Whirlpool MH2175XSB Service Guide - Page 39

COMPONENT TESTING Important H.V. Transformer Before testing any of the components, perform the following checks: • Unplug microwave oven or disconnect power. • Remove the lead wires from the related component before conducting any of the following tests. • 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. • 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. • 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. 1. Unplug microwave oven or disconnect power. 2. Remove wire leads. 3. Measure resistance (ohmmeter scale: Rx1): • Primary winding: Less than 0.5 ohm (approximate) • Secondary winding: 80 ohms (approximate) • Filament winding: 0 ohms 4. Measure resistance (ohmmeter scale: Rx1k): • Primary winding to grounding: Normal: Infinite • Filament winding to grounding: Normal: Infinite Filament (black & red) Secondary (white wire, ground to transformer case) Red Tube Black Tube • 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-volt battery White Tube 5-1 Primary (terminals)