• ** 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

    Jake

721.80012401 Kenmore Loud humming noise no heat

quatin

Member
Joined
Jun 26, 2019
Messages
1
Location
florida
Model Number
721.80012401
Brand
Sears Kenmore
Age
More than 10 years
I removed the cabinet and found the trouble shooting manual folded up in the panel. I discharged the HV capacitor, but everything seemed to measure ok. From googling, everything points to the magnetron or diode, but I can't see anything wrong. I even removed the magnetron and visually inspected for cracks in the magnet or antenna.

Things done so far:

Primary transformer coils: low ohmage
Primary transformer coil to chassis: open
2ndary coil to chassis: 90ohmish
filament coil: low ohmage
filament coil to chassis: open
Magnetron terminals: 1.5 ohm (that's as low as my MM measures)
Mangetron terminal to chassis: open
Capacitor terminals to chassis: open
Capacitor + terminal to - terminal: starts at 2Megaohms and charges to 10Megaohms
Diode: I put a 12V battery in series, but with a MM closing the loop so it's high resistance. Measured across the anode and cathode: 8.4V. Flipped polarity of battery, measured 0V
Measured across all the resistors in the filter circuit board.

Everything seemed fine to me. I'm not sure what else to check here.
 

rickgburton

Appliance Tech - Moderator
Staff member
Joined
Jul 11, 2006
Messages
34,789
Location
Murray, Utah 84107, United States
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