• ** REMEMBER! **The microwave can still shock you even unplugged!!

    ALWAYS discharge the high-voltage capacitor first if you even think your hands will come close to any HIGH VOLTAGE components.

    Jeff mentions this: Anything in the high voltage ( magnetron, capacitor, diode, wires to and from ):
    ...Use a metal ( not the shiny chrome type ) screw driver with a insulated handle to short across ( touch both at the same time ) the terminals of the high voltage capacitor to discharge it.

    From Jeff's site: http://www.applianceaid.com/component-testing.php

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Bosch Microwave HMV3053U/01 runs, but hums loudly after about 5 seconds


Premium Member
Apr 12, 2023
Model Number
1-5 years
The unit runs and heats, it just hums quite loudly. I've replaced the diode and the capacitor with no change. This leaves me with either the magnetron, or the HV transformer. The problem is that they both check perfectly fine, at least on the bench with a multimeter. Resistance and continuity passes on both components with flying colors. I'm leaning toward the magnetron, but I really don't want to buy it, just to find out it was the HV transformer all along.

Your thoughts would be most welcome, or at least a set of educated guesses to help me narrow down the odds. Many thanks!
Welp, it wasn't the magnetron. First one arrived faulty (open filament), and replacement does the same exact thing as the old one. Starts, and begins humming loudly after about three seconds.

Since I've replaced all the other HV components, it looks like it must be the HV transformer. Alas.

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