speed of the probe should not exceed 25mm per second, and the measuring direction should be the same with the outing direction of the probe 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.
5.2.4EXAMINE WHEN THE OVEN AT OPERATING, BUT THE FOOD CAN’T BE HEATED.
(1)Examine when the lamp is on, the glass tray is cycling, the fan operating in normal:
Take off the cabinet, starting the oven, measure the plug of the transformer with an avometer to see whether it is enough to 120V. If it is enough to 120V, then the secondary high voltage of the transformer should be examined as FIG.5 – 3.
Measure it with the
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 plug 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 small. 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 diode then. Measure the diode with R×10K grade of an avometer, the “+” rod end of the avometer connect the cathode of the diode, the
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 small, and near to short circuit, it indicates the high voltage diode has been punctured, and should be replaced by a new one.
If the high voltage diode is OK, then check the forwarding plug
of the transformer to see whether it is enough to 120V. 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 R×1K grade. It is normal if the reading is “0” when at cut off condition. If the reading is “∞”, it indicates the micro switch has broken, and the timer should be replaced by a new one. If all the above examination shows normal ,then check whether the terminal plug of the magnetron and the capacitor have loosened, if it is loosened, pinch it tightly with a pliers.
Fig.5-3
Fig.5-4
Fig.5-5
magnetron
19
