KMBS104ESS00 KitchenAid Microwave - Overview

My microwave began suddenly making a loud harsh humming noise while cooking food. I did not let it go on long enough to know if it cooked the food or not. I did some Internet research and learned that it was likely the Magnetron. The test for this was to run the microwave for at least a minute on the lowest power setting and see if the no ... Read more ise cycled on and off. It did, so I (actually, my wife) ordered the part from partselect.com using the model number. I was successful in replacing the part, and we are back to microwave popcorn and quick defrost for a price that was less than a service call, however, it was time consuming, required a large work area, and access to 5 out of 6 sides of the unit. So proceed at your own discretion

Caution:

The first thing in every set of repair instructions was to discharge (short-circuit) the capacitor, as it may store large (as in lethal) amounts of electricity even when it is not connected to a power source. I had never done this, but found these instructions:

“Discharging your microwave's capacitor is absolutely essential in preventing injury to your microwave, your tools, and yourself. A capacitor stores a large amount of electricity even when your microwave is unplugged, and it must be discharged before beginning any repair.
A capacitor is discharged by creating a short circuit between each of the two capacitor terminals, and between each terminal and the chassis. The chassis is the metal mounting (bare metal surface) of the capacitor. Read these directions thoroughly before you proceed.
With your microwave unit unplugged, touch the blade of a well insulated screwdriver to one terminal. Gently slide the screwdriver forward until it reaches the other terminal, holding it there for a few seconds. Be aware that this often results in a loud and startling 'POP'.
Repeat this procedure in order to create a short circuit between each capacitor terminal and the chassis (bare metal mounting plate surface). This same method can be applied to a capacitor having three, and not two, terminals.”
I had not run my microwave in over a week, and then while my part was shipping, left my microwave 'unplugged' for more than two days, and my capacitor apparently discharged itself, although I did go through the above procedure carefully and completely - just in case.
Step-By-Step:
1. You must remove your microwave from the cabinets - it is impossible to repair otherwise. This is best accomplished with 2 strong people - my wife and I made it work, but wished for another guy.
a. While supporting the microwave, remove the two screws coming down through the cabinet above.
b. Lift the rear of the microwave as much as possible, then tilt the front down - there is a clip high on the left side, as well as the hinge/clips on the bottom.
c. If you do not lift it off the wall all at once, you may have to lift the rear even farther to remove it from the hinge/clips on the bottom.
Important Note: Always beware of the microwave door, if it is bent or broken and cannot retain a seal, the microwave not function as a safety feature to keep from releasing microwaves.
2. Remove the vent cover on the top/front of the microwave - be careful, it's plastic.
3. Remove the vent cover and light panel on the bottom of the microwave - this is several screws and some simple wire clips.
4. Remove the "shell" (top and sides) of the microwave - this is several more screws on the back. Make sure to remove the plate that is holding the cord in place on the top.
5. Remove the interface panel by the screws on the top (which had been hidden by the vent cover) - the wires can remain attached, just slide it aside.
6. Remove the metal cover on the right side at the rear; this will expose the Magnetron and the Capacitor. Remember to immediately test and discharge the capacitor!

7. After you discharge the capacitor, remove the other cover plate and the support bracket - in case you haven't noticed, this is a time and space consuming operation.

8. You

Unless you have a very comfortable background with electronics and electricity, I don't necessarily recommend taking apart a microwave. If you are very handy and are going to be VERY cautious to follow the rules of discharging caps and testing voltages before moving forward, then go for it. That said, I took the microwave off and apart. ... Read more Not knowing where to find the parts, I was fortunate that the installer put the instruction book for the microwave inside the front vent slot above the touchpad for reference. it details the location of every part and it tells you very clearly what each part you test should show specific to this microwave on your multimeter. Find this guide online if you don't have it. Turn on the microwave for 20 seconds with a glass of water to make sure it's not heating - that with the noise means it's eeither the magnetron, cap, or diode. Read the notes on this site for all of the basic things to look for with the magnetron, diode, and capacitor. Once comfortable with the guide, locations of those devices, and how to test, then take it down and apart. Unfortunately, I didn't do all those things in that order, and it only wasted a lot of time trying to find the parts. Once I found the parts and put all the screws and covers back for all the areas that didn't need to be accessed for the repair, testing went quickly. The diode was bad. Ordered a new one and had it in 3 days or so. That means your microwave will be apart and sitting somewhere for a little while until you get the part and have time to repair it. Putting the diode back isn't too bad. Reassemble the microwave and put it back up again. If i had to do it again, it would take me 20 to 30 minutes once the microwave was down and on a table. Also, I used some bricks with towels over them or you could use some sawhorses to keep the microwave elevated so you can plug it in and run it after installing the new component. Again, make sure you discharge the cap before touching anything again even if you didn't run it, but just plugged it in.

I turn off the income electricity by shutting down the corresponding circuit breaker. Then, I removed the control panel from the microwave which gave me access to the capacitor and adjacent diode. After that i unscrewed the defective diode and replaced it with the new one and BINGO!