Testing Procedures
To avoid risk of electrical shock, personal injury or death; disconnect power to oven and discharge capacitor
before servicing, unless testing requires power.
Illustration
Thermal cutout
Diode
Circuit Protector
Capacitor
Magnetron
Blower motor
Stirrer motor
Transformer
Secondary
Filament
Primary
Lamp receptacle
Wire Harness
20
!
Component
Disconnect all wires from TCO.
Measure resistance across terminals.
Cavity TCO............................................
Magnetron TCO.....................................
Discharge Capacitor
Remove diode lead from capacitor and
connect ohmmeter.
Reverse leads for second test.
Discharge Capacitor
Remove diode lead from capacitor and
connect ohmmeter.
Reverse leads for second test.
Discharge Capacitor
Remove wires from capacitor terminals
and connect ohmmeter, set on highest
resistance scale to terminals.
Also check between each terminal and
capacitor case.
Discharge Capacitor
Remove wires from magnetron and
connect ohmmeter to terminals. Also
check between each terminal and
ground.
Remove all wires from motor.
Measure resistance across coil .............
Remove all wires from motor.
Measure resistance across terminals ....
Discharge Capacitor
Remove all wires from terminals.
Measure resistance from:
Primary ................................................
Filament ...............................................
Secondary to Ground screw on
transformer stack .................................
Test continuity of receptacle terminals.
Test continuity of wires
16026795
WARNING
Testing
Results
Closed at 32 F (0 C) and
Opens at 230 F (110 C)
Closed at 140 F (60 C) and
Opens at 320 F (160 C)
Infinite resistance should be
measured in one direction and 50K
or more in the opposite direction.
NOTE: Ohmmeter must contain a
battery of 6 volts minimum.
Infinite resistance should be
measured in one direction and 50K
or more in the opposite direction.
NOTE: Ohmmeter must contain a
battery of 6 volts minimum.
Between Terminals: Meter should
momentarily deflect towards zero
then return to over 5 M . If no
deflection occurs, or if continuous
deflection occurs, replace capacitor.
Terminal to Case: Infinite resistance
Between Terminals: Less than 1
Each terminal to ground measures
Infinite resistance.
Note: This test is not conclusive. If
oven does not heat and all other
components test good replace the
magnetron and retest.
Approximately 31 – 35
Approximately 12 – 14 K
Less than <1
Less than <1
Approximately 70 – 80
Indicates continuity with bulb
installed.
Indicates continuity
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