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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 power.
Illustration
Filter Assembly
May 2019
©2019 ACP, Inc.
Component
Thermal Cutout
Disconnect all wires from TCO.
Measure resistance across terminals.
Cavity TCO..................................................
Magnetron TCO ..............................................
Diode/Rectifier
Discharge Capacitor
Remove diode lead from capacitor and
connect ohmmeter.
Reverse leads for second test.
Capacitor
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.
Magnetron
Discharge Capacitor
Remove wires from magnetron and
connect ohmmeter to terminals. Also check
between each terminal and ground.
Stirrer Motor
Remove all wires from terminals.
Measure resistance from:
terminal to terminal......................................
Blower Motor
Remove all wires from motor.
Measure resistance from terminal to
terminal... .......................................................
Fuse Block
Power In terminals .......................................
Power Out terminals ....................................
Fuse...................................................
Test
Open at 203° F (95° C) Closes at 185°
F (85° C)
Open at 293° F (145° C) Closes at 275°
F (135° C)
Infinite resistance should be measured in
one direction and 50KΩ or more in the
opposite direction.
NOTE: Test meter must contain a
battery of 6 volts minimum.
1.05uf
Between Terminals: Meter should
momentarily deflect towards zero then
return to over 5 MΩ. If no deflection
occurs, or if continuous deflection
occurs, replace capacitor.
Terminal to Case: Infinite resistance.
2M248(J)A-B2
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.
120vac 60hz 35RPM
Bidirectional
Approximately 4K Ω.
Approximately 45 Ω.
120vac
120vac
If no power in, check power outlet If
no power out, check fuse
Rated 20A Fuse 250vac
Results
16500067
Rev 2
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