - 4

Power Requirements

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

Power Consumption

Microwave cooking

1.42kW Approx. 6.3 A

Grill cooking

1.0 kW Approx. 4.2 A

Dual cooking

2.4 kW Approx. 10.2 A

Power  Output

900 W nominal of RF microwave energy (measured by method of IEC60705))
Operating frequency 2450MHz

Grill heating element Power Output

1000 W

Case Dimensions

Width 520 mm
Height 305 mm (including foot)
Depth 422 mm

Cooking Cavity Dimensions

Width  342 mm
Height 207 mm
Depth 368mm

Turntable diameter

325mm

Control Complement

Touch Control

Clock (1:00 - 12:59 or 0:00 - 23:59)

Timer (0 - 99 minutes 90 seconds)

Microwave Power for Variable Cooking

 Repetition Rate;
100P ................................. Full power throughout the cooking time
70P ..................................................  approx. 70% of FULL Power
50P ..................................................  approx. 50% of FULL Power
30P ..................................................  approx. 30% of FULL Power
10P ..................................................  approx. 10% of FULL Power

TIME key
EXPRESS COOK keys                       WEIGHT CONVERSION key
EXPRESS DEFROST keys                START/AUTO MINUTE key
MEAL IN ONE keys                            STOP/CLEAR key
AUTO COOK key                                KITCHEN TIMER key
GRILL key                                           WEIGHT keys
DUAL GRILL key                                MICROWAVE POWER LEVEL key
LESS/MORE keys                                DELAY START/CLOCK SET key

Net Weight

Approx. 16.5 kg

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

GREEN-AND-YELLOW

: EARTH

BLUE

: NEUTRAL

BROWN

: LIVE