Sharp R-212 Service Manual download pdf (Page 7)

R-212B

FUNCTION OF IMPORTANT COMPONENTS

Figure D-1. Door Open Mechanism

1ST. LATCH SWITCH AND 2ND. INTERLOCK RE-

LAY CONTROL SWITCH SWITCH

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.

MONITOR SWITCH

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 1st latch switch and 2nd. interlock relay fail to

open, the fuse blows simultaneously with closing the

contacts (COM-NC) of the monitor switch.

CAUTION: BEFORE REPLACING A FUSE TEST THE

1ST LATCH SWITCH, 2ND. INTERLOCK

RELAY, 2ND. INTERLOCK RELAY CON-

TROL SWITCH, MONITOR SWITCH AND

MONITOR RESISTOR FOR PROPER OP-

ERATION. (REFER TO CHAPTER "TEST

PROCEDURE".)

MONITOR RESISTOR 0.8Ω 20W

The monitor resistor prevents the fuse bursting when

the fuse blows due to the operation of the monitor

switch.

FUSE

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

latch switch and 2nd. interlock relay 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 M6.3A blows to prevent an electric

shock of fire hazard.

HIGH VOLTAGE FUSE

The high voltage fuse blows when the high voltage rectifier

or the magnetron is shorted.

TEMPERATURE FUSE 120˚C (OVEN)

The temp. fuse located on the top of the oven cavity is

designed to prevent damage to the oven if the foods in the

oven catch fire due to over heating produced by improper

setting of cook time or failure of control unit. Under normal

operation, the temp. fuse remains closed. However, when

abnormally high temperatures are reached within the

oven cavity, the temp. fuse will open at 120˚C, causing the

oven to shut down. The defective fuse must be replaced

with a new one.

THERMAL CUT-OUT 95˚C (MAGNETRON )

The thermal cut-out located on the top of the oven cavity

is designed to prevent damage to the magnetron if an over

heated condition develops in the tube due to cooling fan

failure, obstructed air guide, dirty or blocked air intake, etc.

Under normal operation, the thermal cut-out remains

closed. However, when abnormally high temperatures are

reached within the magnetron, the thermal cut-out will

open at 95˚C, causing the oven to shut down. When the

magnetron has cooled to 75˚, the thermal cut-out closes

and cook cycle will resume.

NOISE FILTER

The noise filter prevents the radio frequency interference

that might flow back in the power circuit.

TURNTABLE MOTOR

The turntable motor drives the roller stay to rotate the

turntable.

FAN MOTOR

The fan motor drives a blade which draws external cool air.

This cool air is directed through the air vanes surrounding

the magnetron and cools the magnetron. This air is chan-

nelled through the oven cavity to remove steam and

vapours given off from the heating foods. It is then ex-

hausted through the exhausting air vents at the oven

cavity.

DOOR OPEN MECHANISM

The door is opened by pushing the open button on the

control panel, refer to the Figure D-1.

When the open button is pushed, the open button pushes

the switch lever up and in turn the latch heads are released

from latch hook. When the latch heads are released, the

switch lever returns to its original position by its own

weight.

LATCH HOOK

LATCH

HEADS

DOOR

MONITOR

SWITCH

1ST. LATCH 

SWITCH

2ND. INTERLOCK

RELAY CONTROL 

SWITCH

SWITCH LEVER

1 2 3 4 5 6 7 8 9 10 11 12 ... 35 36

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Sharp R-212 Service Manual Page 7

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