No power, not even clock. Previossly Fan was working poorly and then microwave would work for a week and then stop working.

Most likely door switches. Companies these days use switches with small 3/16 terminals and they tend to get hot and make the switch go bad. When I replace them I put in a 20 amp rated switch with 1/4 inch terminals, and a short section of better wire to the switch. If you make better connections it stops the wires from getting hot and the switch will last a long time.

either the circulation fan that cools the magnatron is bad,or the magnatron is bad itself.

Replace the magnetron, safety fuse and diode as a set and check the door interlock switches.
That should get it working for another year or so.
Don't forget microwave mains fuses are special sand filled and semisurge type.

magnetron do get week over time even more so if you do a lot of short time food reheat, the fan normally is used to cool the magnetron wave guide and if it stops working the over temp safety will trip and stop the magnetron from working

In all likelihood the mangnetron has failed, or perhaps even the Power Supply. You need to have it serviced by a reputable service centre/man.
Ensure you get a firm "Quote" before proceeding, and remember these days the cost of repair can equal or exceed the price of a new one.

Ck and make sure the circuit breaker on the power panel on the house hasn't tripped.. If your microwave is within 6' of the kitchen sink, ck for a tripped GFCI controlling the power the microwave is plugged into. Good Luck, Ned

Make sure breaker isnt tripped. If breaker isnt tripped just for the sake of knowing plug a fan or something you know that works in the outlet. If it works, you have probably blown fuses in the microwave you'll have to take microwave apart to get to them.

The HV diode in the power supply for the magnetron is probably shorted.

Assuming that your internal cooling fan is working, I would suspect that your magnetron is failing.

You can usually find helpful exploded view diagrams and order parts by entering your full model number here.

There should also be a "mini-manual" hidden inside the unit behind the control panel or hidden on the
left side behind the grille, which is very helpful when troubleshooting, testing, and locating components.

I would check the cooling fan, then suspect the magnetron.

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