R-874 (serv.man2). Cautions, general information, servicing warnings, operation sequence and function of components - Sharp Home Appliance Service Manual (repair manual)

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Page

CAUTION, MICROWAVE RADIATION ....................................................................................................   2
GENERAL INFORMATION ....................................................................................................................... 3
SERVICING/WARNING ...........................................................................................................................  3
PRODUCT SPECIFICATIONS ................................................................................................................. 4
APPEARANCE VIEW ..............................................................................................................................  5
OPERATION SEQUENCE ........................................................................................................................ 6
FUNCTION OF IMPORTANT COMPONENTS .......................................................................................  9
TROUBLESHOOTING GUIDE ............................................................................................................... 11
TEST PROCEDURES ...........................................................................................................................  12
TOUCH CONTROL  PANEL ASSEMBLY .............................................................................................. 18
COMPONENT REPLACEMENT AND ADJUSTMENT PROCEDURE ..................................................  24
MICROWAVE MEASUREMENT ...........................................................................................................   30
SCHEMATIC DIAGRAMS ......................................................................................................................  31
PICTORIAL DIAGRAM ..........................................................................................................................  36
POWER UNIT CIRCUIT ......................................................................................................................... 37
CPU UNIT CIRCUIT ............................................................................................................................... 38
PRINTED WIRING BOARD .................................................................................................................... 39
PARTS LIST ..........................................................................................................................................  40
EXPLODED DIAGRAM OF OVEN PARTS ............................................................................................ 43
CONTROL PANEL/DOOR PARTS ......................................................................................................... 44
MISCELLANEOUS/PACKING & ACCESSORIES .................................................................................. 45

S70199R874M//

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

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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.

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 and/ or  Bottom 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.

SERVICING

PRODUCT SPECIFICATIONS

GENERAL INFORMATION

APPEARANCE VIEW

OPERATING SEQUENCE

FUNCTION OF IMPORTANT
COMPONENTS

TROUBLESHOOTING GUIDE
AND TEST PROCEDURE

TOUCH CONTROL PANEL

COMPONENT REPLACEMENT
AND ADJUSTMENT PROCEDURE

MICROWAVE MEASUREMENT

WIRING DIAGRAM

PARTS LIST

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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.

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

GREEN-AND-YELLOW

: EARTH

BLUE

: NEUTRAL

BROWN

: LIVE

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9. Door seals and sealing surfaces
10.Ventilation openings
11.Outer cabinet
12.Power supply cord
13.Turntable
14.Low rack
15.High rack

1. Control panel
2. Oven lamp
3. Grill heating element (Top Grill)
4. Door opening button
5. Waveguide cover
6. Oven cavity
7. Turntable motor shaft
8. Grill heating element

(Bottom Grill)

9

7

10

4

1

8

6

5

3

2

11

12

10

14

15

13

AUTO indicator, showing auto cooking on progress.

DEFROST indicator.

TOP GRILL indicator.

BOTTOM GRILL indicator

CONVECTION indicator.

COOK indicator showing oven in operation.

MICROWAVE indicator.

WEIGHT indicators.

LESS/MORE indicators.

DIGITAL DISPLAY.

INFO indicator for interactive display.

EXPRESS DEFROST keys.

INFO key.

LESS/MORE keys. 

INSTANT COOK keys.

GRILL key.  
Press to select Grill

DUAL CONVECTION/GRILL key.

KITCHEN TIMER/CLOCK SETkey.

START/AUTO MINUTE key.

% percentage microwave power level indicator.

TIME keys. 

STOP/CLEAR key.

WEIGHT CONVERSION key

MICROWAVE POWER LEVEL key.

WEIGHT keys.

CONVECTION 

0

C key.

EXPRESS COOK keys.

MEAL IN ONE keys

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