R-90GCK (serv.man17). Complete - Sharp Home Appliance Service Manual (repair manual). Page 9

7

CONVECTION

MOTOR

THERMISTOR

Sensing 

Voltage

ON

OFF

ON

OFF

ON

OFF

0 2 3

28

31

32 (sec.)

64 (sec.)

3 sec.

Sensing the voltage across temperature measurement circuit.

3 sec.

The LSI also stops counting down and closes the
damper door so that no fresh air will enter the oven
cavity.

4. Once the fire sensor feature has shut the unit down, the

programmed cooking cycle may be resumed by
pressing the "START" pad or the unit may be reset by
pressing the "CLEAR" pad.

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

SECONDARY INTERLOCK SWITCH, RELAY
RY2 AND MONITOR SWITCH   FOR PROPER
OPERATION. (REFER TO CHAPTER "TEST
PROCEDURE".)

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.

Monitor switch

Latch hook left

Latch 
head

3rd. latch 
switch

Latch hook right

Latch 
head

Door handle

Secondary
interlock switch
(Monitored latch switch)

Door
sensing switch
(Primary interlock
relay control switch)