Service manual

3534
MEASUREMENT
1. Microwave Output Power
1-1. Standard Method
Microwave output power can be checked by indirectly
measuring the temperature rise of a certain amount of
water exposed to the microwave as directed below.
1) Microwave power output measurement is made with
the microwave oven supplied at rated voltage and
operated at its maximum microwave power setting
with a load of 1,000¡ 5cc of potable water.
2) The water is contained in a cylindrical borosilicate
glass vessel having a maximum material thickness
of 3 mm and an outside diameter of approximately
190 mm.
3) The oven and the empty vessel are at ambient
temperature prior to the start of the test. The initial
temperature of the water is 10¡ 2¡£c (50¡ 3.6¡£F).
It is measured immediately before the water is
added to the vessel. After addition of the water to
the vessel, the load is immediately placed on the
center of the shelf which is in the lowest normal
position. (Fig. 15).
4) Microwave power is switched on.
5) Heating time should be exactly 47 seconds.
Heating time is measured while the microwave
generator is operating at full power.
The filament heat-up time magnetrons is not
included.
6) The initial and final water temperatures are selected
so that the maximum difference between the
ambient and final water temperatures is 5K.
7) The microwave power output P in watts is calculated
from the following formula:
• ∆T is actual temeprature rise.
• T is the heating time.
The power measured should be 900W¡ 10 %.
2. Electrical Continuity Check of Interlock
Switch
2-1. Procedure
1. Primary Interlock Switch
1) Disconnect two connectors from Primary Interlock
Switch.
2) Connect the ohmeter leads between the terminals of
the primary interlock switch.
3) Read the value of resistance between the terminals
of the switch, when the door is opened, and when
the door is closed.
2. Secondary Interlock Switch
1) Disconnect two connectors from secondary interlock
switch.
2) Connect the ohmeter leads between the terminals of
the secondary interlock switch.
3) Read the value of resistance between the terminals
of the switch, when the door is opened, and when
then oven door is closed.
3. Interlock Monitor Switch
1) Disconnect the lead wire connecting the primary
interlock switch and interlock monitor switch from
primary interlock switch terminal.
2) Connect the ohmeter leads between the lead wire
connector disconnected as item ‘1’ and the power
supply neutral plug pin.
3) Read the value of resistance between the lead wire
connector and the power supply neutral plug pin,
when the oven door is opened, and when the oven
door is closed.
P=4187¡¿∆T/t
Water Load
Tray
Fig. 14
CAUTION :
1. Water load should be measured exactly to 1
litre.
2. Input power voltage should be exactly volts as
specified.
3. Ambient temperature should be 20¡ 2¡£C
NOTE : Remove the power plug from the wall
receptacle before testing.
2-2 Judgement
The value of resistance should be applied to the value
specified below.
When value obtained is not acceptable, the switch
should be replaced or adjusted again.
3. Microwave Leakage Test
3-1. Warning
1) DO NOT place your hands into any suspected
microwave leakage field unless the safe density
level is known.
2) Always start measuring of an unknown field to
assure safety for operating personnel from
microwave energy.
3) Slowly approach the unit under test until the
radiometer reads an appreciable leakage from the
unit under test.
4) Care should be taken not to place the eyes in direct
line with the source of microwave energy.
3-2 Method
The power density of the microwave leakage emitted
by the microwave oven should not exceed 1mW/cm
2
at
any point 50mm (2 in.) or more away from the external
surface of the oven as measured prior to acquisition by
a purchaser and thereafter once the oven is in use,
4mW/cm
2
at any point 50mm(2 in.) or more away from
the external surface of the oven, checks to be made
around the whole of the door seal and on each of the
main unit surface.
Measurements should be made with the oven
operating at its maximum output and containing a load
of 275¡ 15 mililitres of tap water initially at 68¡ 9¡£F
(20¡ 5¡£C) placed within the cavity at the center of the
load carrying surface provided by the manufacture. The
water container should be a low from 600 milliliters
beaker having an inside diameter of approximately
85mm (3-11/32 in.) and made of an electrically
nonconductive material such as glass or plastic.
3-3. Procedures
1) Prepare 600cc glass or plastic container.
2) Pour 275¡ 15 millilitres of tap water initially at 68¡
9¡£F(20¡ 5¡£C) in the container.
3) Place it at the centre of the tray.
4) Operate oven.
5) measure the microwave leakage using an approved
microwave leakage meter after a few minutes of
operation.
Door Open Closed
Primary Interlock Swtich ∞
Secondary Interlock Switch ∞ 0
Interlock Monitor Circuit 0 ∞
NOTE : The scan rate should not exceed 1
inch/sec.
FIG.15
M/W
Lock Auto
cook
Grill Combi Weighf
Defrost
Time
Waff g
Defrost Autocook Grill
Power
More Less
Stop Clear
Clock
Combi
A
A
Auto Cook Menu
T
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W
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Q
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FIG. 16