R-8000GK - Sharp Home Appliance Service Manual (repair manual). Page 8

6

Monitor switch

Latch hook left

3rd. latch 
switch

Latch 
head

Secondary
interlock switch
(Monitored latch switch)

Door
sensing switch
(Primary interlock
  relay control switch)

Latch hook right

Latch 
head

After cooking is completed, the fan motors will continue for 1
minute. At the end of the cooking cycle, if the cavity air temperature
is above 111˚C, the circuit to RY5 will be maintained (by the

thermistor circuit) to continue operation of the cooling fan motor
until the temperature drops below 90˚C, at which time the relay will
be de-energized, turning off the fan motor.

The door is opened by pulling the door handle down and forward,
referring to the figure D-1. When the door handle is pulled down,
the latch heads are moved upward. And then when the door
handle is pulled forward, the latch heads are released from the
latch hooks right and left. Now, the door will open.

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.

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

be opened.

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

be closed.

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

secondary interlock switch and the relay RY2 fail to open, the
fuse F10A blows simultaneously with closing the contacts
(COM-NC) of the monitor switch .

CAUTION: BEFORE REPLACING A FUSE TEST THE SEC-

ONDARY INTERLOCK SWITCH, RELAY RY2 AND
MONITOR SWITCH   FOR PROPER OPERA-
TION. (REFER TO CHAPTER "TEST PROCE-
DURE".)

1. The fuse F10A blows when the contacts (COM-NO) of the

secondary interlock switch and relay RY2 remain closed with
the oven door open and when the monitor switch   closes.

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

circuited, the fuse F10A blows to prevent an electric shock of
fire hazard.

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

The noise filter prevents the radio frequency interference that
might flow back in the power circuit.

The thermistor is a negative temperature coefficient type. The
temperature in the oven cavity is detected through the resistance
of the thermistor, and then the control unit causes the heater relay
to operate, thus the current to the heating elements is turned ON/
OFF. If the convection cooking or some cooking modes which use
the top / side heating elements is started and the oven temperature
does not rise above 37.8˚C, the control unit will stop the oven after
10 minutes. In this case, the thermistor may be opened.

The temperature fuse located on the waveguide flange is designed
to prevent damage to the magnetron if an over heated condition
develops in the magnetron due to cooling fan failure, obstructed air
guide, dirty or blocked air intake, etc. Under normal operation, the
temperature fuse remains closed. However, when abnormally
high temperatures are reached within the magnetron, the tempera-
ture fuse will open at 150˚C causing the oven to shut down.

The temperature fuse located on the chassis support left is
designed to prevent damage to the chassis support left if an over
heated condition develops in the top and /or side heating
element unit

s due to convection fan failure, thermistor failure,

obstructed air ducts, dirty or blocked air intake, etc.
Under normal operation, the temperature fuse remains closed.
However, when abnormally high temperature are reached within
the top and /or side heating element unit

s, the temperature fuse

will open at 150˚C causing the oven to shut down.

The thermal cut-out located on the thermal cover upper is
designed to prevent damage to the top heating element unit if an
over heated condition develops in the top heating element unit
due to convection fan failure, thermistor failure, obstructed air
ducts, dirty or blocked air intake, etc.
Under normal operation, the thermal cut-out remains closed.
However, when abnormally high temperature are reached within
the top heating element unit, the thermal cut-out will open at
170˚C causing the oven to shut down. When the thermal cut-out
has cooled, the thermal cut-out closes at 155˚C.

The thermal cut-out located on the thermal cover left is designed
to prevent damage to the side heating element unit if an over
heated condition develops in the side heating element unit due
to convection fan failure, thermistor failure, obstructed air ducts,
dirty or blocked air intake, etc.
Under normal operation, the thermal cut-out remains closed.
However, when abnormally high temperature are reached within
the side heating element unit, the thermal cut-out will open at
150˚C causing the oven to shut down. When the thermal cut-out
has cooled, the thermal cut-out closes at 130˚C.

The top heating element is located at the top of the oven cavity.