R-795M (serv.man6). Apperance, operation sequence and function of important components - Sharp Home Appliance Service Manual (repair manual). Page 5

R-795M- 

9

The door can be opened by pulling the door handle. When
the handle is pulled, the latch head is pulled, the latch head
is moved upward, and released from the latch hook now
the door can be opened.

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

of the switch must be closed. And the contacts (COM-
NC) must be opened.

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

NO) of the switch must be opened. And the contacts
(COM-NC) must be closed.

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

of the switch must be closed.

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

NO) of switch must be opened.

The monitor switch is activated (the contacts opened) by the
upper latch head on the door while the door is closed. The
switch is intended to render the oven inoperative by means
of blowing the fuse F8A when the contacts of the monitored
latch switch fail to open when the door is opened.
Function
1. When the door is opened, the contacts (COM-NC) of

monitor switch  close (to the ON condition) due to their
being normally closed and contacts (COM-NO) open.
At this time the contacts (COM-NO) of monitored 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 SW3 contacts (COM-NC) are opened and con-
tacts (COM-NO) closed and then contacts (COM-NO)
of monitored latch switch and stop switch are closed.(On
opening the door, each of these switches operate
inversely.)

3. If the door is opened and the monitored latch switch

contacts  (COM-NO) fail to open, the fuse F8A blows
immediately after closing of the monitor switch (COM-
NC) contacts.

CAUTION: BEFORE REPLACING A BLOWN FUSE F8A,

TEST THE MONITORED LATCH SWITCH
AND  MONITOR SWITCH FOR PROPER
OPERATION.  (REFER TO CHAPTER “TEST
PROCEDURE”).

If the wire harness or electrical components are short-
circuited, this fuse blows to prevent an electric shock of 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 the monitored latch switch

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

3. The fuse also blows when the asymmetric rectifier,

H.V. rectifier,H.V. wire harness, H.V. capacitor,
magnetron or secondary winding of high voltage trans-
former is shorted.

T/C transformer converts A.C. line voltage into low voltage
to drive the control unit.

This thermal cut-out protects the magnetron against over-
heat. If the temperature goes up higher than 125˚C be-
cause the fan motor is interrupted or the ventilation open-
ings are blocked, the thermal cut-out will open and line
voltage to the high voltage transformer will cut off and
operation of the magnetron will be stopped. The defec-
tive thermal cut-out must be replaced with a new one.

This thermal cut-out protects the oven against the over-
heat during grill cooking, oven cooking or dual (combina-
tion) cooking. If the temperature rises above 145˚C be-
cause the fan motor is interrupted, the air inlet duct is
blocked or the ventilation openings are obstructed, the
thermal cut-out opens and switches off all the electrical
parts. When the cools itself down to the operating tem-
perature of 115˚C, the contacts of the thermal cut-out will
close again.

The asymmetric rectifier is solid state device that prevents
current flow is both directions. And it prevents the tem-
perature rise of the high voltage transformer by blowing
the fuseF8A when the high voltage rectifier is shorted.

The rated peak reverse voltage of D1 of the asymmetric
rectifier is 6 KV. The rated peak reverse voltage of D2 of
the asymmetric rectifier is 1.7 KV. D1 and D2 of the

asymmetric rectifier or high voltage rectifier are shorted
when the each peak reverse voltage goes beyond the
each rated peak reverse voltage. (The process of the
blowing the fuseF8A.)

Latch hook

Door

SW2: Stop switch

Latch
Heads

SW3: Monitor switch

SW1: Monitored

latch switch

Tab