We have a Goldstar GMS 1124TW and it has stopped heating, everthing else works.

Hello there
Whenever you have a no heat situation in your microwave this is due to the megnetron being faulty and needing replacement
i will give you the full procedure to test and replace if needed

The following resistance tests will conclusively reveal a magnetron that is shorted or one that has an open filament winding.
test 1

1. unplug the oven make sure the oven is completely disconnected from any power source
2. discharge all power from the capacitors.
3. Carefully remove all leads from the magnetron terminals. Proper wiring is important so make notes of the wire locations.
4. Set the ohmmeter to its lowest resistance scale.
5. Measure the resistance from one magnetron terminal to the other in either direction.
6. The magnetron filament resistance should be less than one ohm. If this test fails read my next post on replacement


Test 2

1. With the meter set to the highest resistance scale, check from the magnetron terminals to the metal magnetron housing. (Be careful not to touch the meter leads as this will result in a false reading).
2. The meter should read infinity (open circuit) regardless of meter polarity.
3. Even a slight reading would indicate a defective magnetron.

replace the old

remove the wire that attach to the magnetron and mark to identify where they go
unscrew the screws that hold it in place and remove

1. Be careful not to strike or touch the antenna dome area
2. Be sure to transfer any add-on parts, such as an air duct or thermal fuse
3. Insure that the wire mesh rf gasket is intact and in place
4. Examine the rim of the opening where the magnetron dome is to be inserted into the waveguide. smooth out any irregularities, such as dents, pits, and burns. the rim surface should be bare metal, smooth to the touch. use light-grade sandpaper do not use steel wool.
5. If there is evidence of poor terminal connections i.e., discolored, burned, pitted connectors), repair or replace the slip-on connectors on the filament leads
6. install the new one and replace the screws and wires and marked then plug in the microwave and test