
Component Testing Procedures
To avoid risk of electrical shock, personal injury, or death, disconnect power to oven and discharge capacitor
before servicing, unless testing requires it.
16500038
July 2012
©2012 ACP, Inc.
2
Illustration
Component
Testing
Results
Thermal Cutout
Disconnect all wires from TCO.
Measure resistance across terminals.
Cavity Thermal Fuse ...................................
Magnetron TCO ...........................................
Open at 219° F (104° C).
Open at 280° F (138° C) and
closed at 180° F (82° C).
Diode Assembly
Discharge Capacitors
Remove diode lead from capacitor and
connect ohmmeter.
Reverse leads for second test.
Infinite resistance in one direction
and 50K
Ω or more in the opposite
direction.
NOTE:
Analog meter must contain a
battery of 6 volts minimum.
MT2
MT1
GA TE
Triac
Disconnect wires to triac.
Measure resistance from:
MT1 to MT2 .................................................
MT1 to Gate ................................................
MT2 to Gate ................................................
All terminals to ground .................................
Caution - Do not operate oven with
wire to terminal MT2 removed.
Infinite.
Approximately 40
Ω or more.
Infinite.
Infinite.
Capacitor Doubler
Discharge Capacitors
Remove wires from capacitor terminals and
connect ohmmeter, set on highest
resistance scale to terminals.
Also check between each terminal and
capacitor case.
Between Terminals:
Meter should
momentarily deflect towards zero
then return to over 5 M
Ω. If no
deflection occurs, or if continuous
deflection occurs, replace capacitor.
Terminal to Case:
Infinite
resistance.
Snubber Assembly
Disconnect wires to snubber.
Measure resistance across terminals.............
Infinite.
Magnetron
Discharge Capacitors
Remove wires from magnetron and connect
ohmmeter to terminals. Also check
between each terminal and ground.
Between Terminals:
Less than 1
Ω.
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.
Blower Motor
Remove all wires from motor.
Measure resistance across coil .......................
Approximately 30
Ω.
Antenna motor
Remove all wires from motor.
Measure resistance across terminals..............
Approximately 3.4 K
Ω.
Wire Harness
Test continuity of wires ................................... Continuity.