Sharp Carousel R-990K, Service Manual

R990K(W)

10 – 1

R990K(W)

Service Manual

CHAPTER 10. 

COMPONENT REPLACEMENT AND ADJUSTMENT PROCE-

DURE

[1] BEFORE OPERATING

Microwave ovens contain circuitry capable of producing very high voltage and current, contact with following parts may result in severe, possibly fatal,
electric shock.

(Example)

High Voltage Capacitor, power transformer, Magnetron, High Voltage Rectifier Assembly, High Voltage fuse, High Voltage Harness etc.

WARNING:

Avoid possible exposure to microwave energy. Please follow the instructions below before operating
the oven.

1) Disconnect the power supply cord.

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 damage (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 is 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 trans-

mission 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, DOOR PARTS”, when carrying out any of the following removal procedures:

To prevent an electric shock, take the following precautions.

1. Before wiring, 

1) Disconnect the power supply cord.

2) Open the door and block it 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, Power transformer, High voltage capacitor, High
voltage rectifier assembly and High voltage fuse.

2) Hot parts:

Convection heater, Oven lamp, Magnetron, High voltage trans-
former and Oven cavity.

3) Sharp edge:

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

4) Movable parts (to prevent a fault)

Fan blade, Fan motor, Switch, Switch lever, Open button, Con-
vection motor, Convection fan, Convection fan belt, Pulley, Turn-
table motor, Damper motor, Damper door assembly.

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, refer-

ring to the Pictorial Diagram. 

[2] OUTER CASE REMOVAL

To remove the outer case, procedure as follows.

1. Disconnect the oven from power supply.

2. Open the oven door and wedge it open.

3. Remove the screws from rear and along the side edge of case.

4. Slide the entire case back about 1 inch (3cm) to free it from retain-

ing clips on the cavity face plate.

5. Lift the entire case from the oven.

6. Discharge the H.V. capacitor before carrying out any further work.

7. Do not operate the oven with the outer case removed.

NOTE: Step 1, 2 and 6 form the basis of the 3D checks.

CAUTION: DISCHARGE HIGH VOLTAGE CAPACITOR BEFORE

TOUCHING ANY OVEN COMPONENTS OR WIRING.

WARNING AGAINST HIGH VOLTAGE:

WARNING FOR WIRING

REMEMBER TO CHECK 3D

1) Disconnect the supply.                                                     3)Discharge high voltage capacitor.

2)Door opened, and wedged open.