Philips AKG652 Microwave blowing fuses

[YossiD]

Old Philips microwave (posting from Middle East) blowing fuses.

This microwave oven is nearly 20 years old and has been very reliable. Several years ago the fuse blew and I replaced it and all was well till now.

HV capacitor tested short so I replaced it. Starting the microwave produces a loud hum (like transformer is overloaded) for a second or so, then fuse blows.

HV diode tests open in both directions, but my ohmmeter operates with 3V so I probably can't test it properly. Can an open diode cause the fuse to blow? If not, what should I check next?

Thanks

[JWWebster]

Check your mag for a shorted leg.

[Repair-man]

A bad diode will not only cause the fuse to blow, but also creates a loud hum as you described. Try a new diode.