Component Testing - Whirlpool WML55011HW Service Manual

COMPONENT TESTING (Cont.)
Unplug microwave oven or disconnect power.
Discharge the high-voltage capacitor and remove the lead wires
from the primary winding of the high-voltage transformer before
conducting any of the following tests.
Remove the lead wires from the related component before
conducting any of the following tests.
All operational checks using microwave energy must be done
with the microwave oven loaded with a minimum of 8 oz
(250 mL) of water in a microwave-safe container.
Components
H.V. Transformer
Filament
(orange/red wires)
Primary
Secondary (white
wire - ground to
transformer case)
Magnetron
H.V. Capacitor
H.V. Diode
Turntable Motor/Open Door Motor
Motor Capacitor
Humidity Sensor PCBA
1
2
3
4
3-6 n Low Profile Microwave Hood Combination
For Service Technician Use Only

Component Testing

IMPOR TANT:
Test/Results
1. Unplug microwave oven or disconnect power.
2. Remove wire leads.
3. Measure resistance:
n Primary winding: Less than 0.5 ohm (approximate)
n Secondary winding: 120 ohms (approximate)
n Filament winding: 0 ohms
n Primary winding to grounding: Normal: Infinite
n Filament winding to grounding: Normal: Infinite
1. Unplug microwave oven or disconnect power.
2. Remove wire leads.
3. Measure resistance:
n Filament terminal: Normal: Less than 1 ohm
n Filament to chassis: Normal: Infinite
1. Unplug microwave oven or disconnect power.
2. Remove wire leads.
3. Measure resistance:
n Terminal to terminal: Normal: Momentarily indicates several ohms, gradually returns
to Infinite
n Terminal to case: Normal: Infinite
NOTE: Some inexpensive meters may indicate infinite resistance in both directions.
1. Unplug microwave oven or disconnect power.
2. Measure resistance:
n Forward: Normal: Continuity
n Reverse: Normal: Infinite
1. Unplug microwave oven or disconnect power.
2. Remove wire leads.
3. Measure resistance:
n Normal: 2.4 k to 3.2 k ohms (approximate)
1. Unplug microwave oven or disconnect power.
2. Remove wire leads.
3. Measure resistance:
n Normal: Momentarily 0 ohms, then goes to Infinite
1. Unplug microwave oven or disconnect power.
2. Remove the 4-pin connector from the cable.
3. Measure resistance across pins 1 and 2.
n Normal: 10 K ohms +/-5% at 77°F (25°C)
4. Measure capacity value across pins 3 and 4.
n Normal: 180 pF +/-5% at 55%RH
Conduct a microwave energy test after performing any tests or
repairs to the microwave oven.
Check that all wire leads are in the correct positions before
operating the microwave oven.
Grasp wire connectors when removing the wire leads from
microwave oven parts.
All testing must be done with an ohmmeter having a sensitivity
of 20,000 ohms per volt DC or greater and powered by at least
a 9 V battery.