R-2277 - Sharp Home Appliance Service Manual (repair manual). Page 7

5

The monitor switch is activated (the contacts opened) the
upper latch head and switch lever A while the door is
closed. The switch is intended to render the oven inopera-
tive by means of blowing the fuse F2 F6.3A when the
contacts of the 1st latch switch SW1 fail to open when the
door is opened.

Function
1. When the door is opened, the monitor switch SW4

contacts close (to the ON condition) due to their being
normally closed. At this time the 1st latch switch  SW1
is in the OFF condition (contacts open) due to their
being normally open contact switches.

2. As the door goes to a closed position, the monitor

switch contacts are opened and 1st latch switch con-
tacts are closed (On opening the door, each of these
switches operate inversely.)

3. If the door is opened and the 1st latch switch contacts

fail to open, the fuse F2 F6.3A blows simultaneously
with closing of the monitor switch contacts.

CAUTION:BEFORE REPLACING A BLOWN FUSE F2

F6.3A TEST THE 1ST LATCH SWITCH,
MONITOR SWITCH AND MONITOR RESIS-
TOR FOR PROPER OPERATION. (REFER
TO CHAPTER “TEST PROCEDURE”).

The monitor resistor prevents the fuse F2 F6.3A 250V
bursting when the fuse F2 F6.3A 250V 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.

If the wire harness or electrical components make a short-
circuit, this weak point/ Fuse F1 blows to prevent an
electric shock or fire hazard.

1. The door release lever is pulled.
2. The upper latch head is lifted up by the linked door

release lever.

3. The latch lever is lifted up by the door release lever.
4. The joint lever is lifted up by the latch lever.
5. The lower latch head is lifted up by the joint lever.
6. Now both latch heads are lifted up, so they can be

released from the latch hook.

7. Now the door can be opened.

Latch head

Monitor switch

Latch hook

1st. latch switch

2nd. latch switch

Stop switch

3rd. latch switch

Latch head

Joint lever

Door release
lever

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

must be closed.

2. When the oven door is opened, the contacts COM-NO

must be opened.

COMMERCIAL
FREQUENCY
(50HZ)

POWER OUTPUT
BY MAGNETRON 1

POWER OUTPUT
BY MAGNETRON 2

OPERATION OF
MAGNETRON

magnetron can be oscillated alternatively according to the

frequency of the power supply. Refer to the Figure 1 and 2.

T1: HIGH VOLTAGE
      TRANSFORMER

ASYMMETRIC

RECTIFIER

 H. V. RECTIFIER

C1: H.V. CAPACITOR

MG1: MAGNETRON (UPPER)

(REAR)

ASYMMETRIC

RECTIFIER

 H. V. RECTIFIER

C2: H.V. CAPACITOR

MG2: MAGNETRON (LOWER)

T2: HIGH VOLTAGE
      TRANSFORMER

(FRONT)