My wife's beloved 1984 microwave oven died a couple weeks ago. Fuse was blown, after some digging the HV capacitor had a shorted section. It was a 0.41/0.44uF dual-section cap rated at 2600 V. There was a cook/defrost switch that connected both sections in parallel for cook mode. The thing that has me stumped is I can't find a HV rectifier anywhere in the circuit. Yes, I can see that the magnetron could act as a rectifier, so you could build an oven that runs without a rectifier. But, one issue with doing that is that the transformer secondary would have DC in it that could saturate the transformer. The CLASSIC microwave oven circuit has the transformer feeding a capacitor that then has a rectifier with the cathode grounded and the cap/anode junction connected to the magnetron cathode. This circuit approximately balances the current in the transformer. The circuit in the existing oven seems to apply the raw secondary to the capacitor AND the magnetron cathode in parallel, causing the capacitor to have a lot of 60 Hz AC current flowing in it.
Has anyone seen a microwave oven with this circuit?
Thanks for any hints,
Jon