Function Of Imporatnt Components; Medium High, Medium, Medium Low, Low Cooking; Door Open Mechanism; Monitor Switch Sw3 - Sharp R-3A53 Service Manual

R -3A53
R-3A53B
MEDIUM
HIGH, MEDIUM, MEDIUM LOW,
LOW COOKING
When the microwave oven is preset for variable cook-
ing power, 240 volts A.C. power is supplied to the
power transformer intermittently within a 32-second
time base through the relay contact which is coupled
with the current-limiting relay, The following levels of
microwave power are given.
SETTING
32 set ON
HIGH
24 set ON
8 set OFF
MEDIUM HIGH
m-1 Approx 70% = 490 Watts
18 sec. ON
14 set OFF
MEDIUM m-1 .Approx 50% = 350 Watts
12 sec. ON 20 set OFF
MEDIUM LOW J-1 Approx 30% = 210 Watt:
6 set ON 26 set OFF
LOW J] Approx 10% = 70 Watts
NOTE: The ON/OFF time ratio does not exactly corre-
spond to the percentage of microwave power,
because approx. 2 seconds are needed for
heating up the magnetron filament.
FUNCTION OF IMPORTANT COMPONENTS
DOOR OPEN MECHANISM
The door can be opened by pushing the door open
button on the control panel. When the door open
button is pushed, the switch lever is moved upward,
operating the latch head.
The latch head is moved
upward, and released from the latch hook. Now, the
door can be opened.
Door
Latch hook
Latch
head
\
2nd latch switch
Do
1 st latch switch
IST LATCH SWITCH SW1
2ND LATCH SWITCH SW2
STOP SWITCH SW4
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 SW3
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 1 st and 2nd latch switches fail
to open, the fuse M6.3A blows simultaneously with
closing the contacts (COM - NC) of the monitor
switch.
CAUTION: BEFORE REPLACING A BLOWN FUSE F
M6.3A TEST THE IST AND 2ND LATCH
SWITCHES, MONITOR SWITCH AND
MONITOR RESISTOR FOR PROPER OP-
ERATION. (REFER TO CHAPTER "TEST
PROCEDURE".)
MONITOR RESISTOR R 0.8 i2 20W
The monitor resistor prevents the fuse M6.3A bursting
when the fuse M6.3A blows due to the operation of
the monitor switch.
\
Switch lever
Figure D-l. Door Open Mechanism