Fuse blows after about a week of working.

You would better served replacing unit. Throwing parts at it is an unnecessary step.

You have a serious short circuit, I suggest you call for a service technician

Cause 1
If too much current passes through the microwave circuitry, the line fuse will blow. If the line fuse blows, the microwave won’t start. To determine if the line fuse is at fault, use a multimeter to test it for continuity. If the fuse does not have continuity, replace it. In addition, you should investigate and resolve the problem that caused the fuse to blow. If you don’t resolve the underlying issue, the new fuse will blow too

Cause 2

Main Control Board

The main control board might be defective. However, this is rarely the case. Control boards are often misdiagnosed—check all of the more commonly defective parts. If you have determined that all of the other components are working properly,replace the main control board.

Cause 3

Thermal Fuse

The thermal fuse cuts off power to the microwave if the microwave overheats. To determine if the thermal fuse has blown, use a multimeter to test it for continuity. If the fuse does not have continuity, replace it. The thermal fuse cannot be reset—if the fuse is blown, it must be replaced.

Since its a electrical isue cal a liscenced professiona to resolve the issue . Your microwave oven isnt at fault . I belive the supplay to it has issue and would have blown anyway.

The fuse is there to protect your home in case something has gone wrong inside your microwave. Since the fuse has blown twice, you can safely assume that there is something wrong inside. It may be fixable, it may not be economic to fix it. Impossible to troubleshoot electronics without the unit and test equipment.

Check its transformer so that you will know its fuse size

Could be a lot of things but most probably a shorted high voltage diode assembly. If not that then the magaetron or capactors. Remember be careful there are high voltages even when the oven is unpluged. The capactors are usually charged and must be discharged. If you don't know what yor doing then time to get a qualfied tech.

Good luck

You blew the fuse on the control board. Unplug it, remove the cover to expose the guts, and you should see a fuse. Replace it and try again. If it blows again, then you will likely find it cheaper to get a new microwave than have the control board replaced.

A short likely in the wiring for the light or at the safety switch embedded on the side where the door closes----be careful as a 20 amp fuse takes something major to take out.
(for it to blow)

This might be best left to a qualified service person.

With the cover off, disconnect the primary of the power transformer. Now, with a good fuse try again. If the fuse blows again check the three microswitches in the latch assembly. If the fuse doesn't blow than the magnetron or diode are shorted.

9 amps is approx. correct. Does magnatron make an odd sound when running? If not, you will need to discharge cap then clean terminals with alcahol. Replace diode as well. Should run correctly.If blows again, replace magnatron. Suggest you put a 12 amp fast blow fuse in circuit and nor a 20 fuse.If you dont have a grill or an oven, use a 10 amp fuse.