R-959SLMAA - Sharp Home Appliance Service Manual (repair manual). Page 11

R-959(SL)M-AA

6 – 1

R959(SL)MA

The door can be opened by pushing the open button on the control
panel. When the open button is pushed, the open lever is pushes
lower latch head on the door upward. The upper latch head is linked
with the lower latch head, so now, the door can be opened.

Figure D-1. Door Open Mechanism

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

switch must be closed. And the contacts (COMNC) 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.

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 (con-
tacts open) due to their being normally open contact switches.

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

(COM-NC) are opened and contacts (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 clos-
ing of the monitor switch (COMNC) contacts.

CAUTION: BEFORE REPLACING A NOISE FILTER (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 shortcircuited, this
fuse 20A blows to prevent an electric shock of fire hazard.

1. If the wire harness or electrical components are shortcircuited, 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 con-
tact (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 transformer is shorted.

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

°C

This thermal cut-out protects the magnetron against overheat. If the
temperature goes up higher than 125

°C because the fan motor is

interrupted or the ventilation openings are blocked, the thermal cut-out
will open and switch off all the electrical parts. The defective thermal
cut-out must be replaced with a new one.

°C

This thermal cut-out protects the oven against the overheat during grill
cooking, convection cooking or dual cooking. If the temperature rises
above 170

°C because 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 cut-out cools
itself down to the operating temperature of 155

°C, the contacts of the

thermal cut-out will close again.

°C

This thermal cut-out protects the convection motor against overheat-
ing. If the temperature of the thermal cut-out rises above 170

°C

because the convection fan is interrupted, the ventilation openings are
obstructed or the other abnormal matter occurs, the thermal cut-out
opens and switches off the convection heating element and the other
electrical parts. When the cut-out cools itself down to the operating
temperature of 155

°C, the contacts of the thermal cut-out will close

again.

The asymmetric rectifier is solid state device that prevents current flow
in both directions. And it prevents the temperature rise of the high volt-
age transformer by blowing the fuse F8A when the high voltage recti-
fier is shorted.

Latch hook

Door

Stop switch

Latch

Heads

Monitor switch

Monitored

latch switch

Tab