• ** 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

KEMC308KSS04 Microwave does not heat

yihe

Premium Member
Joined
May 16, 2019
Messages
2
Location
Texas
Model Number
KEMC308KSS04
Brand
KitchenAid
Age
6-10 years
Hello
My microwave has no heat but everything else is fine. The lower over is also working well.
I did test on diode, HV capacitor, magnetron and transformer. All test good. Here are test results.
1. diode:applied 9V. there is 200mA current and voltage is 6.2V. if i revert the polarity of the 9V. There is no current and output. I did order a new diode, but i still not get the heat after installing the diode.
2. capacitor: i measured, the capacitance is 1.08uF which is in the range of 1.05+/- 3%. the resistance is 10Mohms which matches the specification.
3. magnetron. the resistance between terminals are 0.8ohms. Both are open to the ground.
4. HV transform. it has 5 wires. two wires on input side and three wires on output side. The resistance between two inputs are 0.5ohms. they are connected to magnetron fuse and interlock switch. Both are open to the ground. the three wires on the output side are one white and 2 oranges. the white is connected to HV capacitor alone. one orange is connected together with diode and magnetron on the other end of the capacitor. the other orange wire is connected to magnetron. The resistance between white and GND is 80ohms. The resistance between two orange is 0.5ohms and both open to the ground.

After all these measurements. i could not isolate where the problem is. Could you shed some lights here?
many thanks
Regards
 

Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
1,809
Location
Canada
Is 120 volts getting to the primary input of the transformer when it should be heating?

If not, the thermal cutout on the magnetron tube may be open or the control not powering the microwave heating circuit. Unfortunately a new electronic control (# 8302346) is not available any longer should it be the cause.

LINK > KitchenAid KEMC308KSS04 Magnetron Thermal Cutout

Check the cutout for continuity.

Dan O.
 

yihe

Premium Member
Joined
May 16, 2019
Messages
2
Location
Texas
Thanks
I am not sure about the 120V at the primary input. How shall i test this?
but the thermal cutoff on the magnetron is continuity(~0 ohms) so i assume that it is good. .
How can we conclude the issue is from control board? will it be a problem of door switch?

Regards
 

Dan O.

Appliance Tech
Staff member
Joined
Oct 9, 2004
Messages
1,809
Location
Canada
the thermal cutoff on the magnetron is continuity(~0 ohms) so i assume that it is good.
It sounds like it's Ok.

I am not sure about the 120V at the primary input. How shall i test this?
I'm not sure how to get access to it on your model. If not easily accessed, in some cases a test light or buzzer might be able to be connected in place of the component in question and its functioning monitored remotely. But caution; Testing on a 'live' appliance can be dangerous.

will it be a problem of door switch?
The turntable and magnetron cooling fan might also be affected by a failure of the door switches. You said everything else was working besides heating. It wouldn't hurt to check them if you can, the secondary interlock switch mainly for heating functions.

I'm not certain from the parts diagram but I think this is that switch:
LINK > Monitor Switch W10211972
 
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