• ** 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

721.61289100 Kenmore Microwave with no heat

Pizzaguy

Member
Joined
Feb 17, 2018
Messages
1
Location
OR
Model Number
721.61289100
Brand
Sears Kenmore
Age
More than 10 years
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:

Jake

Appliance Tech - Admin
Staff member
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Aug 24, 2004
Messages
102,105
Location
McMullen Valley, Arizona
I fixed the subject line for you.:)

I'll ask Rick if he can assist you.

Jake
 

rickgburton

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