Sharp R-657W (serv.man5) Service Manual ▷ View online
R657(W)
6 – 1
R657(W)
Service Manual
CHAPTER 6.
FUNCTION OF IMPORTANT COMPONENTS
[1] DOOR OPEN MECHANISM
The door can be opened by pulling the door.
Figure D-1. Door Open Mechanism
[2] MONITORED LATCH 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.
[3] 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
monitored latch switch, the relay RY1 and the relay RY3 fail to
open, fuse F8A blows simultaneously with closing the contacts
(COM - NC) of the monitor switch.
open, fuse F8A blows simultaneously with closing the contacts
(COM - NC) of the monitor switch.
CAUTION: BEFORE REPLACING NOISE FILTER (A BLOWN FUSE
F8A) TEST THE MONITORED LATCH SWITCH, MONI-
TOR SWITCH, RELAY RY1 AND THE RELAY RY3 FOR
PROPER OPERATION. (REFER TO CHAPTER “TEST
PROCEDURE”.)
TOR SWITCH, RELAY RY1 AND THE RELAY RY3 FOR
PROPER OPERATION. (REFER TO CHAPTER “TEST
PROCEDURE”.)
[4] STOP 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.
[5] FUSE 20A
If the wire harness or electrical components are short-circuited, this
fuse 20A blows to prevent an electric shock or fire hazard.
fuse 20A blows to prevent an electric shock or fire hazard.
[6] FUSE F8A (NOISE FILTER)
1. The fuse F8A blows when the contact (COM-NO) of the monitored
latch switch, the relay RY1 and relay RY3 remain closed with the
oven door open and when the monitor switch closes.
oven door open and when the monitor switch closes.
2. The fuse F8A also blows when the H.V. rectifier, H.V. wire harness,
H.V. capacitor, magnetron or secondary winding of high voltage
transformer is shorted.
transformer is shorted.
3. If the wire harness or electrical components are shortcircuited, the
fuse F8A blows to prevent an electric shock or fire hazard.
[7] THERMAL CUT-OUT 145C (OVEN)
The thermal cut-out 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 oven thermal cut-out remains
closed. However, when abnormally high temperatures are reached
within the oven cavity, the oven thermal cut-out will open at 145
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 oven thermal cut-out remains
closed. However, when abnormally high temperatures are reached
within the oven cavity, the oven thermal cut-out will open at 145
°C,
causing the oven to shut down. The defective thermal cut-out must be
replaced with new one.
replaced with new one.
[8] THERMAL CUT-OUT 145C (MG)
This thermal cut-out protects the magnetron against overheat. If the
temperature goes up higher than 145
temperature goes up higher than 145
°C because the fan motor is
interrupted or the ventilation openings are blocked, the thermal cut-out
will open and line voltage to the high voltage transformer will cut off
and operation of the magnetron will be stopped. The defective thermal
cut-out must be replaced with a new one.
will open and line voltage to the high voltage transformer will cut off
and operation of the magnetron will be stopped. The defective thermal
cut-out must be replaced with a new one.
[9] TURNTABLE MOTOR
The turntable motor drives the turntable roller assembly to rotate the
turntable.
turntable.
[10] 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 flows through the oven cavity to remove
steam and vapors given off from the heating foods. It is then vented
through the exhaust air vents at the rear of oven cavity.
air is directed through the air vanes surrounding the magnetron and
cools the magnetron. This air flows through the oven cavity to remove
steam and vapors given off from the heating foods. It is then vented
through the exhaust air vents at the rear of oven cavity.
[11] NOISE FILTER
The noise filter assembly prevents radio frequency interference that
might flow back in the power circuit.
might flow back in the power circuit.
Latch hook
Door
Stop switch
Latch Heads
Monitor switch
Monitored
latch switch
latch switch
Display
