Chapter 6. Function Of Important Compo; Door Open Mechanism; 1St. Latch Switch (Sw1) And 2Nd; Interlock Relay Control Switch (Sw3) - Sharp R-239 Service Manual

CHAPTER 6.
R239(W)
FUNCTION OF IMPORTANT COMPONENTS

[1] DOOR OPEN MECHANISM

The door is opened by pulling the door, refer to the Figure D-1.
Latch Heads
Door
Figure D-1. Door Open Mechanism

[2] 1ST. LATCH SWITCH (SW1) AND 2ND.

INTERLOCK RELAY CONTROL SWITCH
(SW3)
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.

[3] MONITOR SWITCH (SW2)

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 SW1, the relay RY1 and the 2nd. interlock relay RY2
fail to open, the fuse F1 T6.3A blows simultaneously with closing
the contacts (COM-NC) of the monitor switch.
CAUTION: BEFORE REPLACING A FUSE F1 T6.3A TEST THE 1ST.
LATCH SWITCH SW1, RELAY (RY1) AND 2ND. INTER-
LOCK RELAY RY2 AND MONITOR SWITCH SW2 FOR
PROPER OPERATION. (REFER TO CHAPTER "TEST
PROCEDURE".)

[4] FUSE (F1) T6.3A

1. The fuse F1 T6.3A blows when the contacts (COM-NO) of the 1 st.
latch switch SW1, the relay RY1 and the 2nd. interlock relay RY2
remain closed with the oven door open and when the monitor
switch SW2 closes.
2. If the wire harness or electrical components are short-circuited, the
fuse F1 T6.3A blows to prevent an electric shock of fire hazard.

[5] HIGH VOLTAGE FUSE (F2)

The high voltage fuse F2 blows when the high voltage rectifier or the
magnetron is shorted.
Latch Hook
SW3:
2nd. Interlock Relay
Control Switch
SW2:
Monitor Switch
SW1:
1st. Latch Switch
Service Manual

[6] TEMPERATURE FUSE (TF) 150C (OVEN)

The temperature fuse TF 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 temperature fuse
TF remains closed. However, when abnormally high temperatures are
reached within the oven cavity, the temperature fuse TF will open at
150°C, causing the oven to shut down. The defective temperature fuse
TF must be replaced with a new one.

[7] TURNTABLE MOTOR (TTM)

The turntable motor TTM drives the turntable roller assembly to rotate
the turntable.

[8] FAN MOTOR (FM)

The fan motor FM drives a blade which draws external cool air. This
cool air is directed through the air vanes surrounding the magnetron
MG and cools the magnetron MG. This air is channelled through the
oven cavity to remove steam and vapours given off from the heating
foods. It is then exhausted through the exhausting air vents at the
oven cavity.

[9] NOISE FILTER

The noise filter prevents the radio frequency interference that might
flow back in the power circuit.
6 – 1
R239(W)