This is the one appliance repair we ask people not to attempt. Not because it is difficult, but because the component that fails sits next to a capacitor that can hold a fatal charge long after the microwave has been unplugged.
What is happening
Everything you can see is driven by the low-voltage side: the light, the turntable motor, the fan, the display. Heat comes from the magnetron, driven by a high-voltage transformer, a diode and a capacitor. When that circuit fails, the machine looks completely normal and simply produces no heat.
What usually fails
- The magnetron itself, which has a finite life measured in hours of actual cooking.
- The high-voltage diode, which fails far more often than the magnetron and costs a great deal less.
- The capacitor, less commonly, and the component that makes this circuit dangerous.
- A line fuse, on a machine that is completely dead rather than merely cold. A fuse blows for a reason, so replacing it without finding the reason means it blows again.
Repair or replace
On a countertop microwave the honest answer is usually replace. The repair can cost as much as the appliance.
On an over-the-range or a built-in unit the arithmetic reverses completely. The replacement has to fit the existing opening, match the finish of the rest of the kitchen and reuse the ducting, and a diode is a very small fraction of all that. These are worth repairing and we do a lot of them.
The one thing to check yourself
Is it actually on a working socket, and has the breaker tripped? Beyond that, leave the back panel alone.
Call (973) 226-1000 and tell us whether it is a countertop or a built-in unit. That one detail changes the advice we give you before anybody comes out.
