everything works but nothing will heat up.
You will want to check the magnetron and the magnetron thermostat. When checking the magnetron, looked for a cracked magnet and do a resistance check which should read less than .5 ohms. The thermostat you would check continuity. No continuity means that it is faulty and needs replaced.
Microwave actually turns on and runs when the door is opened. Lots of helpful answers here suggest replacing three door switches. My question: If I'm willing to buy all three and replace them all, can I do that as an amateur, or does it requires soldering and test equipment?
Answer Hello Tom,
You can certainly do this as an amateur. If you have a Phillips head screwdriver and about 30 minutes, you can do this. Start by unplugging the unit or turning off the breaker. If it is a breaker, verify that the power is off to the unit before proceeding. Remove the two screws along the top edge of the unit and remove the air grille. Now remove the screw centered above the control area. Now lifting and pulling out the control panel will remove it. Be aware that there are wires to this control and if they are removed, you should first take several pictures from different angles to aid in the re-wiring process. Now the door latch assembly containing the door switches is on your left. There should be two screws retaining it. It can now be removed, being careful of the wires. I normally remove the first switch from its' mount and transfer the wires, one at a time to avoid confusion. once the three switches have been replaced and wired, re-assemble in the reverse order of these instructions.
The microwave seems to work its going to the time cycle likes normal operation but no heat. What could be the bad parts? Thanks.
Answer Hello AGB. 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/rectifyer should have a resistance reading in one direction only, no reistance, or resistance in both directions indicate a faulry diode. The primary winding on the trans former should read approximately 450 Ohms resistance, the secondary wonding should read 80 ohms resitance, and the filament transformer should read 100 ohms resistance. If all the readings are proper and in range, replace the magnetron.