• ** 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

  • Please note, some of the links on our site are affiliate links (Learn More)

721.61289100 Kenmore Microwave with no heat


Feb 17, 2018
Model Number
Title should have been "Kenmore Microwave with no heat"... sorry.

I've been a tech for years so I'm aware of precautions around HV items. I'm not, however, a microwave oven tech, more just general electronics.

This microwave died about 5 years ago and I found a "donor" almost exact model so I swapped in the donor's magnetron, diode, cap, and transformer, and it has worked just fine since then.

The other day my wife heated some water and it worked fine. A few hours later I went to heat a lunch and got zero heat.
With a digital meter, I see the cap slowly charging as you'd expect, I ran current through the diode from a 9v battery and read battery voltage one way, and about 7.4v the other way so I think it sort of "looks like" a diode. The bimetal fuse reads 0 ohms.

I have read that the magnetron filament should read some fractional part of an ohm, say between .1 and .4 - This one reads 1.6 ohms. This is a Toshiba 2M248J but I can't find what the "correct" filament resistance should be.

On power up, I read total wallplug current at just over 8 amps which says the problem is clearly in HV. So I'm looking for a confirmation that my filament reading is definitely proof the magnetron is gone before buying another one.
Last edited:
I fixed the subject line for you.:)

I'll ask Rick if he can assist you.

.....but I can't find what the "correct" filament resistance should be.
Less than one ohm. Most common is 0 ohms or closed.

6324W1A001L Magnetron

Users who are viewing this thread

Support Our Site

If you feel that you have benefited from this site, and would like to show your appreciation, please consider making a donation.