R-874 (serv.man3). Control pannel assembly, component replacement procedure and leakage measurement - Sharp Home Appliance Service Manual (repair manual). Page 7

R-874M - 24

9. Discharge the H.V. capacitor before carrying out any

further work.

10.Do not operate the oven with the outer case removed.
N.B.; Step 1, 2 and 9 form the basis of the 3D checks.

CAUTION: DISCHARGE HIGH VOLTAGE CAPACI-

TOR BEFORE TOUCHING ANY OVEN
COMPONENT OR WIRING.

CAUTION: WHEN THE OUTER CASE CABINET IS

RE-INSTALLED, INSTALL IT BEFORE THE
BACK PLATE IS INSTALLED, OR THE
OUTER CASE CABINET WILL BE DE-
FORMED.

1. Disconnect oven from power supply.
2. Make sure that a definite “click” can be heard when the

microwave oven door is unlatched. (Hold the door in a
closed position with one hand, then push the door open
button with the other, this causes the latch leads to rise,
it is then possible to hear a “click” as the door switches
operate.)

3. Visually check the door and cavity face plate for dam-

age (dents, cracks, signs of arcing etc.).

Carry out any remedial work that is necessary before
operating the oven.
Do not operate the oven if any of the following conditions
exist;

1. Door does not close firmly.
2. Door hinge, support or latch hook is damaged.
3. The door gasket or seal or damaged.
4. The door is bent or warped.
5. There are defective parts in the door interlock system.
6. There are defective  parts in the microwave generating

and transmission assembly.

7. There is visible damage to the oven.

Do not operate the oven:
1. Without the RF gasket (Magnetron).
2. If the wave guide or oven cavity are not intact.
3. If the door is not closed.
4. If the outer case (cabinet) is not fitted.

Please refer to ‘OVEN PARTS, CABINET PARTS, CONTROL PANEL PARTS, DOOR PARTS’, when carrying out any
of the following removal procedures:

To prevent an electric shock, take the following
manners.
1. Before wiring,

1) Disconnect the power supply.
2) Open the door and wedge the door open.
3) Discharge the high voltage capacitor and wait for

60 seconds.

2. Don't let the wire leads touch to the following parts;

1) High voltage parts:

Magnetron, High voltage transformer, High volt-
age capacitor and High voltage rectifier assem-
bly.

2) Hot parts:

Top heating element, Bottom heating element,

Oven lamp, Magnetron, High voltage transformer
and Oven cavity.

3) Sharp edge:

Bottom plate, Oven cavity, Waveguide flange,
Chassis support and other metallic plate.

4) Movable parts (to prevent a fault)

Fan blade, Fan motor, Switch, Open lever, Open
button,Turntable motor, Convection motor.

3. Do not catch the wire leads in the outer case cabinet.
4. Insert the positive lock connector certainly until its pin

is locked. And make sure that the wire leads should
not  come off even if the wire leads is pulled.

5. To prevent an error function, connect the wire leads

correctly, referring to the Pictorial Diagram.

voltage capacitor.

3. Disconnect the high voltage wire B from the magnetron.
4. Remove one (1) screw holding earth side terminal of

the high voltage rectifier assembly.

To remove the outer case proceed as follows.
1. Disconnect oven from power supply.
2. Open the oven door and wedge it open.
3. Remove the two (2) screws holding the back plate to

the oven cavity rear plate. Remove the back plate

4. Remove the one (1) screw holding the air duct assem-

bly to the oven cavity rear plate.

5. Remove the air duct assembly
6. Remove the eight (8) screws from rear and along the

side edge of case.

7. Slide the entire case back about 3 cm to free it from

retaining clips on the cavity face plate.

8. Lift the entire case from the oven.

To remove the components, proceed as follows.
1. CARRY OUT 3D CHECKS.
2. Disconnect the filament lead of the high voltage trans-

former and the high voltage wire A from the high

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