Microwave Measurement - Sharp R-990C Service Manual

2 LIFT UP
PUTTY KNIFE
1 BENT
CHOKE COVER
Figure C-2. Door Disassembly
DOOR PANEL
5. Remove the eleven (11) screws holding the door panel
to the door frame.
NOTE: The one (1) screw of the eleven (11) screws also
holds the earth terminal of the door decoration to
the door frame.
After adjustment of door latch switches, monitor switch
and door are completed individually or collectively, the
following leakage test must be performed with a survey
instrument and it must be confirmed that the result meets
the requirements of the performance standard for micro-
wave oven.
REQUIREMENT
The safety switch must prevent microwave radiation emis-
sion in excess of 5mW/cm
external surface of the oven.
PREPARATION FOR TESTING:
Before beginning the actual test for leakage, proceed as
follows;
1. Make sure that the test instrument is operating normally
as specified in its instruction booklet.
Important:
Survey instruments that comply with the requirement
for instrumentations as prescribed by the performance
standard for microwave ovens must be used for testing.
2
mW cm
2
mW cm
Bent
INSIDE
Door Choke
Panel
cover
Upper
Lower
FRONT

MICROWAVE MEASUREMENT

2 at any point 5cm or more from
Microwave leakage measurement at 5 cm distance
6. Remove the door panel from the door frame. Now the
door panel is free.
DOOR GLASS
7. Remove the two (2) screws holding the thermal plate U
to the door frame.
8. Remove the two (2) screws holding the thermal plate R
to the door frame.
9. Remove the thermal plate U and the thermal plate R
from the door frame.
10.Slide the door glass leftward.
11.Slide the door glass upward.
12.Remove the door glass from the door frame. Now the
door glass is free.
DOOR DECORATION AND DOOR FRAME
13.Straighten all tabs of the door decoration.
14.Remove the door decoration from the door frame.
15.Now the door decoration and door frame are free.
Recommended instruments are:
NARDA 8100
NARDA 8200
HOLADAY HI 1500
SIMPSON 380M
2. Place the oven tray into the oven cavity.
3. Place the load of 275
5˚C in the centre of the oven tray. The water
container should be a low form of 600 ml beaker with
inside diameter of approx. 8.5cm and made of an
electrically non-conductive material such as glass
or plastic.
The placing of this standard load in the oven is important
not only to protect the oven, but also to insure that any
leakage is measured accurately.
4. Close the door and turn the oven ON with the timer set
for several minutes. If the water begins to boil before
the survey is completed, replace it with 275ml of cool
water.
5. Move the probe slowly (not faster that 2.5cm/sec.)
along the gap.
6. The microwave radiation emission should be measured
at any point of 5cm or more from the external surface
of the oven.
31
R-990C(S)
15ml of water initially at 20