25
1. High voltage is present at the high voltage terminal of the high voltage transformer during any cooking cycle.
2. It is neither necessary nor advisable to attempt measurement of the high voltage.
3. Before touching any oven components or wiring, always unplug the oven from its power source and discharge
the capacitor (see page 14).
5. Interlock monitor switch
The interlock switch can be checked with an ohmmeter. Isolate the switch and then connect the meter leads to the
common (COM) and normally close (NC) terminals of the switch. The meter should indicate an open circuit with
the door closed and a closed circuit with the door opened.
In case improper operation is indicated, make the necessary switch adjustment or replacement.
6. Primary and secondary interlock switch
The primary and secondary interlock switch can be checked with an ohmmeter. Isolate the switch and connect the
meter leads to the common (COM) and normally open (NO) terminals of the switch.
The meter should indicate an open circuit with the door opened and a closed circuit with the door closed. In case
improper operation is indicated, make the necessary switch adjustment or replacement.
COMPONENT TEST PROCEDURE
1. High voltage transformer
(A) Remove connections from the transformer
terminals and check continuity.
(B) Normal readings should be as follows:
Secondary winding........Approx. 120
Ω
¡
10%
Filament winding ...........................Approx. 0
Ω
Primary winding.............................Approx. 0
Ω
2. High voltage capacitor
(A) Check continuity of capacitor with meter on the
highest OHM scale.
(B) A normal capacitor will show continuity for a short
time, and then indicate 9M
Ω
once the capacitor is
charged.
(C) A shorted capacitor will show continuous
continuity.
(D) An open capacitor will show constant 9M
Ω
.
(E) Resistance between each terminal and chassis
should be infinite.
3. High voltage diode
(A) Isolate the diode from the circuit by disconnecting
the leads.
(B) With the ohmmeter set on the highest resistance
scale, measure the resistance across the diode
terminals.
Reverse the meter leads and again observe the
resistance reading. meter with 6V, 9V or higher
voltage batteries should be used to check the
front-back resistance of the diode, otherwise an
infinite resistance may be read in both directions.
A normal diodes resistance will be infinite in one
direction and several hundred K
Ω
in the other
direction.
4. Magnetron
For complete magnetron diagnosis, refer to
“Measurement of the Microwave Output Power”.
(Page 8) Continuity checks can only indicate and
open filament or a shorted magnetron. To diagnose
for an open filament or shorted magnetron.
(A) Isolate magnetron from the circuit by disconecting
the leads.
(B) A continuity check across magnetron filament
terminals should indicate ohm or less.
(C) A continuity check between each filament terminal
and magnetron case should read open.
