R-21ATP - Sharp Home Appliance Service Manual (repair manual). Page 7

5

The door is opened by grasping the door handle, refer to
Figure D-1.
When the door handle is grasped, the handle lever is
pulled. And then the upper and lower latch heads are
moved upward by the handle lever, and they are re-
leased from the latch hook. Now the door will open.

1. When the oven door is closed, the contacts (COM-NO)

of each switch must be closed.

2. When the oven door is opened, the contacts (COM-

NO) of each switch must be opened.

1. When the door is closed, the contacts (COM-NC) must

be opened.

2. When the door is opened, the contacts (COM-NC)

must be closed.

3. If the oven door is opened and the contacts (COM-NO)

of the 1st. interlock switch fail to open, the fuse M10A
blows immediately after closing the contacts (COM-
NC) of the monitor switch.

CAUTION: BEFORE REPLACING A BLOWN FUSE

M10A TEST THE 1ST. INTERLOCK SWITCH,
MONITOR SWITCH AND MONITOR RESIS-
TOR FOR PROPER OPERATION.  (REFER
TO CHAPTER “TEST PROCEDURE”).

1. If the wire harness or electrical components are short-

circuited, this fuse blows to prevent an electric shock or
fire hazard.

2. This fuse blows when the 1st. interlock switch remain

closed with the oven door open and when the  contacts
(COM-NC) of monitor switch closes.

The high voltage fuse blows when the high voltage rectifier
or the magnetron is shorted.

This thermal cut-out protects the magnetron against over-
heating. If the temperature goes up higher than 145˚C
because the fan motor is interrupted or the ventilation
openings are blocked, the thermal cut-out  will open and
line voltages to the high voltage transformer will be cut off
and the operation of the magnetron will be stopped. The
thermal cut-out will not resume.

The thermal cut-out located on the top of the oven cavity
is designed to prevent damage to the oven if the food in the
oven catches fire due to over heating produced by im-
proper setting of the cooking time or failure of control unit.
Under  normal operation, the oven thermal cut-out re-
mains closed. However, when abnormally high tempera-
tures are reached within the oven cavity, the oven thermal
cut-out will open at 125˚C causing the oven to shut down.
The thermal cut-out will not resume.

The monitor resistor prevents the fuse M10A bursting
when the fuse M10A blows due to the operation of the
monitor switch.

The noise filter assembly prevents radio frequency inter-
ference that might flow back in the power circuit.

The antenna motor rotates the stirrer antenna located on
the bottom of the oven cavity, so that the food on the
ceramic shelf is cooked evenly during cooking. The an-
tenna motor may turn in either direction.

The cooling fan motor drives a blade which draws exter-
nal cool air. This cool air is directed through the air vanes
surrounding the magnetron and cools the magnetron.
This air is channelled through the oven cavity to remove
steam and vapors given off from the heating food. It is
then exhausted through the exhausting air vents at the
oven cavity.

Latch Hook

Latch Switch

Lever A

Latch Switch

Lever B

Latch Switch

Lever C

Latch Head

Latch Head

Handle

Lever

Door

Handle

Latch

Lever

1st. Interlock Switch

Monitor
Switch

2nd. Interlock Relay 
Control Switch

Latch Switch