More challenges with the GE XL1800 - Here we go......
mic was making a winding noise and eventually it stopped heating
I replaced the magnatron tube and life seemed good
now the winding noise remains and the mic will shutdown affter heating for 3 minutes and will reset itself after 10 mins....

any thoughts???? thanks

none.... simply read a number of problen cases with this model and it seemed the M tube was the culprit.

yes to both....

Sorry for the delay...power outage got my computer. Where were we? First, you need to determine where the problem lies. Test to see if the control board is sending 120VAC to the power transformer. Find the primary wires that go from the board to the transformer. Keep your hands and test leads away from the metal of the cabinet and the components from the secondary transformer wires to the capacitor.

Set the controls for a cooking cycle and start the microwave. if you get 120VAC at the transformer, the board is good. If not, replace the contro board. Tell us what you find.

Please remember that very high voltage can remain in the capacitor, even after the oven is off and unplugged. Before sticking tools and hands inside, you should discharge the capacitor by shorting across the terminals. You may get a loud pop accompanied by sparks, or absolutely nothing when you do this.