R-2498G (serv.man2). Part 1 Text(1-25) - Sharp Home Appliance Service Manual (repair manual). Page 7

5

COMMERCIAL
FREQUENCY
(50HZ)

POWER OUTPUT
BY MAGNETRON 1

POWER OUTPUT
BY MAGNETRON 2

OPERATION OF
MAGNETRON

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

close (to the ON condition) due to their being normally
closed. At this time the 1st latch switch 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
contacts 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 F6.3A blows simultaneously with
closing of the monitor switch contacts.

CAUTION:BEFORE REPLACING A BLOWN FUSE

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 F6.3A 250V burst-
ing when the fuse 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 fuse 13A blows to prevent an electric shock or
fire hazard.

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

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

2. The fuse also blows when 1st latch switch remains

closed with the oven door open and when the monitor
switch closes.

The asymmetric rectifier is solid state device that pre-
vents current flow is both directions. And it prevents the
temperature rise of the high voltage transformer by blow-
ing the fuse(s) M8A when the high voltage rectifier is
shorted.

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.

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 F6.3A when the
contacts of the 1st latch switch fail to open when the door
is opened.