LG Microwave Repair

Repairing an LG microwave starts with knowing which design you have. Over-the-range models, including ExtendaVent and convection versions, double as the range hood with a vent fan, lights and grease filters. Countertop models such as the NeoChef line often use an inverter: instead of a heavy transformer cycling on and off, an inverter board feeds the magnetron steady, adjustable power.

Running without heating is the failure that matters most. On a conventional transformer model the suspects are the magnetron, high-voltage diode, capacitor and fuse. On an inverter model the inverter board itself is a prime suspect, and it is a pricier part. A loud hum or buzz while cooking often points to a failing magnetron or high-voltage component, and the fix depends entirely on which design is inside.

Other faults are less dramatic. A failed door switch can blow the main fuse and leave the unit completely dead. On over-the-range units, touch pads give up after years of steam rising from the cooktop, and vent motors loaded with grease grind or stall. A vent fan that switches itself on is usually the heat sensor protecting the electronics from a hot cooktop below, which is normal.

Owner checks stop at the outside of the cabinet: the outlet, the breaker, clean grease filters and a turntable seated on its coupler. Do not take the cover off. The capacitor and the inverter board can hold dangerous voltage after unplugging. Visible arcing usually comes from a burned waveguide cover or metal in the cavity, so stop using the unit until it is checked.

We discharge the high-voltage circuit, then test the magnetron, diode, capacitor and transformer or the inverter board, along with the door switches and fuse. Over-the-range units also get a vent motor check and a look at the mounting, since a sagging unit pulls the door out of line. Those are usually worth repairing; a countertop model with a dead magnetron or inverter board often is not.