Customer Questions and Answers for Magnetron by Whirlpool

Hello Gary. You most likely have a "high voltage" side malfunction. Transformer, diode, magnetron, Capacitor. You will need to be extremely careful if you decide to test the components with a multi meter, Very high residual voltage is present, so make sure you remove power to the microwave and short across the terminals on the capacitor. The magnetron should have a reading of less than 1 ohm resistance across the two terminals, and an "open" circuit between each terminal and chassis ground. The diode/rectifier should have a resistance reading in one direction only, no resistance, or resistance in both directions indicate a faulty diode. The primary winding on the trans former should read approximately 450 Ohms resistance, the secondary winding should read 80 ohms resistance, and the filament transformer should read 100 ohms resistance. If all the readings are proper and in range, replace the magnetron.

Mark, We're sending you some information that will be more helpful. To test a magnetron tube once you've removed power and discharged the capacitor, disconnect the wires and check across the two terminals, you should have less than 1 ohm resistance, and check each terminal to the case, and there should be an "open" (infinite resistance)circuit. The diode/rectifier should read a "closed" circuit in one direction only No "closed" circuit in either direction or a resistance reading other than a closed circuit indicates a faulty diode.