Microwave blows fuse in microwave mode grill function ok

I guess the main plug fuse does not blow for the same reason it does not blow and you can wreck a PC, although not certain why that is. I have a feeling from past work on a Panasonic that there is an internal fuse as well. This may have blown with the power surge.

Usually when a microwave's fuse blows, it will be dead, not partially functioning.
It may be a bad door switch or mount.
(Anybody in the home opening the door while it's cooking?)
See our help file on door switches here.

The magnetron is the likely problem, {heart of the microwave oven}

Maybe... Did you check the high voltage diode?... A shorted diode keeps the fuse blown... Ty

Fuses seldom just go bad on their own, but it's safe to replace. Before you replace the fuse, squeeze the tabs of the fuse holder clips together a bit. Sometimes they don't grip the fuse tightly enough, and this can cause heating which damages the fuse. If the fuse blows again there is a bad part in the oven that will need to be located and replaced. For a small countertop oven, it's probably more economical just to replace the oven than to repair it.

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.

Hi! the problem you have mentioned indicates that your microwave magnetron is not working. check for busted fuses.

Sounds like the fuse is blown, you will have take the outer case off to find the fuse and replace it

The micro wave part is not working in your oven. It is mainly due to to the defect in the magnetron and the related components like high voltage side fuse and high voltage diode etc. you can check the fuse and the diode with a multimeter. If they are ok replace the magnetron.

It's 20mm !!
It will have failed for a reason.
At 15amps, I'm guessing your Microwave has a grill too.
It could just be a bulb failure causing the fuse to blow.
Replace it and try again.
If the oven works but no light, that was the cause.