TO PERFORM MICROWAVE LEAKAGE CHECK:
1. Fill 275 milliliters or 9 ounces of tap water
in a 2 cup measuring cup.
2. Place the container in the center of the
oven cavity on the glass tray.
3. Close the door securely.
4. Set power control for microwave “Cook”
(high) or 100% operation. Set timer for 3
minutes and start the oven.
5. Perform the proper adjustment and opera-
tions check with the microwave leakage
meter (refer to the operation instructions
with the meter). Check the oven by moving
the probe, starting at the top right-hand
side of the door, clockwise no faster than
one inch per second, back to the starting
position. Also, a check over the entire visu-
al screen must be made.
Probe Speed: One inch per second (max.)
IMPORTANT:
MICROWAVE LEAKAGE
CHECK MUST BE PERFORMED ON THE
REAR VENTS AND SIDE VENTS.
NOTE:
THE METER PROBE MUST BE
HELD APPROXIMATELY TWO INCHES
FROM THE POINT OF MEASUREMENT. THIS
IS ACCOMPLISHED BY THE USE OF A TWO-
INCH (5 cm) PLASTIC SPACER THAT IS SUP-
PLIED WITH THE METER. IT IS NORMALLY
ATTACHED TO THE PROBE.
6. The maximum allowable microwave leak-
age level is 5mW/cm2 by government stan-
dard. However, the
NEC
standard is 2
mW/
cm2.
IMPORTANT:
IF THE READING IS OVER 2
mW/cm2, REFER TO THE DOOR AND INTER-
LOCK ADJUSTMENTS SECTION IN THIS MAN-
UAL. THE DOOR IS DESIGNED FOR LEAKAGE
OF LESS THAN 1 mW/cm
2
, ADJUSTMENTS
SHOULD BE MADE TO BRING ALL READINGS
TO BELOW 1 mW/cm
2
.
MAGNETRON FAILURE MODES
LOSS OF VACUUM
This is a case where the tube has had the vac-
uum envelope destroyed and air has entered
the tube. This will cause internal arcing. With
continued use, the transformer will eventually
fail and the circuit fuse will blow.
OPERATION FAULTS
OPEN FILAMENTS
A magnetron with an open filament will produce
no heating power.
An open filament lead or “dead” filament trans-
former will give the same indication as an open
filament in the magnetron. This possibility
should be eliminated before the magnetron is
considered open.
INTERNAL PLATE CATHODE SHORT
A shorted magnetron will give the same indica-
tions as the loss of vacuum.
MODING
Moding occurs when the magnetron momentar-
ily operates at a different frequency and a high-
er voltage than designed. Moding results in low
heating power. Moding is usually caused by the
cathode losing emission characteristics.
LOW POWER
Low emission will result in low cooking power.
Food will require a longer than normal cooking
time. It can be detected by a lower than normal
water temperature rise.
LOW EMISSION
Caused by “wearout” of the emission charac-
teristics of the directly heated cathode. The
tube current does not get high enough to cause
the tube to oscillate with normal line voltage.
Everything will appear normal, but the tube will
not heat.
SAFETY PRECAUTIONS FOR DISASSEM-
BLY AND REPAIR
-Cautions to be observed when trou-
bleshooting.
Unlike many other appliances, the microwave
oven is a high-voltage, high-current piece of
equipment. It is completely safe during normal
operation. However, carelessness in servicing
the oven can result in an electric shock or pos-
sible danger from a short circuit.
You are asked to observe the following precau-
tions carefully.
(1) Always remove the power plug from the out-
let before servicing.
(2) Use an insulated screwdriver and wear rub-
ber gloves when servicing the high voltage side.
(3) Discharge the high voltage capacitor before
touching any oven components or wiring.
1.
Check the grounding.
Do not operate on a 2-wire extension
cord. The microwave oven is designed to
be used when grounded. It is imperative,
therefore, to make sure it is grounded
properly before beginning repair work.
2.
Warning about the electric charge in
the high voltage capacitor.
For about 60 seconds after the operation
stops, an electric charge remains in the
high voltage capacitor. When replacing or
checking parts, create a short between
oven chassis and the negative high termi-
nal of the high voltage capacitor, by using
a properly insulated screwdriver to dis-
charge it.
(4) When the
10
Amp. fuse is blown out due
to the operation of the monitor switch,
replace primary and secondary interlock
switches, monitor switch and relay 2.
(5) After repair or replacement of parts, make
sure that the screws are properly tight-
ened, and all electrical connections are
tightened.
(6) Do not operate without cabinet.
DESCRIPTION & FUNCTION OF COM-
PONENTS
FAN MOTOR
The fan motor drives a blower fan which draws
cool air through the back of the oven. This cool
air is directed through the air ducts surrounding
the magnetron tube to cool the magnetron.
Some of the air is then exhausted directly
through the bottom vents.
However, a portion of this air is channeled
through the cavity to remove the steam and
vapors given off from heating food.
OVEN LIGHT
The oven light illuminates the interior of the
cavity so the food can be visually examined
through the door. It is on during microwave
operation only.
POWER TRANSFORMER
The purpose of the power transformer is to pro-
vide the filament voltage for heating the mag-
netron filaments as well as to produce the high
voltage needed for magnetron tube operation.
During a cook cycle, the
230
Volts AC applied
to the primary winding is converted to approxi-
mately 3.
22
Volts AC on the filament winding.
The same
230
Volts AC primary input is con-
verted to approximately
2070
Volts AC on the
high voltage secondary winding of the power
transformer.
CAUTIONS:
AFTER REMOVING THE CABI-
NET, DISCHARGE THE CAPACITOR BY
PLACING AN
INSULATED
SCREWDRIVER
ACROSS THE TERMINALS.
PRIMARY
(UPPER) INTERLOCK
SWITCH
The primary protective switch (interlock) is acti-
vated by the latch when the door is closed. The
switch, in the open position when the door is
open, interrupts the current to the magnetron.
Closing the door will close the interlock switch
and normal operations can be continued.
SECONDARY (LOWER) INTERLOCK
SWITCH
The secondary protective interlock switch is
located behind the front control panel and is acti-
vated when the door is closed. When the door is
open, this switch will interrupt the circuit.
3
Short
