primary
winding
transformer
Place a graduate of 275ml water at the middle of the
glass
tray
of the oven (FIG.5 - 1).
Close
the door, power set high,
time
set
to 3
minutes,
press the
starting
button
to operate the oven.
After
rectified the microwave leakage
measure,
measure around the
door crack, those hole position of the window and the air vent at
four sides of the oven with the próbę of the measure. When
measure,
the moving speed of the próbę should not exceed
25mm per second, and the measuring direction should be the
same with the outing direction of the próbę should not exceed
25mm per second, and the measuring direction should be the
same with the outing direction of the
microwave
leakage (FIG.5 -
2)..
When measuring the ultimate value of microwave leakage of all the measure position should not exceed 1
milliwatt/cm2,
of should be considered as abnormal.
5.2.4
EXAMINE
WHEN THE OVEN AT
OPERATING,
BUT THE FOOD
CANT
BE HEATED.
(1) Examine when the lamp is on, the glass tray is cycling, the
Fig.
5-3
fan operating
in
normal:
Take
off
the cabinet, starting the oven, measure the
pług
of the
transformer with an avometer to see whether it is enough to
220V.
If
it is enough to 220V, then the
secondary
high voltage of
the transformer should be examined as FIG.5 - 3.
Measure it with the 2500V-alternating grade of model 500
avometer. One rod of the avometer connects the iron
córę
of the
transformer, the other rod connects the secondary high voltage
pług
(FIG.5 - 4). The avometer reading should be about
2100V
(when measure, be careful with the high voltage). If no voltage
at all, it indicates that the transformer has broken, and should be
replaced by a new one. If it is enough to
2100V,
then check the
filament voltage of the transformer with alternating
10V
grade of
an
avometer,
the value should be about 3.4V (FIG.5 - 5).
If there is no voltage at all, it indicates the transformer has
broken, and should be replaced by a new one. If it is enough to
3.4V, check the filament resistance of the magnetron, measure
the filament
pług
with the
R*1
grade of a avometer (FIG.5 - 6). If
it is open -
circuited,
it indicates the magnetron has broken, and
should be replaced by a new one. It is normal if the resistance
very
smali. Then check whether the magnetron
steel
has broken,
if broken, replace with a new magnetron.
If there is no problem with the
magnetron,
check the high
voltage diodę then. Measure the diodę with
RxiOK
grade of an
avometer, the
"+"
rod end of the avometer connect the cathode
of the diodę, the
"-"
rod end of the avometer connect the anodę
of
the diodę
(FIG.5-7).
The avometer reading should be about 150 thousand ohms.
The change the rod to
different
electrode, the reading should be
"°°"
. If the reading is
very
smali, and near to
short
circuit,
it
indicates the high voltage diodę has been punctured, and
should be replaced by a new one.
If the high voltage diodę is
OK,
then check the
forwarding
pług
of the transformer to see whether it is enough to 220V. If it is not
enough, check the
micro
- switch of the time and power
distributor. Connect the two rods of the avometer to the 1,2 place
of the timer with
RxiK
grade. It is normal if the reading is "O"
when at cut off condition. If the reading is
"°°"
, it indicates the
11
transformer
secondary winding
Fig. 5-4
filament
wingding
Fig. 5-5
magnetron
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