I have a 6 year old GE overstove Spacemaker XL 1800 microwave. Every function works fine on the electronic panel except it does not heat anything up. I have the schematic and flow chart from inside and a multimeter. I think it is the magnetron, but I want to eliminate everything else. Gene

Hello there,

You are right that the problem is from the magnetron, it is defective and need to be tested and replaced. Since you have a multitester, you will be needing a ohm meter, here are the steps to testing and replacing the magnetron.

To test the magnetron, please follow these steps,

NOTE: Before you test this component, make sure your microwave is unplugged, and that you have discharged the capacitors.

There are two tests to conduct in order to determine whether or not a magnetron has become defective. If you receive results other than what are detailed below, you will have to replace your microwave's magnetron. Each test is described for you here:

TEST 1: Locate your magnetron and label each of the wires attached to it so that you know which wires are to be replaced where. Set your ohmmeter to the lowest resistance scale. Take a resistance measurement between each of the magnetron's terminals by touching each probe to one terminal each. Reverse the probes and take a second resistance measurement. Each measurement should read less than one ohm.

TEST 2: Set your ohmmeter to its highest resistance scale. Touch one of the meter's probes to a magnetron terminal. Touch the other probe to the metal magnetron housing. Take special caution to not touch the two probes together. This could result in an inaccurate reading. This test should produce a reading of infinity - indicating an open circuit.

To replace the magnetron

Have a certified and experienced appliance repair technician examine and replace your magnetron. This task is much too dangerous for the average layman to perform on his own

Hope this was helpful you.

All the best

Elect_Comp