Stopped heating, shuts off before time expires

Judging from the model and without looking it up I expect that unit has an inverter. If it is not the Switches and you have replaced the mag, the inverter is the power supply for the mag to work so either mag not getting power from inverter or inverter not getting signals from main PCB Timer board.

We recommend you use the below link to locate an authorized service center. Panasonic microwaves have a 5 year warranty on the microwave.

www.panasonic.com/repair

My microwave has stopped heating up! model # NN-S540BFW PANASONIC ANYONE ELSE HAVING THIS PROBLEM? DO YOU KNOW HOW TO FIX IT?

Hi,
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No sorry the issue will be with eiher the inverter, the magnetron or the main timer board. There is a tracer signal that comunicates through these components and if it doesnt get to where it is supposed to go it wil just shut off, the big hint at that is the time interval. It is not something like a sensor heating up and causing a fault. it is not running long enough to get any thing hot it is in the electroincs. Too expoensive to repair, im sorry better to get a new one. Good Luck

If it stops after 22 seconds, that means the controller has detected a problem, usually a problem with the inverter or a bad magnetron.

Due to the lethal voltages used and produced, I do not recommend that an inexperienced person work on these.

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If it stops at 16 seconds and is a sensor model, it probably has a defective humidity sensor.

You can order Panasonic parts from Tritronics.

If you reconsider, you can find an authorized Panasonic servicer here.

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If it stops at 16 seconds and is a sensor model, it probably has a defective humidity sensor.

You can order Panasonic parts here.

Or you can contact your nearest Panasonic-authorized servicer.

We're happy to help you with free advice and we'd appreciate your thoughtful rating of our answer.

Sounds like the power inverter

my panasonic NN-S561 does exactly the same thing