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Tyler Z.
Tyler Z., Appliance Doc
Category: Appliance
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Experience:  9+ years being an appliance technician with factory training.
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LG microwave, no power, checked all fuses, all good. Replaced

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LG microwave, no power, checked all fuses, all good. Replaced control board, still no power.
Hello, and thank you for using this service. I'll be helping you with your problem today.

So I think you may have missed a fuse if you replaced the control board and you're sure the microwave is getting power. Can you tell me which fuses you tested, their appearance, and their locations approximately?
Customer: replied 4 years ago.

the one on noise filter,the oven themostat,bottom thermostat.

ok, so that bottom thermostat has nothing to do with your problem---that's for turning the fan on if the bottom gets too hot.

There are 3 fuses and it sounds like you checked the noise filter fuse so, that leaves the other two fuses. There should be a small round dime sized device mounted near the magnetron that has 2 wires going to it. That is your magnetron thermal fuse. If it doesn't have continuity, then it needs to be replaced.

The other fuse is located above the microwave cavity so it might require you to uninstall the entire microwave and remove the outer shell to access it. This is also a dime sized black and silver round device with 2 wires going to it. If it's open, then it will need to be replaced.

Since the control board is new, then those are the only things that can really cause this problem if your microwave is getting power from your house.

Customer: replied 4 years ago.

the case is off those 2 you described do have continuity one on top layer between magnitron and noise filter,the other on bottem floor,the blower fan is the mag cooling fan also and sucks air over mag.

No, your misunderstanding what I'm saying.

The one on the bottom floor has nothing to do with this problem. There is a 3rd cavity thermal fuse mounted above the microwave cavity somewhere usually toward the left as you face the unit from the front. It detects if a fire catches inside the microwave oven cavity.

Other than that, the only suggesting I have if it tests good would be to replace the entire noise filter because there is just nothing left if the microwave is definitely getting power.

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